HK1215707B

HK1215707B - Piperidinone derivatives as mdm2 inhibitors for the treatment of cancer

Info

Publication number: HK1215707B
Application number: HK16103660.5A
Authority: HK
Inventors: Michael David Bartberger; Ana Gonzalez Buenrostro; Hilary Plake Beck; Xiaoqi Chen; Richard Victor Connors; Jeffery Deignan; Jason Duquette; John Eksterowicz; Benjamin Fisher; Brian Matthew Fox; Jiasheng Fu; Zice Fu; Felix Gonzalez Lopez De Turiso; Jr. Michael William Gribble; Darin James Gustin; Julie Anne Heath; Xin Huang; Xianjun JIAO; Michael Johnson; Frank Kayser
Original assignee: Amgen Inc.
Priority date: 2010-06-04
Filing date: 2016-03-30
Publication date: 2019-10-18

Description

FIELD OF THE INVENTION

The present invention relates to a pharmaceutical composition comprising the compound 2-((3R,5R,6S)-5-(3-Chlorophenyl)-6-(4-chlorophenyl)-1-((S)-1-(isopropylsulfonyl)-3-methylbutan-2-yl)-3-methyl-2-oxopiperidin-3-yl)acetic acid or a pharmaceutically acceptable salt, ester or amide thereof as defined in claim 1, together with a pharmaceutically acceptable excipient, diluent or carrier, which pharmaceutical composition is a solid dosage form, is a composition suitable for parenteral injection, or is a liquid dosage form for oral administration. The compound is an MDM2 inhibitor that is useful as therapeutic agent particularly for the treatment of cancers. The present invention further relates to the compound 2-((3R,5R,6S)-5-(3-Chlorophenyl)-6-(4-chlorophenyl)-1-((S)-1-(isopropylsulfonyl)-3-methylbutan-2-yl)-3-methyl-2-oxopiperidin-3-yl)acetic acid or a pharmaceutically acceptable salt, ester or amide thereof for use in a method of treating various types of cancers, as defined in any one of claims 5 to 13. The invention further relates to a medicament as defined in claims 14 to 16, as well as to esters, amides and prodrugs of the compound, as defined in claim 17, and a pharmaceutical composition comprising the ester, amide or prodrug, as defined in claim 18.

BACKGROUND OF THE INVENTION

p53 is a tumor suppressor and transcription factor that responds to cellular stress by activating the transcription of numerous genes involved in cell cycle arrest, apoptosis, senescence, and DNA repair. Unlike normal cells, which have infrequent cause for p53 activation, tumor cells are under constant cellular stress from various insults including hypoxia and pro-apoptotic oncogene activation. Thus, there is a strong selective advantage for inactivation of the p53 pathway in tumors, and it has been proposed that eliminating p53 function may be a prerequisite for tumor survival. In support of this notion, three groups of investigators have used mouse models to demonstrate that absence of p53 function is a continuous requirement for the maintenance of established tumors. When the investigators restored p53 function to tumors with inactivated p53, the tumors regressed.

p53 is inactivated by mutation and/or loss in 50% of solid tumors and 10% of liquid tumors. Other key members of the p53 pathway are also genetically or epigenetically altered in cancer. MDM2, an oncoprotein, inhibits p53 function, and it is activated by gene amplification at incidence rates that are reported to be as high as 10%. MDM2, in turn, is inhibited by another tumor suppressor, p14ARF. It has been suggested that alterations downstream of p53 may be responsible for at least partially inactivating the p53 pathway in p53^WT tumors (p53 wildtype). In support of this concept, some p53^WT tumors appear to exhibit reduced apoptotic capacity, although their capacity to undergo cell cycle arrest remains intact. One cancer treatment strategy involves the use of small molecules that bind MDM2 and neutralize its interaction with p53. MDM2 inhibits p53 activity by three mechanisms: 1) acting as an E3 ubiquitin ligase to promote p53 degradation; 2) binding to and blocking the p53 transcriptional activation domain; and 3) exporting p53 from the nucleus to the cytoplasm. All three of these mechanisms would be blocked by neutralizing the MDM2-p53 interaction. In particular, this therapeutic strategy could be applied to tumors that are p53^WT, and studies with small molecule MDM2 inhibitors have yielded promising reductions in tumor growth both in vitro and in vivo. Further, in patients with p53-inactivated tumors, stabilization of wildtype p53 in normal tissues by MDM2 inhibition might allow selective protection of normal tissues from mitotic poisons.

The present invention relates to compounds capable of inhibiting the interaction between p53 and MDM2 and activating p53 downstream effector genes. As such, compounds of the present invention would be useful in the treatment of cancers, bacterial infections, viral infections, ulcers and inflammation. In particular, the compounds of the present invention are useful to treat solid tumors such as: breast, colon, lung and prostate tumors; and liquid tumors such as lymphomas and leukemias. As used herein, MDM2 means a human MDM2 protein and p53 means a human p53 protein. It is noted that human MDM2 can also be referred to as HDM2 or hMDM2.

SUMMARY OF THE INVENTION

The present invention relates to a pharmaceutical composition comprising the compound 2-((3R,5R,6S)-5-(3-Chlorophenyl)-6-(4-chlorophenyl)-1-((S)-1-(isopropylsulfonyl)-3-methylbutan-2-yl)-3-methyl-2-oxopiperidin-3-yl)acetic acid or a pharmaceutically acceptable salt, ester or amide thereof as defined in claim 1, together with a pharmaceutically acceptable excipient, diluent or carrier, which pharmaceutical composition is a solid dosage form, is a composition suitable for parenteral injection, or is a liquid dosage form for oral administration. The pharmaceutical composition of the present invention is defined in claims 1, and particular embodiments of the solid dosage form are defined in claims 2 to 4.

The present invention further relates to the compound 2-((3R,5R,6S)-5-(3-Chlorophenyl)-6-(4-chlorophenyl)-1-((S)-1-(isopropylsulfonyl)-3-methylbutan-2-yl)-3-methyl-2-oxopiperidin-3-yl)acetic acid or a pharmaceutically acceptable salt, ester or amide thereof for use in a method of treating various types of cancers, as defined in any one of claims 5 to 13. The invention further relates to a medicament as defined in any one of claims 14 to 16, as well as to esters, amides and prodrugs of the compound, as defined in claim 17, and to a pharmaceutical composition comprising the ester, amide or prodrug, as defined in claim 18.

DETAILED DESCRIPTION OF THE INVENTION

Where the term "alkyl" is used, either alone or within other terms such as "haloalkyl" or "alkylamino", it embraces linear or branched radicals having the indicated number of carbon atoms. Examples of such radicals include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, pentyl, isoamyl, hexyl and the like.

The term "alkoxy" embraces linear or branched oxy-containing radicals each having alkyl portions with the indicated number of carbon atoms.Examples of such radicals include methoxy, ethoxy, propoxy, butoxy and tert-butoxy.

The term "aryl", alone or in combination, means a carbocyclic aromatic system containing one or two rings, wherein such rings may be attached together in a fused manner. The term "aryl" embraces aromatic radicals such as phenyl, naphthyl, indenyl, tetrahydronaphthyl, and indanyl. More preferred aryl is phenyl.

The term "carbonyl," whether used alone or with other terms, such as "aminocarbonyl," denotes -(C=O)-.

The term "N,N-dialkylamino" embraces a group where an amino group is independently substituted with two alkyl radicals having the indicated number of carbon atomsSuitable N,N-dialkylamino radicals may be N,N-dimethylamino and N,N-diethylamino.

The term "cycloalkyl" includes saturated carbocyclic groups. Preferred cycloalkyl groups include cyclopentyl and cyclohexyl.

The term "comprising" is meant to be open ended, including the indicated component but not excluding other elements.

The term "therapeutically effective amount" means an amount of a compound that ameliorates, attenuates or eliminates one or more symptom of a particular disease or condition, or prevents or delays the onset of one of more symptom of a particular disease or condition.

The terms "patient" and "subject" may be used interchangeably and mean animals, such as dogs, cats, cows, horses, sheep and humans. Particular patients are mammals. The term patient includes males and females.

The term "pharmaceutically acceptable" means that the referenced substance, i.e. 2-((3R,5R,6S)-5-(3-Chlorophenyl)-6-(4-chlorophenyl)-1-((S)-1-(isopropylsulfonyl)-3-methylbutan-2-yl)-3-methyl-2-oxopiperidin-3-yl)acetic acid or a salt, ester or amide thereof, or a formulation containing 2-((3R,5R,6S)-5-(3-Chlorophenyl)-6-(4-chlorophenyl)-1-((S)-1-(isopropylsulfonyl)-3-methylbutan-2-yl)-3-methyl-2-oxopiperidin-3-yl)acetic acid or a salt, ester or amide thereof, or a particular excipient, are suitable for administration to a patient.

The terms "treating", "treat" or "treatment" and the like include preventative (e.g., prophylactic) and palliative treatment.

The term "excipient" means any pharmaceutically acceptable additive, carrier, diluent, adjuvant, or other ingredient, other than the active pharmaceutical ingredient (API), which is typically included for formulation and/or administration to a patient.

The compound of the present invention or the pharmaceutically acceptable salt, ester, amide or prodrug thereof is administered to a patient in a therapeutically effective amount. The compound or the pharmaceutically acceptable salt, ester or amide thereof for use in a method of treating various types of cancer in a subject in need thereof, as defined in claim 5, or the medicament comprising the compound depicted in claim 1 for use in a method of treating cancer, can be administered alone or as part of a pharmaceutically acceptable composition or formulation. In addition, the compounds or compositions can be administered all at once, as for example, by a bolus injection, multiple times, such as by a series of tablets, or delivered substantially uniformly over a period of time, as for example, using transdermal delivery. It is also noted that the dose of the compound can be varied over time.

In addition, the compound or the pharmaceutically acceptable salt, ester, amide or prodrug thereof can be administered alone or with other pharmaceutically active compounds. The other pharmaceutically active compounds can be intended to treat the same disease or condition as the compound of the present invention or the salt, ester, amide or prodrug thereof or a different disease or condition. If the patient is to receive or is receiving multiple pharmaceutically active compounds, the compounds can be administered simultaneously, or sequentially. For example, in the case of tablets, the active compounds may be found in one tablet or in separate tablets, which can be administered at once or sequentially in any order. In addition, it should be recognized that the compositions may be different forms. For example, one or more compound may be delivered via a tablet, while another is administered via injection or orally as a syrup. All combinations, delivery methods and administration sequences are contemplated.

The term "cancer" means a physiological condition in mammals that is characterized by unregulated cell growth. General classes of cancers include carcinomas, lymphomas, sarcomas, and blastomas.

The compounds of the present invention can be used to treat cancer. The methods of treating a cancer comprise administering to a patient in need thereof a therapeutically effective amount of 2-((3R,5R,6S)-5-(3-Chlorophenyl)-6-(4-chlorophenyl)-1-((S)-1-(isopropylsulfonyl)-3-methylbutan-2-yl)-3-methyl-2-oxopiperidin-3-yl)acetic acid or a pharmaceutically acceptable salt, ester or amide thereof.

The compounds of the present invention can be used to treat tumors. The methods of treating a tumor comprise administering to a patient in need thereof a therapeutically effective amount of 2-((3R,5R,6S)-5-(3-Chlorophenyl)-6-(4-chlorophenyl)-1-((S)-1-(isopropylsulfonyl)-3-methylbutan-2-yl)-3-methyl-2-oxopiperidin-3-yl)acetic acid or a pharmaceutically acceptable salt, ester or amide thereof.

Cancers which may be treated with the present invention include, without limitation, carcinomas such as cancer of the bladder, breast, colon, rectum, kidney, liver, lung (small cell lung cancer, and non-small-cell lung cancer), esophagus, gall-bladder, ovary, pancreas, stomach, cervix, thyroid, prostate, and skin (including squamous cell carcinoma); hematopoietic tumors of lymphoid lineage (including leukemia, acute lymphocytic leukemia, chronic myelogenous leukemia, acute lymphoblastic leukemia, B-cell lymphoma, T-cell-lymphoma, Hodgkin's lymphoma, non-Hodgkin's lymphoma, hairy cell lymphoma and Burkett's lymphoma); hematopoietic tumors of myeloid lineage (including acute and chronic myelogenous leukemias, myelodysplastic syndrome and promyelocytic leukemia); tumors of mesenchymal origin (including fibrosarcoma and rhabdomyosarcoma, and other sarcomas, e.g., soft tissue and bone); tumors of the central and peripheral nervous system (including astrocytoma, neuroblastoma, glioma and schwannomas); and other tumors (including melanoma, seminoma, teratocarcinoma, osteosarcoma, xenoderoma pigmentosum, keratoctanthoma, thyroid follicular cancer and Kaposi's sarcoma). Other cancers that can be treated with a compound of the present invention include endometrial cancer, head and neck cancer, glioblastoma, malignant ascites, and hematopoietic cancers.

Particular cancers that can be treated by the compounds of the present invention include soft tissue sarcomas, bone cancers such as osteosarcoma, breast tumors, bladder cancer, Li-Fraumeni syndrome, brain tumors, rhabdomyosarcoma, adrenocortical carcinoma, colorectal cancer, non-small cell lung cancer, and acute myeleogenous leukemia (AML).

In a particular embodiment of the invention that relates to the treatment of cancers, the cancer is identified as p53wildtype (p53^WT). In another particular embodiment, the cancer is identified as p53^WT and CDKN2A mutant. For example, a sample of a patient's cancer cells may be taken and analyzed to determine the status of the cancer cells with respect to p53 and/or CDKN2A. In one aspect, a patient having a cancer that is p53^WT will be selected for treatment over patients having a cancer that is mutated with respect to p53. In another aspect, a patient having a cancer that is both p53^WT and has a mutant CDNK2A protein is selected over a patient that does not have these characteristics. The taking of a cancer cells for analyses is well known to those skilled in the art. The term "p53^WT" means a protein encoded by genomic DNA sequence no. NC_000017 version 9 (7512445..7531642)(GenBank); a protein encoded by cDNA sequence no. NM_000546 (GenBank); or a protein having the GenBank sequence no. NP_000537.3. The term "CDNK2A mutant" means a CDNK2A protein that in not wildtype. The term "CDKN2A wildtype" means a protein encoded by genomic DNA sequence no. 9:21957751-21984490 (Ensembl ID); a protein encoded by cDNA sequence no. NM_000077 (GenBank) or NM_058195 9GenBank) or; or a protein having the GenBank sequence no. NP_000068 or NP_478102.

The compounds of the present invention can also be used to treat hyperproliferative disorders such as thyroid hyperplasia (especially Grave's disease), and cysts (such as hypervascularity of ovarian stroma, characteristic of polycystic ovarian syndrome (Stein-Leventhal syndrome)).

The compounds of the present invention can also be used to treat the following diseases or conditions: asthma, chronic obstructive pulmonary disease (COPD), emphysema, psoriasis, contact dermatitis, conjunctivitis, allergic rhinitis, systemic lupus erythematosus (SLE), ulcerative colitis, Crohn's disease, multiple sclerosis, rheumatoid arthritis, inflammatory bowel disease, Alzheimer's disease, atherosclerosis and Huntington's disease.

The compounds of the present invention can also be used to treat inflammatory diseases, hypoxia, ulcers, viral infections, bacterial infections, and bacterial sepsis.

The compound 2-((3R,5R,6S)-5-(3-Chlorophenyl)-6-(4-chlorophenyl)-1-((S)-1-(isopropylsulfonyl)-3-methylbutan-2-yl)-3-methyl-2-oxopiperidin-3-yl)acetic acid or the pharmaceutically acceptable salt, ester, amide or prodrug thereof, as defined in the claims, may also be administered in combination with one or more additional pharmaceutically active compounds/agents. In a particular embodiment, the additional pharmaceutically active agent is an agent that can be used to treat a cancer. For example, an additional pharmaceutically active agent can be selected from antineoplastic agents, anti-angiogenic agents, chemotherapeutic agents and peptidal cancer therapy agents. In yet another embodiment, the antineoplastic agents are selected from antibiotic-type agents, alkylating agents, antimetabolite agents, hormonal agents, immunological agents, interferon-type agents, kinase inhibitors, miscellaneous agents and combinations thereof. It is noted that the additional pharmaceutically active compounds/agents may be a traditional small organic chemical molecules or can be macromolecules such as a proteins, antibodies, peptibodies, DNA, RNA or fragments of such macromolecules.

Examples of specific pharmaceutically active agents that can be used in the treatment of cancers and that can be used in combination with one or more compound of the present invention include: methotrexate; tamoxifen; fluorouracil; 5-fluorouracil; hydroxyurea; mercaptopurine; cisplatin; carboplatin; daunorubicin; doxorubicin; etoposide; vinblastine; vincristine; pacitaxel; thioguanine; idarubicin; dactinomycin; imatinib; gemcitabine; altretamine; asparaginase; bleomycin; capecitabine; carmustine; cladisat. aq. NaCl solution; cyclophosphamine; cytarabine; decarazine; docetaxel; idarubicin; ifosfamide; irinotecan; fludarabine; mitosmycin; mitoxane; mitoxantrone; topotecan; vinorelbine; adriamycin; mithram; imiquimod; alemtuzmab; exemestane; bevacizumab; cetuximab; azacitidine; clofarabine; decitabine; desatinib; dexrazoxane; docetaxel; epirubicin; oxaliplatin; erlotinib; raloxifene; fulvestrant; letrozole; gefitinib; gemtuzumab; trastuzumab; gefitinib; ixabepilone; lapatinib; lenalidomide; aminolevulinic acid; temozolomide; nelarabine; sorafenib; nilotinib; pegaspargase; pemetrexed; rituximab; dasatinib; thalidomide; bexarotene; temsirolimus; bortezomib; vorinostat; capecitabine; zoledronic acid; anastrozole; sunitinib; aprepitant and nelarabine, or a pharmaceutically acceptable salt thereof.

Additional pharmaceutically active agents that can be used in the treatment of cancers and that can be used in combination with one or more compound of the present invention include: vascular endothelial growth factor (VEGF) inhibitors, hepatocyte growth factor/scatter factor (HGF/SF) inhibitors, angiopoietin 1 and/or 2 inhibitors, tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) agonists, recombinant human apo2 ligand (TRAIL), insulin-like growth factor 1 receptor (IGFR-1) inhibitors, cFMS inhibitors, HER 2 inhibitors, c-met inhibitors, aurora kinase inhibitors, CDK 4 and/or 6 inhibitors, and B-raf inhibitors.

Further additional pharmaceutically active agents that can be used in the treatment of cancers and that can be used in combination with one or more compound of the present invention include antibody drug conjugates (ADCs) whereby an antibody that binds to a protein, preferably on a cancer cell, is conjugated using a linker with a chemical compound that is detrimental to the cancer cell. Examples of chemical compounds that are detrimental to a cancer cell include maytansinoids derivatives and auristatin derivatives.

Still further additional pharmaceutically active agents that can be used in the treatment of cancers and that can be used in combination with one or more compound of the present invention include: epoetin alfa; darbepoetin alfa; panitumumab; pegfilgrastim; palifermin; filgrastim; denosumab; ancestim; AMG 102; AMG 319; AMG 386; AMG 479 (Ganitumab); AMG 511, AMG 900, AMG 655 (Conatumumab); AMG 745; AMG 951; and AMG 706 (Motesanib), or a pharmaceutically acceptable salt thereof.

In another aspect, the present invention relates to the use of the compounds of the present invention in combination with one or more pharmaceutical agent that is an inhibitor of a protein in the phosphatidylinositol 3-kinase (PI3K) pathway. Combinations of compounds of the present invention along with inhibitors of proteins in the PI3K pathway have shown synergy in cancer cell growth assays, including enhanced apoptosis and cell killing. Examples of proteins in the PI3K pathway include PI3K, mTOR and PKB (also known as Akt). The PI3K protein exists in several isoforms including α, β, δ, or γ. It is contemplated that a PI3K inhibitor that can be used in combination with a compound of the present invention can be selective for one or more isoform. By selective it is meant that the compounds inhibit one or more isoform more that other isoforms. Selectivity is a concept well known to those is the art and can be measured with well known activity in vitro or cell-based assays. Preferred selectivity includes greater than 2 fold, preferably 10 fold, or more preferably 100 fold greater selectivity for one or more isoform over the other isoforms. In one aspect, the PI3K inhibitors that can be used in combination with compounds of the present invention is a PI3K α selective inhibitor. In another aspect the compound is a PI3K δ selective inhibitor.

Preferred PI3K inhibitors for use in combination with compounds of the present invention include: or , or a pharmaceutically acceptable salt thereof.

Also preferred is a compound of Formula IIa below, or a pharmaceutically acceptable salt thereof, wherein X¹ is fluorine or hydrogen; Y¹ is hydrogen or methyl; and Z¹ is hydrogen or methyl.

Compounds that inhibit both PI3K and mTOR (dual inhibitors) are known. In still another aspect, the present invention provides the use of dual PI3K and mTOR inhibitors for use in combination with a compound of the present invention.

mTOR is a protein in the PI3K pathway. It is another aspect of the present invention to use an mTOR inhibitor in combination with one or more compounds of the present invention. mTOR inhibitors that can be used in combination with compounds of the present invention include those disclosed in the following documents: PCT published application no. WO2010/132598 or PCT published application no. WO2010/096314 .

PKB (Akt) is also a protein in the PI3K pathway. It is another aspect of the present invention to use an mTOR inhibitor in combination with one or more compounds of the present invention. PKB inhibitors that can be used in combination with compounds of the present invention include those disclosed in the following documents: U.S. patent no. 7,354,944 ; U.S. patent no. 7,700,636 ; U.S. patent no. 7,919,514 ; U.S. patent no. 7,514,566 ; U.S. patent application publication no. US 2009/0270445 A1 ; U.S. patent no. 7,919,504 ; U.S. patent no. 7,897,619 ; or PCT published application no. WO 2010/083246 A1 .

The compounds of the present invention can be used in combination with CDK4 and/or 6 inhibitors. CDK 4 and/or 6 inhibitors that can be used in combination with compounds of the present invention include those disclosed in the following documents: PCT published application no. WO 2009/085185 or U.S. patent application publication no. US2011/0097305 .

The compounds of the present invention can also be used in combination with pharmaceutically active agents that treat nausea. Examples of agents that can be used to treat nausea include: dronabinol; granisetron; metoclopramide; ondansetron; and prochlorperazine; or a pharmaceutically acceptable salt thereof.

In addition, the compounds of the present invention can be used in combination with other agents that can be used to treat cancer such as acemannan; aclarubicin; aldesleukin; alitretinoin; amifostine; amrubicin; amsacrine; anagrelide; arglabin; arsenic trioxide; BAM 002 (Novelos); bicalutamide; broxuridine; celmoleukin; cetrorelix; cladribine; clotrimazole; DA 3030 (Dong-A); daclizumab; denileukin diftitox; deslorelin; dilazep; docosanol; doxercalciferol; doxifluridine; bromocriptine; cytarabine; HIT diclofenac; interferon alfa; tretinoin; edelfosine; edrecolomab; eflornithine; emitefur; epirubicin; epoetin beta; etoposide phosphate; exisulind; fadrozole; finasteride; fludarabine phosphate; formestane; fotemustine; gallium nitrate; gemtuzumab zogamicin; gimeracil/oteracil/tegafur combination; glycopine; goserelin; heptaplatin; human chorionic gonadotropin; human fetal alpha fetoprotein; ibandronic acid; interferon alfa; interferon alfa natural; interferon alfa-2; interferon alfa-2a; interferon alfa-2b; interferon alfa-Nl; interferon alfa-n3; interferon alfacon-1; interferon alpha natural; interferon beta; interferon beta-1a; interferon beta-lb; interferon gamma natural; interferon gamma-la; interferon gamma-lb; interleukin-1 beta; iobenguane; irsogladine; lanreotide; LC 9018 (Yakult); leflunomide; lenograstim; lentinan sulfate; letrozole; leukocyte alpha interferon; leuprorelin; levamisole + fluorouracil; liarozole; lobaplatin; lonidamine; lovastatin; masoprocol; melarsoprol; metoclopramide; mifepristone; miltefosine; mirimostim; mismatched double stranded RNA; mitoguazone; mitolactol; mitoxantrone; molgramostim; nafarelin; naloxone + pentazocine; nartograstim; nedaplatin; nilutamide; noscapine; novel erythropoiesis stimulating protein; NSC 631570 octreotide; oprelvekin; osaterone; paclitaxel; pamidronic acid; peginterferon alfa-2b; pentosan polysulfate sodium; pentostatin; picibanil; pirarubicin; rabbit antithymocyte polyclonal antibody; polyethylene glycol interferon alfa-2a; porfimer sodium; raltitrexed; rasburicase; rhenium Re 186 etidronate; RII retinamide; romurtide; samarium (153 Sm) lexidronam; sargramostim; sizofiran; sobuzoxane; sonermin; strontium-89 chloride; suramin; tasonermin; tazarotene; tegafur; temoporfin; teniposide; tetrachlorodecaoxide; thymalfasin; thyrotropin alfa; toremifene; tositumomab-iodine 131; treosulfan; tretinoin; trilostane; trimetrexate; triptorelin; tumor necrosis factor alpha natural; ubenimex; bladder cancer vaccine; Maruyama vaccine; melanoma lysate vaccine; valrubicin; verteporfin; virulizin; zinostatin stimalamer; abarelix; AE 941 (Aeterna); ambamustine; antisense oligonucleotide; bcl-2 (Genta); APC 8015 (Dendreon); dexaminoglutethimide; diaziquone; EL 532 (Elan); EM 800 (Endorecherche); eniluracil; etanidazole; fenretinide; filgrastim SD01 (Amgen); galocitabine; gastrin 17 immunogen; HLA-B7 gene therapy (Vical); granulocyte macrophage colony stimulating factor; histamine dihydrochloride; ibritumomab tiuxetan; ilomastat; IM 862 (Cytran); interleukin-2; iproxifene; LDI 200 (Milkhaus); leridistim; lintuzumab; CA 125 monoclonal antibody(MAb) (Biomira); cancer MAb (Japan Pharmaceutical Development); HER-2 and Fc MAb (Medarex); idiotypic 105AD7 MAb (CRC Technology); idiotypic CEA MAb (Trilex); LYM-1-iodine 131 MAb (Techniclone); polymorphic epithelial mucin-yttrium 90 MAb (Antisoma); marimastat; menogaril; mitumomab; motexafin gadolinium; MX 6 (Galderma); nolatrexed; P 30 protein; pegvisomant; porfiromycin; prinomastat; RL 0903 (Shire); rubitecan; satraplatin; sodium phenylacetate; sparfosic acid; SRL 172 (SR Pharma); SU 5416 (Pfizer); TA 077 (Tanabe); tetrathiomolybdate; thaliblastine; thrombopoietin; tin ethyl etiopurpurin; tirapazamine; cancer vaccine (Biomira); melanoma vaccine (New York University); melanoma vaccine (Sloan Kettering Institute); melanoma oncolysate vaccine (New York Medical College); viral melanoma cell lysates vaccine (Royal Newcastle Hospital); or valspodar. It is noted that the agents recited above may also be administered as pharmaceutically acceptable salts when appropriate.

The compounds of the present invention may also be used in combination with radiation therapy, hormone therapy, surgery and immunotherapy, which therapies are well known to those skilled in the art.

Since one aspect of the present invention contemplates the treatment of the disease/conditions with a combination of pharmaceutically active compounds that may be administered separately, the invention further relates to combining separate pharmaceutical compositions in kit form. The kit comprises two separate pharmaceutical compositions: a compound of the present invention, and a second pharmaceutical compound. The kit comprises a container for containing the separate compositions such as a divided bottle or a divided foil packet. Additional examples of containers include syringes, boxes and bags. Typically, the kit comprises directions for the use of the separate components. The kit form is particularly advantageous when the separate components are preferably administered in different dosage forms (e.g., oral and parenteral), are administered at different dosage intervals, or when titration of the individual components of the combination is desired by the prescribing physician or veterinarian.

An example of such a kit is a so-called blister pack. Blister packs are well known in the packaging industry and are being widely used for the packaging of pharmaceutical unit dosage forms (tablets, capsules, and the like). Blister packs generally consist of a sheet of relatively stiff material covered with a foil of a preferably transparent plastic material. During the packaging process recesses are formed in the plastic foil. The recesses have the size and shape of the tablets or capsules to be packed. Next, the tablets or capsules are placed in the recesses and the sheet of relatively stiff material is sealed against the plastic foil at the face of the foil which is opposite from the direction in which the recesses were formed. As a result, the tablets or capsules are sealed in the recesses between the plastic foil and the sheet. Preferably the strength of the sheet is such that the tablets or capsules can be removed from the blister pack by manually applying pressure on the recesses whereby an opening is formed in the sheet at the place of the recess. The tablet or capsule can then be removed via said opening.

It may be desirable to provide a memory aid on the kit, e.g., in the form of numbers next to the tablets or capsules whereby the numbers correspond with the days of the regimen which the tablets or capsules so specified should be ingested. Another example of such a memory aid is a calendar printed on the card, e.g., as follows "First Week, Monday, Tuesday, ... etc ... Second Week, Monday, Tuesday, ... " etc. Other variations of memory aids will be readily apparent. A "daily dose" can be a single tablet or capsule or several pills or capsules to be taken on a given day. Also, a daily dose of a compound of the present invention can consist of one tablet or capsule, while a daily dose of the second compound can consist of several tablets or capsules and vice versa. The memory aid should reflect this and aid in correct administration of the active agents.

In another specific embodiment of the invention, a dispenser designed to dispense the daily doses one at a time in the order of their intended use is provided. Preferably, the dispenser is equipped with a memory-aid, so as to further facilitate compliance with the regimen. An example of such a memory-aid is a mechanical counter which indicates the number of daily doses that has been dispensed. Another example of such a memory-aid is a battery-powered micro-chip memory coupled with a liquid crystal readout, or audible reminder signal which, for example, reads out the date that the last daily dose has been taken and/or reminds one when the next dose is to be taken.

The compounds of the present invention and other pharmaceutically active compounds, if desired, can be administered to a patient either orally, rectally, parenterally, (for example, intravenously, intramuscularly, or subcutaneously) intracisternally, intravaginally, intraperitoneally, intravesically, locally (for example, powders, ointments or drops), or as a buccal or nasal spray. All methods that are used by those skilled in the art to administer a pharmaceutically active agent are contemplated. A specific aspect is the pharmaceutical composition as defined in claims 1 to 4, which is a solid dosage form, is a composition suitable for parenteral injection, or is a liquid dosage form for oral administration. The medicament for use in the treatment of cancer as defined in claims 14 to 16 or the compound for use in the treatment of certain cancers as defined in claims 5 to 13, as well as the ester, amide or prodrug as defined in claim 17 and comprised in the pharmaceutical composition as defined in claim 18 is not limited with respect to the administration form.

Compositions suitable for parenteral injection may comprise physiologically acceptable sterile aqueous or nonaqueous solutions, dispersions, suspensions, or emulsions, and sterile powders for reconstitution into sterile injectable solutions or dispersions. Examples of suitable aqueous and nonaqueous carriers, diluents, solvents, or vehicles include water, ethanol, polyols (propylene glycol, polyethylene glycol, glycerol, and the like), suitable mixtures thereof, vegetable oils (such as olive oil) and injectable organic esters such as ethyl oleate. Proper fluidity can be maintained, for example, by the use of a coating such as lecithin, by the maintenance of the required particle size in the case of dispersions, and by the use of surfactants.

These compositions may also contain adjuvants such as preserving, wetting, emulsifying, and dispersing agents. Microorganism contamination can be prevented by adding various antibacterial and antifungal agents, for example, parabens, chlorobutanol, phenol, sorbic acid, and the like. It may also be desirable to include isotonic agents, for example, sugars, sodium chloride, and the like. Prolonged absorption of injectable pharmaceutical compositions can be brought about by the use of agents delaying absorption, for example, aluminum monostearate and gelatin.

Solid dosage forms for oral administration include capsules, tablets, powders, and granules. In such solid dosage forms, the active compound is admixed with at least one inert customary excipient (or carrier) such as sodium citrate or dicalcium phosphate or (a) fillers or extenders, as for example, starches, lactose, sucrose, mannitol, and silicic acid; (b) binders, as for example, carboxymethylcellulose, alginates, gelatin, polyvinylpyrrolidone, sucrose, and acacia; (c) humectants, as for example, glycerol; (d) disintegrating agents, as for example, agar-agar, calcium carbonate, potato or tapioca starch, alginic acid, certain complex silicates, and sodium carbonate; (a) solution retarders, as for example, paraffin; (f) absorption accelerators, as for example, quaternary ammonium compounds; (g) wetting agents, as for example, cetyl alcohol and glycerol monostearate; (h) adsorbents, as for example, kaolin and bentonite; and (i) lubricants, as for example, talc, calcium stearate, magnesium stearate, solid polyethylene glycols, sodium lauryl sulfate, or mixtures thereof. In the case of capsules, and tablets, the dosage forms may also comprise buffering agents.

Solid compositions of a similar type may also be used as fillers in soft and hard filled gelatin capsules using such excipients as lactose or milk sugar, as well as high molecular weight polyethylene glycols, and the like.

Solid dosage forms such as tablets, dragees, capsules, pills, and granules can be prepared with coatings and shells, such as enteric coatings and others well known in the art. They may also contain opacifying agents, and can also be of such composition that they release the active compound or compounds in a certain part of the intestinal tract in a delayed manner. Examples of embedding compositions that can be used are polymeric substances and waxes. The active compounds can also be in micro-encapsulated form, if appropriate, with one or more of the above-mentioned excipients.

Liquid dosage forms for oral administration include pharmaceutically acceptable emulsions, solutions, suspensions, syrups, and elixirs. In addition to the active compounds, the liquid dosage form may contain inert diluents commonly used in the art, such as water or other solvents, solubilizing agents and emulsifiers, as for example, ethyl alcohol, isopropyl alcohol, ethyl carbonate, ethyl acetate, benzyl alcohol, benzyl benzoate, propylene glycol, 1,3-butylene glycol, dimethylformamide, oils, in particular, cottonseed oil, groundnut oil, corn germ oil, olive oil, castor oil, and sesame seed oil, glycerol, tetrahydrofurfuryl alcohol, polyethylene glycols and fatty acid esters of sorbitan, or mixtures of these substances, and the like.

Besides such inert diluents, the composition can also include adjuvants, such as wetting agents, emulsifying and suspending agents, sweetening, flavoring, and perfuming agents. Suspensions, in addition to the active compound, may contain suspending agents, as for example, ethoxylated isostearyl alcohols, polyoxyethylene sorbitol and sorbitan esters, microcrystalline cellulose, aluminum metahydroxide, bentonite, agar-agar, and tragacanth, or mixtures of these substances, and the like.

Compositions for rectal administration are preferable suppositories, which can be prepared by mixing the compounds of the present invention with suitable non-irritating excipients or carriers such as cocoa butter, polyethylene glycol or a suppository wax, which are solid at ordinary room temperature, but liquid at body temperature, and therefore, melt in the rectum or vaginal cavity and release the active component.

Dosage forms for topical administration of a compound of the present invention include ointments, powders, sprays and inhalants. The active compound or fit compounds are admixed under sterile condition with a physiologically acceptable carrier, and any preservatives, buffers, or propellants that may be required. Opthalmic formulations, eye ointments, powders, and solutions are also contemplated as being within the scope of this invention.

The compounds of the present invention can be administered to a patient at dosage levels in the range of about 0.1 to about 3,000 mg per day. For a normal adult human having a body weight of about 70 kg, a dosage in the range of about 0.01 to about 100 mg per kilogram body weight is typically sufficient. The specific dosage and dosage range that can be used depends on a number of factors, including the requirements of the patient, the severity of the condition or disease being treated, and the pharmacological activity of the compound being administered. The determination of dosage ranges and optimal dosages for a particular patient is within the ordinary skill in the art.

The compounds of the present invention can be administered as pharmaceutically acceptable salts, esters, amides or prodrugs. The term "salts" refers to inorganic and organic salts of compounds of the present invention. The salts can be prepared in situ during the final isolation and purification of a compound, or by separately reacting a purified compound in its free base or acid form with a suitable organic or inorganic base or acid and isolating the salt thus formed. Representative salts include the hydrobromide, hydrochloride, sulfate, bisulfate, nitrate, acetate, oxalate, palmitiate, stearate, laurate, borate, benzoate, lactate, phosphate, tosylate, citrate, maleate, fumarate, succinate, tartrate, naphthylate, mesylate, glucoheptonate, lactobionate, and laurylsulphonate salts, and the like. The salts may include cations based on the alkali and alkaline earth metals, such as sodium, lithium, potassium, calcium, magnesium, and the like, as well as non-toxic ammonium, quaternary ammonium, and amine cations including, but not limited to, ammonium, tetramethylammonium, tetraethylammonium, methylamine, dimethylamine, trimethylamine, triethylamine, ethylamine, and the like. See, for example, S. M. Berge, et al., "Pharmaceutical Salts," J Pharm Sci, 66: 1-19 (1977).

The pharmaceutically acceptable esters of the compounds of the present invention include C₁-C₈ alkyl esters. Acceptable esters also include C₅-C₇ cycloalkyl esters, as well as arylalkyl esters such as benzyl. C₁-C₄ alkyl esters are commonly used. Esters of compounds of the present invention may be prepared according to methods that are well known in the art.

The pharmaceutically acceptable amides of the compounds of the present invention include amides derived from ammonia, primary C₁-C₈ alkyl amines, and secondary C₁-C₈ dialkyl amines. In the case of secondary amines, the amine may also be in the form of a 5 or 6 membered heterocycloalkyl group containing at least one nitrogen atom. Amides derived from ammonia, C₁-C₃ primary alkyl amines and C₁-C₂ dialkyl secondary amines are commonly used. Amides of the compounds of the present invention may be prepared according to methods well known to those skilled in the art.

The term "prodrug" means compounds that are transformed in vivo to yield a compound of the present invention. The transformation may occur by various mechanisms, such as through hydrolysis in blood. A discussion of the use of prodrugs is provided by T. Higuchi and W. Stella, "Prodrugs as Novel Delivery Systems," Vol. 14 of the A.C.S. Symposium Series, and in Bioreversible Carriers in Drug Design, ed. Edward B. Roche, American Pharmaceutical Association and Pergamon Press, 1987.

The compound of the invention contains a carboxylic acid functional group,and the prodrug is selected from an ester formed by the replacement of the hydrogen atom of the acid group by a group selected from (C₂-C₁₂)alkanoyloxymethyl, 1-(alkanoyloxy)ethyl having from 4 to 9 carbon atoms, 1-methyl-1-(alkanoyloxy)ethyl having from 5 to 10 carbon atoms, alkoxycarbonyloxymethyl having from 3 to 6 carbon atoms, 1-(alkoxycarbonyloxy)ethyl having from 4 to 7 carbon atoms, 1-methyl-1-(alkoxycarbonyloxy)ethyl having from 5 to 8 carbon atoms, N-(alkoxycarbonyl)aminomethyl having from 3 to 9 carbon atoms, 1-(N-(alkoxycarbonyl)aminomethyl having from 4 to 10 carbon atoms, 3-phthalidyl, 4-crotonolactonyl, gamma-butyrolacton-4-yl, di-N,N-(C₁-C₂)alkylamino(C₂-C₃)alkyl (such as β-dimethylaminoethyl), carbamoyl-(C₁-C₂)alkyl, N,N-di(C₁-C₂)alkylcarbamoyl-(C₁-C₂)alkyl and piperidino-, pyrrolidino- or morpholino(C₂-₃)alkyl.

The compounds of the present invention may exist in unsolvated as well as solvated forms with pharmaceutically acceptable solvents such as water (hydrate), ethanol, and the like. The present invention contemplates and encompasses both the solvated and unsolvated forms.

It is also intended that the present invention encompass compounds that are synthesized in vitro using laboratory techniques, such as those well known to synthetic chemists; or synthesized using in vivo techniques, such as through metabolism, fermentation, digestion, and the like. It is also contemplated that the compounds of the present invention may be synthesized using a combination of in vitro and in vivo techniques.

The present invention also includes isotopically-labelled compounds, which are identical to those recited herein, but for the fact that one or more atoms are replaced by an atom having an atomic mass or mass number different from the atomic mass or mass number usually found in nature. Examples of isotopes that can be incorporated into compounds of the invention include isotopes of hydrogen, carbon, nitrogen, oxygen, phosphorous, fluorine and chlorine, such as ²H, ³H, ¹³C, ¹⁴C, ¹⁵N, ¹⁶O, ¹⁷O, ¹⁸O, ³¹P, ³²P, ³⁵S, ¹⁸F, and ³⁶Cl. In one aspect, the present invention relates to compounds wherein one or more hydrogen atom is replaced with deuterium (²H) atoms.

Compounds of the present invention that contain the aforementioned isotopes and/or other isotopes of other atoms are within the scope of this invention. Certain isotopically-labelled compounds of the present invention, for example those into which radioactive isotopes such as ³H and ¹⁴C are incorporated, are useful in drug and/or substrate tissue distribution assays. Tritiated, i.e., ³H, and carbon-14, i.e., ¹⁴C, isotopes are particularly preferred for their ease of preparation and detection. Further, substitution with heavier isotopes such as deuterium, i.e., ²H, can afford certain therapeutic advantages resulting from greater metabolic stability, for example increased in vivo half-life or reduced dosage requirements and, hence, may be preferred in some circumstances. Isotopically labelled compounds of this invention can generally be prepared by substituting a readily available isotopically labelled reagent for a non-isotopically labelled reagent.

The compounds of the present invention may exist in various solid states including crystalline states and as an amorphous state. The different crystalline states, also called polymorphs, and the amorphous states of the present compounds are contemplated as part of this invention.

In synthesizing compounds of the present invention, it may be desirable to use certain leaving groups. The term "leaving groups" ("LG") generally refer to groups that are displaceable by a nucleophile. Such leaving groups are known in the art. Examples of leaving groups include, but are not limited to, halides (e.g., I, Br, F, Cl), sulfonates (e.g., mesylate, tosylate), sulfides (e.g., SCH₃), N-hydroxsuccinimide, N-hydroxybenzotriazole, and the like. Examples of nucleophiles include, but are not limited to, amines, thiols, alcohols, Grignard reagents, anionic species (e.g., alkoxides, amides, carbanions) and the like.

The examples presented below illustrate specific embodiments of the present invention. These examples are meant to be representative and are not intended to limit the scope of the claims in any manner. Unless otherwise noted, when a percent is used herein with respect to a solid, the percent is by weight with respect to the referenced solid composition. When a percent is used herein with respect to a liquid, the percent is by volume with respect to the referenced solution.

¹H-NMR spectra were typically acquired on a Bruker Avance III 500 spectrometer system (Bruker, Bilerica, MA) operating at a ¹H frequency of 500.13 MHz, equipped with a Bruker 5 mm PABBI probe with a z-axis gradient; or on a Bruker Avance II 400 spectrometer operating at a ¹H frequency of 400.23 MHz, equipped with a Bruker 5 mm PABBO probe with a z-axis gradient. Samples were typically dissolved in 500 µL of either DMSO-d₆ or CD₃OD for NMR analysis. ¹H chemical shifts are referenced to the residual solvent signals from DMSO-d₆ at δ 2.50 and CD₃OD at δ 3.30.

Significant peaks are tabulated and typically include: number of protons, multiplicity (s, singlet; d, doublet; dd, doublet of doublets; t, triplet; q, quartet; m, multiplet; br s, broad singlet) and coupling constant(s) in Hertz.

Electron Ionization (EI) mass spectra were typically recorded on an Agilent Technologies 6140 Quadrupole LC/MS mass spectrometer. Mass spectrometry results are reported as the ratio of mass over charge, sometimes followed by the relative abundance of each ion (in parentheses). Starting materials in the Examples below are typically either available from commercial sources such as Sigma-Aldrich, St. Louis, MO, or via literature procedures. The following abbreviations may be used herein:

∼: about
+ve or pos. ion: positive ion
Δ: heat
Ac: acetyl
Ac2O: acetic anhydride
aq: aqueous
AcOH: acetic acid
Bn: benzyl
Boc: tert-butyloxycarbonyl
BSA: bovine serum albumin
Bu: butyl
Bz: benzoyl
Calcd or Calc'd: calculated
Conc.: concentrated
CSA: camphor-10-sulfonic acid
d: day(s)
DBU: 1,8-diazabicyclo[5.4.0]undec-7-ene
DCE: dichloroethane
DCM: dichloromethane
DEA: diethylamine
Dess-Martin periodinane; Dess-Martin reagent: 1,1,1-triacetoxy-1,1-dihydro-1,2-benziodoxol-3-(1H)-one
DIEA or DIPEA: diisopropylethylamine
DMAP: 4-dimethylaminopyridine
DME: 1,2-dimethoxyethane
DMF: N,N-dimethylformamide
DMSO: dimethyl sulfoxide
dr: diastereomeric ratio
DTT: dithiothreitol
DVB: divinylbenzene
EDC: N-Ethyl-N' -(3-dimethylaminopropyl)carbodiimide
eq: equivalent
ESI or ES: electrospray ionization
Et: ethyl
Et2O: diethyl ether
Et3N: triethylamine
EtOAc: ethyl acetate
EtOH: ethyl alcohol
g: gram(s)
h: hour(s)
HATU: O-(7-azabenzotriazol-1-yl)-N,N,N' ,N' -tetramethyluronium hexafluorophosphate
HBTU: O-benzotriazole-N,N,N',N'-tetramethyl-uronium-hexafluorophosphate
Hex: hexanes
HMPA: hexamethylphosphoramide
HOAt: 1 -hydroxy-7-azabenzotriazole
HOBt: hydroxybenzotriazole
HPLC: high pressure liquid chromatography
IPA or iPrOH: isopropyl alcohol
Jones reagent: solution of chromium(IV)oxide and sulfuric acid in water
KHMDS: potassium hexamethyldisilazide
KOAc: potassium acetate
LCMS, LC-MS or LC/MS: liquid chromatography mass spectrometry
LDA: lithium diisopropylamide
LHMDS or LiHMDS: lithium hexamethyldisilazide
L-Selectride®: lithium tri-sec-butylborohydride (Sigma-Aldrich, St. Louis)
M: molar (mol L-1)
m/z: mass divided by charge
mCPBA: m-chloroperoxybenzoic acid
Me: methyl
MeCN: acetonitrile
MeI: iodomethane
MeOH: methyl alcohol
mg: milligram(s)
min: minute(s)
mL: milliliter(s)
M: mole(s)
MS: mass spectrometry
MsCl: methanesulfonyl chloride
MTBE or MtBE: methyl tert-butyl ether
m/z: mass-to-charge ratio
NaHMDS: sodium hexamethyldisilazide
NaOtBu: sodium tert-butoxide
NBS: N-bromosuccinimide
nBuLi: n-butyl lithium
NMO: N-methylmorpholine-N-oxide
NMP: 1-methyl-2-pyrrolidinone
NMR: nuclear magnetic resonance
N-Selectride®: sodium tri-sec-butylborohydride (Sigma-Aldrich, St. Louis)
PBS: phosphate buffered saline
PMB: paramethoxybenzyl
Pr: propyl
ppm: parts per million
rac: racemic
RP-HPLC or RPHPLC: reversed phase high pressure liquid chromatography
RT or rt: room temperature
sat. or sat'd or satd: saturated
SFC: supercritical fluid chromatography
TBAF: tetrabutylammonium fluoride
TBDMS: tert-butyldimethylsilyl
TBDMS-Cl: tert-butyldimethylsilyl chloride
TBDPS: tert-butyldiphenylsilyl
TEMPO: (2,2,6,6-tetramethylpiperidin-1-yl)oxidanyl
tert or t: tertiary
TFA: triflouroacetic acid
THF: tetrahydrofuran
TIPS: triisopropylsilyl
TLC: thin layer chromatography
TMS: trimethylsilyl or trimethylsilane
TPAP: tetrapropylammonium perruthenate
tR: retention time
tBuOH: tert-butyl alcohol
v/v: volume per volume

EXAMPLES

In the following, Reference Examples and an Example how the compounds of the invention can be prepared will be given. Reference Examples are not encompassed by the scope of the present invention.

REFERENCE EXAMPLE 1

2-((3R,5R,6S)-1-((S)-1-tert-butoxy-1-oxobutan-2-yl)-5-(3-chlorophenyl)-6-(4-chlorophenyl)-2-oxopiperidin-3-yl)acetic acid Step A. 2-(3-Chlorophenyl)-1-(4-chlorophenyl)ethanone

To a solution of 2-(3-chlorophenyl) acetic acid (10g, 58.6 mmol) in THF (58ml) was added 117 mL of a 1M solution of sodium bis-(trimethylsilyl) amide in THF slowly over 1 h at -78 °C. After being stirred at -78 °C for 40 min, a solution of methyl 4-chlorobenzoate (10g, 58.6mmol) in THF (35ml) was added over a period of 10 min. The reaction was stirred at -78 °C for 3 h, then allowed to warm to 25 °C, and stirred an additional 2 h until completion. The reaction was quenched with saturated aqueous NH₄Cl solution and most of the THF was removed under reduced pressure. The residue was extracted with ethyl acetate (2 × 100ml). The combined organic layers were washed with sat. NaCl solution, dried over Na₂SO₄, filtered and the filtrate was concentrated. The product was recrystallized from ether/pentane to provide the title compound as a white solid.

Step B. Methyl 4-(3-chlorophenyl)-5-(4-chlorophenyl)-5-oxopentanoate

To a solution of 52.1g (197 mmol) of 2-(3-chlorophenyl)-1-(4-chlorophenyl)ethanone (Reference Example 1, Step A) and methyl acrylate (19.5 ml, 216 mmol) in 360 mL of THF was added 20mL of a 1M solution of potassium tert-butoxide in THF slowly at 0 °C over a period of 20 min (reaction solution temp kept < 10 °C). The reaction was allowed to warm to ambient temperature. After being stirred at rt for 1h, the reaction was concentrated under reduced pressure, diluted with water and extracted with ethyl acetate. The combined organic layers were washed with sat. NaCl solution, dried over Na₂SO₄, filtered and the filtrate was concentrated. Purification of the residue by flash chromatography on silica gel (eluent: 15% EtOAc/hexanes) provided the title compound as a colorless liquid. R is CH₃.

Step C. (4S,5S)-Methyl 4-(3-chlorophenyl)-5-(4-chlorophenyl)-5-hydroxy pentanoate and (4R,5R)-Methyl 4-(3-chlorophenyl)-5-(4-chlorophenyl)-5-hydroxy pentanoate

To a solution of 75.1 g (213 mmol) of methyl 4-(3-chlorophenyl)-5-(4-chlorophenyl)-5-oxopentanoate (Reference Example 1, Step B) in MeOH (0.71 L, c = 0.3 M) at 0 °C was added sodium borohydride (8058 mg, 213 mmol) in several small portions. After being stirred at 0 °C for 30 min, the reaction mixture was quenched with ice-cold H₂O, concentrated under reduced pressure, and extracted with EtOAc. The combined organic layers were washed (sat. aq. NaCl solution), dried over Na₂SO₄, filtered and the filtrate was concentrated. Purification of the residue by flash chromatography on silica gel (eluent: 20 to 30% EtOAc/hexanes, gradient elution) provided a racemic mixture of the title compounds as a colorless liquid.

Step D. (4S,5R)-Methyl 5-azido-4-(3-chlorophenyl)-5-(4-chlorophenyl) pentanoate and (4R,5S)-Methyl 5-azido-4-(3-chlorophenyl)-5-(4-chlorophenyl)pentanoate

To a solution of 63.1g (179 mmol) of (4S,5S)-methyl 4-(3-chlorophenyl)-5-(4-chlorophenyl)-5-hydroxy pentanoate and (4R,5R)-methyl 4-(3-chlorophenyl)-5-(4-chlorophenyl)-5-hydroxy pentanoate (Reference Example 1, Step C) and triethylamine (49.8 ml, 357 mmol) in DCM (600 mL, 0.3 M) was added methanesulfonyl chloride (18 ml, 232 mmol) at 0 °C dropwise over a period of 10 min. The reaction was stirred at 0 °C for 40 min and monitored by TLC for completion. Then the reaction was quenched with ice-cold water, extracted (3 × DCM), and washed with sat aq. NaCl solution. The combined organic layers were dried (Na₂SO₄), and concentrated under the reduced pressure.

The crude mesylate synthesized above was dissolved in DMF (350 mL, 0.5 M) and sodium azide (58 g, 893 mmol) was added in several portions. The mixture was heated to 100 °C and after being stirred at 100 °C for 30 min, the reaction mixturewas cooled to room temperature, diluted with water and extracted with EtOAc. The combined organic layers were washed (sat. aq. NaCl solution), dried over Na₂SO₄, filtered and the filtrate was concentrated. Purification of the residue by flash chromatography on silica gel (eluent: 5 to 20% EtOAc/hexanes, gradient elution) provided the title compound as a colorless liquid.

Step E. (5R,6S)-5-(3-Chlorophenyl)-6-(4-chlorophenyl)piperidin-2-one

To a solution of 45.9 g (121 mmol) of methyl 5-azido-4-(3-chlorophenyl)-5-(4-chlorophenyl) pentanoate (Reference Example 1, Step D) in THF/H₂O (4:1, 375 mL) was added 152 mL of a 1M solution of trimethylphosphine in THF (152 mmol). After being stirred for 1 h at 25 °C, most of the THF was removed under reduced pressure. The residue was basified (ice-cold 2 M LiOH) and the product was extracted with methylene chloride. The combined organic layers were washed with sat. NaCl solution, dried over Na₂SO₄, filtered and the filtrate was concentrated under reduced pressure to provide a white solid.

This solid was dissolved in MeOH/saturated aq. NaHCO₃ (4:1, 2.4 L, c = 0.05 M) and the reaction was heated to reflux for 3 h. Excess organic solvent was removed under reduced pressure, the residue was diluted with water and extracted (2 × 10% MeOH/DCM). The combined organic layers were washed with sat. NaCl solution, dried over Na₂SO₄, filtered and the filtrate was concentrated under reduced pressure to provide trans - 5-(3-chlorophenyl)-6-(4-chlorophenyl)piperidin-2-one as a mixture of stereoisomers. Individual stereoisomers were separated by chiral HPLC (flowrate: 18 ml/min on a Chiralcel® OD-H 20 mm I.D. × 250 mm, 5 mic column (Daicel Inc., Fort Lee, NJ), using 40% isopropyl alcohol/hexane as the eluent) to to give the title compound (t _R = 8.2 min) as a white solid. [α]_D = + 158 (T = 23.4 °C, c = 1.12, MeOH); ¹H NMR (400 MHz, CHLOROFORM-d) δ ppm 7.21 (2 H, d, J = 8.2 Hz), 7.09-7.19 (3 H, m), 7.04-7.01 (1 H, m), 6.97 (2 H, d, J = 8.2 Hz), 6.80-6.77 (1 H, m), 5.83 (1 H, s, br), 4.51 (1 H, d, J = 9.8 Hz), 2.94-2.77 (1 H, m), 2.74-2.60 (2 H, m), 2.34-2.20 (1 H, m), 2.17-2.08 (1 H, m); MS (ESI) 320.0 [M + H]⁺.

Also obtained by the above method was the enantiomer of the title compound, (5S,6R)-5-(3-chlorophenyl)-6-(4-chlorophenyl)piperidin-2-one: t _R = 12.4 min; [α]_D = -156 (T = 23.4 °C, c = 1.13, MeOH).

Step F. tert-butyl (2S)-2-((2S,3R)-3-(3-chlorophenyl)-2-(4-chlorophenyl)-6-oxo-1-piperidinyl)butanoate and tert-butyl (2R)-2-((2S,3R)-3-(3-chlorophenyl)-2-(4-chlorophenyl)-6-oxo-1-piperidinyl)butanoate

To a solution of 13.5 g (42.2 mmol) of (5R,6S)-5,6-bis(4-chlorophenyl)piperidin-2-one (Reference Exampe 1, Step E) in 140 mL of DMF was added 4.22 g (105 mmol) of a dispersion of 60% sodium hydride in mineral oil at 0 °C. After being stirred for 20 min, tert-butyl 2-bromobutanoate (28.2 g, 126 mmol) was added at 0 °C and the resulting solution was stirred at 25 °C for 1.5 h until completion of the reaction. Then sat. aq. NH₄Cl solution was added and the mixture was extracted with ethylacetate. The combined organic layers were washed with water and sat. NaCl solution, dried over Na₂SO₄, filtered and the filtrate was concentrated under reduced pressure. Purification of the residue by flash chromatography on silica gel (eluent: 20 to 50% EtOAc/hexanes, gradient elution) provided tert-butyl (2S)-2-((2S,3R)-3-(3-chlorophenyl)-2-(4-chlorophenyl)-6-oxo-1-piperidinyl)butanoate as the faster eluting minor isomer: ¹H NMR (400 MHz, CHLOROFORM-d) δ ppm 7.22 (2 H, d, J = 8.2 Hz), 7.20-7.10 (2 H, m), 7.08 (2 H, t, J = 8.2 Hz) 6.99-6.96 (1 H, m), 6.77-6.73 (1 H, m), 4.48 (1 H, d, J = 9.4 Hz), 3.24 (1 H, t, J = 7.0 Hz), 3.04-2.94 (1 H, m), 2.72-2.58 (2 H, m), 2.25-2.00 (3 H, m), 1.93-1.82 (1 H, m), 1.45 (9 H, s), 0.98 (3 H, t, J = 7.4 Hz); MS (ESI) 462.1 [M + H]⁺.

Further elution provided tert-butyl (2R)-2-((2S,3R)-3-(3-chlorophenyl)-2-(4-chlorophenyl)-6-oxo-1-piperidinyl)butanoate as the slower eluting major isomer. ¹H NMR (400 MHz, CHLOROFORM-d) δ ppm 7.24 (2 H, d, J = 8.2 Hz), 7.18-7.10 (2 H, m), 7.01 (2 H , d, J = 8,2 Hz), 7.02-6.98 (1 H, m), 6.82-6.78 (1 H, m), 5.83 (1 H, s), 4.54 (1 H, d, J = 9.8 Hz), 3.09 (1 H, dd, J = 8.2, 4.3 Hz), 3.05-2.99 (1 H, m), 2.70-2.64 (2 H, m), 2.28-2.18 (2 H, m), 2.08-2.02 (1 H, m), 1.48 (9 H, s), 0.57 (3 H, t, J = 7.4 Hz); MS (ESI) 462.1 [M + H]⁺.

Step G. tert-Butyl (2S)-2-((3S,5R,6S)-3-allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-2-oxopiperidin-1-yl)butanoate and . tert-Butyl (2S)-2-((3R,5R,6S)-3-allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-2-oxopiperidin-1-yl)butanoate

To a solution of 1.45 g (3.14 mmol) of tert-butyl (2S)-2-((2S,3R)-3-(3-chlorophenyl)-2-(4-chlorophenyl)-6-oxo-1-piperidinyl)butanoate (Reference Example 1, Step F) and allyl bromide (0.326 mL, 3.76 mmol) in 12.5 mL of THF was added dropwise at -78 °C 3.3 mL of a 1 M solution of lithium bis(trimethylsilyl)-amide in THF (3.3 mmol). After being stirred at -78 °C for 3 h, the reaction was quenched with sat. aqueous NH₄Cl solution, extracted with ethyl acetate. The combined organic layers were washed with sat. NaCl solution, dried over Na₂SO₄, filtered and the filtrate was concentrated under reduced pressure. Purification of the residue by flash chromatography on silica gel (50g SiO₂, eluent: 5 to 20% EtOAc/hexanes, gradient elution) provided tert-butyl (2S)-2-((3R,5R,6S)-3-allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-2-oxopiperidin-1-yl)butanoate as the faster eluting major isomer. ¹H NMR (400 MHz, CHLOROFORM-d) δ ppm 7.27-7.24 (2 H, m), 7.21-7.12 (2 H, m), 7.11-7.00 (3 H, m), 6.93-6.87 (1 H, m), 5.90-5.77 (1 H, m), 5.19-5.09 (2 H, m), 4.64 (1 H, d, J = 8.6 Hz), 3.21-3.10 (2 H, m), 2.80-2.71 (1 H, m), 2.70-2.63 (1 H, m), 2.56-2.48 (1 H, m), 2.30-2.15 (2 H, m), 2.07-1.99 (1 H, m), 1.60-1.48 (1 H, m), 1.47 (9 H, s), 0.61 (3 H, t, J = 7.6 Hz); MS (ESI) 446.0 [M + H]⁺. Further elution provided tert-butyl (2S)-2-((3S,5R,6S)-3-allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-2-oxopiperidin-1-yl)butanoate as the slower eluting, minor isomer. ¹H NMR (400 MHz, CHLOROFORM-d) δ ppm 7.23 (2 H, d, J = 8.2 Hz), 7.19-7.07 (2 H, m), 7.01-6.95 (3 H, m), 6.77-6.72 (1 H, m), 5.95-5.77 (1 H, m), 5.16-4.99 (2 H, m), 4.51 (1 H, d, J = 10.6 Hz), 3.13-3.04 (1 H, m), 2.94 (1 H, dd, J=7.8, 4.3 Hz), 2.87-2.77 (1 H, m), 2.68-2.58 (1 H, m), 2.39-2.27 (2 H, m), 2.16-1.95 (2 H, m), 1.54-1.50 (1 H, m), 1.51 (9 H, s), 0.55 (3 H, t, J = 7.4 Hz); MS (ESI) 446.0 [M + H]⁺.

Step H. 2-((3R,5R,6S)-1-((S)-1-tert-Butoxy-1-oxobutan-2-yl)-5-(3-chlorophenyl)-6-(4-chlorophenyl)-2-oxopiperidin-3-yl)acetic acid

To a rapidly stirring solution of 842 mg (1.67 mmol) of tert-butyl (2S)-2-((3S, 5R, 6S)-3-allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-2-oxopiperidin-1-yl) butanoate (Reference Example 1, Step G) in a mixture of 7 mL of water, 5 mL of acetonitrile and 5mL of CCl₄ was added sodium periodate (1.43 g, 6.70 mmol), followed by ruthenium(III) chloride hydrate (37.8 mg, 0.168 mmol). After being stirred vigorously for 18 h, the reaction was acidified (10% citric acid) and diluted with EtOAc. The reaction mixture was filtered through celite and the filtrate was extracted with EtOAc. The combined organic layers were washed with sat. NaCl solution, dried over Na₂SO₄, filtered and the filtrate was concentrated under reduced pressure. The residue was purified by reversed phase preparatory HPLC (GeminiTM Prep C18 5 µm column, Phenomenex, Torrance, CA; eluent: 60 to 80% acetonitrile +0.1% TFA in water + 0.1% TFA, gradient elution) to give the title compound as a white solid. ¹H NMR (400 MHz, CHLOROFORM-d) δ ppm 7.35 (2 H, d, J = 8.6 Hz), 7.27-7.24 (3 H, m), 7.22-7.16 (1 H, m), 7.18 (2 H, d, J = 8.6 Hz), 4.85 (1 H, d, J = 5.1 Hz), 3.36 (1 H, dd, J= 8.6, 3.5 Hz), 3.18-3.14 (1 H, m), 2.92-2.80 (2 H, m), 2.79-2.72 (1 H, m), 2.32-2.18 (2 H, m), 2.15-2.06 (1 H, m), 1.63-1.50 (1 H, m), 1.44 (9 H, s), 0.67 (3 H, t, J = 7.4 Hz); MS (ESI) 520.2 [M + H]⁺, 518.0 [M - H]^-.

The following reference example 2 were prepared as described in Reference Example 1, substituting tert-butyl 2-bromobutanoate in step F, with the appropriate amount of ethyl 2-bromobutanoate, ethyl 2-bromo-3-methylpentanoate, ethyl 2-bromopentanoate, and ethyl 2-bromo-2-cyclopropylacetate, respectively.

REFERENCE EXAMPLE 2

2-((3R,5R,6S)-5-(3-Chlorophenyl)-6-(4-chlorophenyl)-1-((S)-1-ethoxy-1-oxobutan-2-yl)-2-oxopiperidin-3-yl)acetic acid

¹H NMR (400 MHz, CHLOROFORM-d) δ ppm 7.42-7.33 (3 H, m), 7.32-7.28 (3 H, m), 7.27-7.24 (2 H, m), 4.91 (1 H, d, J = 3.5 Hz), 4.23-4.10 (2 H, m), 3.54 (1 H, dd, J = 8.6, 3.5 Hz), 3.22-3.16 (1 H, m), 2.84-2.73 (3 H, m), 2.38-2.30 (2 H, m), 2.05-1.97 (1 H, m), 1.60-1.50 (1 H, m), 1.27 (3 H, t, J = 7.4 Hz), 0.70 (3 H, t, J = 7.4 Hz); MS (ESI) 491.8 [M + H]⁺, 489.9 [M - H]^-.

REFERENCE REFERENCE EXAMPLE 3

2-((3R,5R,6S)-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methyl-2-oxo-1-(pentan-3-yl)piperidin-3-yl)acetic acid Step A. (5R,6S)-5-(3-chlorophenyl)-6-(4-chlorophenyl)-1-(2,4-dimethoxybenzyl)piperidin-2-one.

Thionyl chloride (116 mL, 1586 mmol) was added dropwise over 1 hour to a turbid solution of (2,4-dimethoxyphenyl)methanol (97.00 g, 577 mmol) and pyridine (93 mL, 1153 mmol) in anhydrous Et₂O (1153 mL) at 0 °C under nitrogen with mechanical stirring. After 1 hour the reaction mixture was poured into 2 L of ice water and the layers were separated. The aqueous layer was extracted with Et₂O (2 x 1 L) and the organics were pooled, washed with ice water (1.2 L), cold 5:1 sat. aq. NaCl solution/sat. aq. NaHCO₃ (1.2 L), dried (MgSO₄), filtered and most of the ether was removed in vacuo at 12 °C. Benzene (300 mL) was added and the mixture was concentrated at 12 °C until 100 mL of benzene remained to provide a solution of 1-(chloromethyl)-2,4-dimethoxybenzene. 80g (250 mmol) of (5R,6S)-5-(3-chlorophenyl)-6-(4-chlorophenyl)piperidin-2-one (Reference Example 1, Step E) was added in portions over 20 minutes to a mixture of NaH (19.98 g, 500 mmol) in anhydrous DMF (400 mL) at 0 °C under nitrogen. After the addition was complete the ice bath was removed and the mixture was stirred at rt for 1 hour before cooling the solution to 0 °C. To the cooled solution was added a solution of 1-(chloromethyl)-2,4-dimethoxybenzene (107 g, 575 mmol) in benzene and the reaction mixture was allowed to warm to rt. After 16 hours the reaction mixture was poured into ice water (2 L) and extracted with EtOAc (3 x 1 L). The organics were pooled, washed with water (3 x 1 L), sat. aq. NaCl solution (1 L), dried (MgSO₄), filtered and concentrated in vacuo to provide a thick yellow oil. Purification on the Combiflash XL (flash column chromatography, Teledyne Isco, Lincoln, NE) using four stacked 330 g columns and one 1.5 kg column and eluting with 35-40-45-50-55% EtOAc/hexanes provided a very pale yellow oil. This was dissolved in benzene and the solvent removed in vacuo and dried under vacuum for 2 days to provide the title compound as a white foam (105.8 g, 90%).

Step B. (5R,6S)-5-(3-chlorophenyl)-6-(4-chlorophenyl)-1-(2,4-dimethoxybenzyl)-3-methylpiperidin-2-one.

A solution of (5R,6S)-5-(3-chlorophenyl)-6-(4-chlorophenyl)-1-(2,4-dimethoxybenzyl) piperidin-2-one (Reference Example 3, Step A) (140.34 g, 298 mmol) in anhydrous THF (994 mL) was degassed by bubbling argon through the solution for 20 minutes while it cooled to -78 °C. Iodomethane (23.32 mL, 373 mmol) was added followed by the addition of LHMDS (328 mL, 328 mmol) over 15 minutes. The reaction mixture was stirred for 15 minutes at -78 °C and then the reaction was removed from the cold bath and stirred at rt for 12 hours. The reaction was quenched by the addition of sat. aq. NH₄Cl and the layers were separated. The aqueous layer was extracted with EtOAc (2 x 500 mL) and the organics were pooled, washed with sat. aq. NaCl solution, dried (MgSO₄), filtered and concentrated in vacuo to provide an orange oil. Purification (wet loaded with small amount of DCM) using the Combiflash Companion XL (flash column chromatography, Teledyne Isco, Lincoln, NE) with a 1.5 kg SiO₂ column and eluting with 4 L each of 15-20-25-30-35% EtOAc/hexanes provided the title compound as a thick very pale yellow oil and a 3.7:1 mixture of C-3 diastereomers.

Step C. (5R,6S)-3-allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-1-(2,4-dimethoxybenzyl)-3-methylpiperidin-2-one.

A solution of (5R,6S)-5-(3-chlorophenyl)-6-(4-chlorophenyl)-1-(2,4-dimethoxybenzyl)-3-methylpiperidin-2-one (Reference Example 3, Step B, mixture of C-3 diastereomers) (117.0 g, 242 mmol) in anhydrous THF (966 mL) was degassed by bubbling argon through the solution for 20 minutes. Allyl bromide (105 mL, 1208 mmol) was added followed by the addition of LHMDS (725 mL, 725 mmol) over 20 minutes. The reaction mixture was heated at 40 °C under argon for 5 hours. The reaction mixture was cooled to rt. and the reaction was quenched by the addition of sat. aqueous NH₄Cl (500 mL) and the layers were separated. The aqueous layer was extracted with EtOAc (2 x 1 L) and the organics were pooled, washed with sat. aq. NaCl solution (1 L), dried (MgSO₄), filtered and concentrated in vacuo to provide a red oil (180 g). Purification using the Biotage system (Charlotte, NC) with a 1.5 kg SiO₂ column and eluting with 10-30% EtOAc/hexanes provided the title compound as a very pale yellow oil as a 3.7:1 mixture of (3S):(3R) diastereomers..

Step D. (3S,5R,6S)-3-allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methylpiperidin-2-one.

A solution of (5R,6S)-3-allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-1-(2,4-dimethoxybenzyl)-3-methylpiperidin-2-one (Reference Example 3, Step C, mixture of diastereomers) (105.87 g, 202 mmol) in TFA (778 mL, 1.01E+04 mmol) was heated at 50 °C for 2 hours before concentrating the reaction mixture in vacuo. The residue was azeotroped with hexanes to remove all of the TFA. The deep purple oil containing some residue was taken up in a minimum amount of DCM, filtered and washed liberally with DCM. The filtrate was concentrated in vacuo to provide a dark purple oil. Purification (wet packed with a minimum amount of DCM) using the Biotage Isolera (Biotage, Charlotte, NC) with a 1.5 kg column and eluting with 25-40% EtOAc/hexanes provided the title compound as a white solid. ¹H NMR (500 MHz, CDCl₃) δ ppm 1.30 (s, 3H), 2.06 (m, 2H), 2.52 (dd, J = 13.7 and 7.1 Hz, 1H), 2.60 (dd, J = 13.7 and 7.8 Hz, 1H), 3.06 (m, 1H), 4.50 (d, J = 10.7 Hz, 1H), 5.17 (m, 2H), 5.81 (br s, 1H), 5.86 (m, 1H), 6.77 (d, J = 7.6 Hz, 1H), 6.96 (d, J = 8.3 Hz, 2H), 7.00 (s, 1H), 7.12 (t, J = 7.7 Hz, 1H), 7.17 (m, 1H), 7.20 (d, J = 8.3 Hz, 2H). [□]²² _D +182.2° (c 1.55, CHCl₃).

Step E. (3S,5R,6S)-3-allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methyl-1-(pentan-3-yl)piperidin-2-one

To a suspension of 1.81 g (4.8 mmol) of (3S,5R,6S)-3-allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methylpiperidin-2-one (Reference Example 3, Step D) in 3-bromopentane (17.6 mL) added 967 mg (60 wt. % in mineral oil, 24.2 mmol) of sodium hydride. The resulting milky white slurry was heated at 120 °C for 20 h, and then more 3-bromopentane (5.1 mL) was added. After an additional 24 h at 120 °C, the reaction was cooled to room temperature and quenched with saturated aqueous ammonium chloride. The mixture was extracted with ethyl acetate (3X) and the combined organic layers were dried over Na₂SO₄, filtered and the filtrate was concentrated. Purification of the residue by flash chromatography on silica gel (2 to 26% EtOAc/hexanes, gradient elution) provided the title compound as a white solid.

Step F. Synthesis of 2-((3R,5R,6S)-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methyl-2-oxo-1-(pentan-3-yl)piperidin-3-yl)acetic acid

To a solution of 725 mg (1.63 mmol) of (3S,5R,6S)-3-allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methyl-1-(pentan-3-yl)piperidin-2-one (Reference Example 2, Step A) in a mixture of acetonitrile (4 mL), carbon tetrachloride (4 mL) and water (5.9 mL) added 1.40 g (6.53 mmol) of sodium periodate followed by 44 mg (0.20 mmol) of ruthenium(III) chloride hydrate. The dark brown biphasic mixture was stirred vigorously at room temperature for 21 h, and then was acidified with 1 N HCl. The mixture was diluted with EtOAc and filtered through a pad of Celite® (J.T. Baker, Phillipsberg, NJ, diatomaceous earth). After filtration, the layers were separated and the aqueous layer was extracted with EtOAc (1X). The combined organic layers were washed with saturated aqueous sodium chloride (1X), then were dried over Na₂SO₄, filtered and the filtrate was concentrated. Purification of the residue by flash chromatography on silica gel (0 to 25% MeOH/DCM, gradient elution) provided the title compound as a white solid. ¹H NMR (400 MHz, CDCl₃) δ ppm 7.06-7.27 (5 H, m), 6.90-7.01 (2 H, m), 6.68 (d, 1 H, J = 7.8 Hz), 4.34 (1 H, d, J = 10.4 Hz), 3.00-3.15 (2 H, m), 2.63-2.79 (2 H, m), 2.15-2.27 (1 H, m), 1.85-2.03 (3 H, m), 1.51 (s, 3 H), 1.38-1.51 (2 H, m), 0.95 (3 H, t, J = 7.4 Hz), 0.50 (3 H, t, J = 7.4 Hz). Mass Spectrum (ESI) m/z = 462 (M+1).

REFERENCE EXAMPLE 4 2-((3R,5R,6S)-5-(3-Chlorophenyl)-6-(4-chlorophenyl)-3-methyl-1-((S)-1-morpholinobutan-2-yl)-2-oxopiperidin-3-yl)acetic acid

Step A. (S)-Methyl 2-((3S,5R,6S)-3-allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methyl-2-oxopiperidin-1-yl)butanoate

To a solution of (3S,5R,6S)-3-allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methylpiperidin-2-one (Reference Exampe 3, Step D) (4.00 g, 10.7 mmol) in 45 mL of DMF was added a dispersion of 60% sodium hydride in mineral oil (1.71 g, 42.7 mmol) at 0 °C. After being stirred for 20 min, methyl 2-bromobutanoate (6.15 mL, 53.4 mmol) was added at 0 °C and the resulting solution was stirred at 25 °C for 12 h until completion of the reaction. Then sat. aq. NH₄Cl solution was added and the mixture was extracted with ethyl acetate. The combined organic layers were washed with water and sat. aq. NaCl solution, dried over Na₂SO₄, filtered and the filtrate was concentrated under reduced pressure. Purification of the residue by flash chromatography on silica gel (eluent: 0 to 100% MTBE/hexanes, gradient elution), followed by separation of individual stereoisomers by chiral SFC (flowrate: 65 mL/min on a ChiralPak ®AD-H column (Diacel Inc., Fort Lee, NJ) using 3:1 heptanes / IPA (0.1% DEA) / CO₂ as the eluent) provided the title compound as the faster eluting isomer. ¹H NMR (400 MHz, CHLOROFORM-d) δ ppm 7.23 (2 H, d, J = 8.4 Hz), 7.06 - 7.17 (2 H, m), 7.00 (3 H, t, J = 1.8 Hz), 6.77 (1 H, d, J = 7.6 Hz), 5.79 - 5.94 (1 H, m), 5.20 (1 H, d, J = 4.7 Hz), 5.17 (1 H, s), 4.56 (1 H, d, J = 10.8 Hz), 3.73 (3 H, s), 3.25 - 3.37 (1 H, m), 3.18 (1 H, dd, J = 7.6 Hz, 4.9 Hz), 2.61 (2 H, d, J = 7.4 Hz), 2.20 - 2.34 (1 H, m), 2.09 - 2.19 (1 H, m), 1.99 (1 H, d, J = 3.1 Hz), 1.57 - 1.72 (1 H, m), 1.24 (3 H, s), 0.61 (3 H, t, J = 7.5 Hz); Mass Spectrum (ESI) m/z = 474.1 [M+H]⁺. Further elution provided: (R)-Methyl 2-((3S,5R,6S)-3-allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methyl-2-oxopiperidin-1-yl)butanoate as the slower eluting isomer. ¹H NMR (400 MHz, CHLOROFORM-d) δ ppm 7.22 (2 H, d, J = 8.0 Hz), 6.99 - 7.19 (4 H, m), 6.95 (1 H, t, J = 1.8 Hz), 6.71 (1 H, d, J = 7.6 Hz), 5.81 - 5.95 (1 H, m), 5.19 (1 H, d, J = 2.7 Hz), 5.16 (1 H, d, J = 1.0 Hz), 4.48 (1 H, d, J = 10.6 Hz), 3.67 (3 H, s), 3.24 - 3.32 (1 H, m), 3.20 (1 H, dd, J = 7.8 Hz, 6.1 Hz), 2.61 - 2.72 (1 H, m), 2.49 - 2.60 (1 H, m), 1.91 - 2.21 (4 H, m), 1.27 (3 H, s), 1.00 (3 H, t, J = 7.5 Hz); MS (ESI) m/z = 474.1 [M+H]⁺.

Step B. (3S,5R,6S)-3-Allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-1-((R)-1-hydroxybutan-2-yl)-3-methylpiperidin-2-one

To a solution of (S)-methyl 2-((3S,5R,6S)-3-allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methyl-2-oxopiperidin-1-yl)butanoate and (R)-methyl 2-((3S,5R,6S)-3-allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methyl-2-oxopiperidin-1-yl)butanoate (1.73 g, 3.64 mmol) (mixture of stereoisomers from Reference Example 4, Step A) in 27 mL of Et₂O and 9 mL of THF was added a solution of lithium tetrahydroborate in THF (0.238 mL, 7.28 mmol) at 0 °C. The resulting solution was stirred at 25 °C for 2 h. The reaction was quenched (10% citric acid), extracted (2 × EtOAc) and washed (1 × Sat. aq. NaCl solution). The combined organic layers were washed with sat. aq. NaCl solution, dried over Na₂SO₄, filtered and the filtrate was concentrated under reduced pressure. The residue was purified by flash chromatography on silica gel (eluent: 0-60% EtOAc in hexanes) to give the title compound as the faster eluting isomer. ¹H NMR (400 MHz, CHLOROFORM-d) δ ppm 0.99 (t, J = 7.4 Hz, 3 H), 1.29 (s, 3 H), 1.79 - 2.03 (m, 4 H), 2.62 (d, J = 7.4 Hz, 2 H), 2.80 - 2.85 (m, 1 H), 3.05 - 3.16 (m, 1 H), 3.40 - 3.49 (m, 2 H), 4.33 (d, J = 10.4 Hz, 1 H), 5.13 - 5.22 (m, 2 H), 5.79 - 5.95 (m, 1 H), 6.7 (d, J = 7.6 Hz, 1 H), 6.85 - 6.97 (m, 3 H), 7.08 - 7.15 (m, 1 H), 7.17 - 7.19 (m, 1 H), 7.23 (d, J = 8.6 Hz, 2 H); Mass Spectrum (ESI) m/z = 446 (M+1). Further elution provided: (3S,5R,6S)-3-Allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-1-((S)-1-hydroxybutan-2-yl)-3-methylpiperidin-2-one as the slower eluting isomer. ¹H NMR (400 MHz, CHLOROFORM-d) δ ppm 0.68 (t, J = 7.5 Hz, 3 H), 1.27 (s, 3 H), 1.38 - 1.52 (m, 1 H), 1.90 - 2.08 (m, 4 H), 2.61 (d, J = 7.4 Hz, 2 H), 3.10 - 3.25 (m, 2 H), 3.59 - 3.68 (m, 2 H), 4.46 (d, J = 10.2 Hz, 1 H), 5.18 (dd, J = 13.7, 1.8 Hz, 2 H), 5.79 - 5.93 (m, 1 H), 6.72 (d, J = 7.6 Hz, 1 H), 6.93 - 7.04 (m, 2 H), 7.09 - 7.13 (m, 1 H), 7.15 - 7.20 (m, 1 H), 7.24 (d, J = 8.6 Hz, 2 H); Mass Spectrum (ESI) m/z = 446 (M+1).

Step C. (S)-2-((3S,5R,6S)-3-Allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methyl-2-oxopiperidin-1-yl)butanal

To a solution of 218 mg (0.49 mmol) of (3S,5R,6S)-3-allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-1-((S)-1-hydroxybutan-2-yl)-3-methylpiperidin-2-one (Reference Example 4, Step B) in a micture of water (13.20 µL, 0.733 mmol) and DCM (4883 µL) was added 1,1,1,-tris(acetoxy)-1,1-dihydro-1,2-benziodoxol-3-(1H)one ("Dess Martin periodinane") (311 mg, 0.733 mmol) at ambient temperature. The reaction was monitored by LCMS, and several small portions of additional periodinane were added until the reaction was complete. The reaction was quenched (2 mL, 1 M Na₂S₂O₃), extracted (2 x DCM), and the combined organic layers were washed with sat. NaHCO₃ solution (2X), sat NaCl solution, dried over Na₂SO₄, filtered and the filtrate was concentrated under reduced pressure. Purication of the residue by flash chromatography on silica gel (eluent: 20 to 35% EtOAc/hexanes, gradient elution) provided the title compound.

Step D. (3S,5R,6S)-3Allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methyl-1-((S)-1-morpholinobutan-2-yl)piperidin-2-one.

To a solution of 100 mg (0.225 mmol) of (S)-2-((3S,5R,6S)-3-allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methyl-2-oxopiperidin-1-yl)butanal (Reference Example 4, Step C) in DCE (2420 µL) was addded morpholine (200 µL, 2.297 mmol), acetic acid (1.288 µL, 0.023 mmol) and sodium triacetoxyborohydride (95 mg, 0.450 mmol). The reaction mixture was stirred at room temperature for 18 hours. The reaction was quenched with sat. sodium bicarbonate solution and extracted with DCM (2x10 mL). The combined organic layers were washed with sat NaCl solution, dried over Na₂SO₄, filtered and the filtrate was concentrated under reduced pressure to afford the crude title compound as an oil.

Step E. 2-((3R,5R,6S)-5-(3-Chlorophenyl)-6-(4-chlorophenyl)-3-methyl-1-((S)-1-morpholinobutan-2-yl)-2-oxopiperidin-3-yl)acetaldehyde.

To a round-bottomed flask charged with (3S,5R,6S)-3-allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methyl-1-((S)-1-morpholinobutan-2-yl)piperidin-2-one (Reference Example 4, Step D) (125 mg, 0.242 mmol) was added THF (2 mL). Approximately 1 mL water was added dropwise until the solution became and remained cloudy with gentle stirring. t-BuOH (0.350 mL) was added dropwise until the solution became homogeneous. NMO (42.6 mg, 0.364 mmol) was added followed by osmium tetroxide, 4 wt. %, in water (1 drop from glass Pasteur pipette). The reaction mixture was stirred at room temperature for 16 hours. An additional drop of osmium tetroxide, 4 wt. %, in water was added. After 5 hours, two additional drops of osmium tetroxide, 4 wt. %, in water were added and the reaction mixture was stirred at room temperature for an additional 16 hours. Sodium periodate (145 mg, 0.679 mmol) was added and the reaction mixture was stirred at room temperature for 2 hours. The reaction mixture was diluted with ethyl acetate (10 mL) and water (10 mL) and filtered. The aqueous layer of the filtrate was extracted with additional ethyl acetate (10 mL) and the combined organic layers were washed with sat. aq. NaCl solution, dried over sodium sulfate, filtered and the filtrate was concentrated under reduced pressure to provide the title compound.

Step F. 2-((3R,5R,6S)-5-(3-Chlorophenyl)-6-(4-chlorophenyl)-3-methyl-1-((S)-1-morpholinobutan-2-yl)-2-oxopiperidin-3-yl)acetic acid

To a solution of 2-((3R,5R,6S)-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methyl-1-((S)-1-morpholinobutan-2-yl)-2-oxopiperidin-3-yl)acetaldehyde (Reference Example 4, Step E) (125 mg, 0.242 mmol) in acetone (2 mL) was added 3 mL of a mixture of CrO₃ in water (2 mL) and concentrated H₂SO₄ (1 ml). The reaction mixture was stirred at room temperature for 2 hours and then diluted with water (10 mL) and ethyl acetate (10 mL) and the layers were separated. The aqueous layer was extracted with additional ethyl acetate (10 mL). The combined organic layers were concentrated under reduced pressure. The residue was purified by reversed phase preparatory HPLC (column: Gemini-NX C₁₈ 5um column; Phenomonex, Torrance, CA; eluent: 0 to 100% MeCN +0.1% TFA in water + 0.1% TFA) to provide the title compound. ¹H NMR (400 MHz, CHLOROFORM-d) δ ppm 0.57 (t, J = 7.53 Hz, 1 H) 1.26 (s, 1 H) 1.39 (s, 3 H) 1.54 - 1.70 (m, 1 H) 1.72 - 1.89 (m, 1 H) 2.02 - 2.27 (m, 3 H) 2.49 (br. s., 2 H) 2.69 (br. s., 2 H) 2.82 (m, 2 H) 3.02 (br. s., 2 H) 3.13 - 3.30 (m, 2 H) 3.74 - 3.93 (m, 4 H) 4.47 - 4.72 (m, 1 H) 6.75 (d, J = 7.82 Hz, 1 H) 6.96 (t, J = 1.86 Hz, 1 H) 7.01 (br. s., 1 H) 7.04 - 7.17 (m, 3 H) 7.22 (d, J = 8.41 Hz, 2 H). Mass Spectrum (ESI) m/z = 533 [M + H]⁺.

REFERENCE EXAMPLE 5 2-((3R,5R,6S)-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methyl-1-((S)-1-(methylsulfonamido)butan-2-yl)-2-oxopiperidin-3-yl)acetic acid

Step A. (3R,5R,6S)-3-allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-1-((S)-1-((4-methoxybenzyl)amino)butan-2-yl)-3-methylpiperidin-2-one

To a solution of (S)-2-((3R,5R,6S)-3-allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methyl-2-oxopiperidin-1-yl)butanal (300 mg, 0.675 mmol; Reference Example 4, Step C) and (4-methoxyphenyl)methanamine (131 µL, 1.01 mmol) in DCE (4.5 mL) was added sodium triacetoxyborohydride (429 mg, 2.03 mmol) at 0 °C in several portions. After being stirred at 25 °C for 18 h, the reaction was quenched by adding ice-cold saturated aqueous NaHCO₃ and extracted (2×DCM). The combined organic layers were washed (1×sat. aq. NaCl solution) and concentrated under reduced pressure to provide the title compound as a yellow film. The product was used in the next step without further purification.

Step B. (S)-2-((3S,5R,6S)-3-Allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methyl-2-oxopiperidin-1-yl)butan-1-ammonium 2,2,2-trifluoroacetate

To a solution of (3S,5R,6S)-3-allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-1-((S)-1-(4-methoxybenzylamino)butan-2-yl)-3-methylpiperidin-2-one (370 mg, 0.654 mmol; Reference Example 5, Step A) in acetonitrile (8.0 mL) and water (1.6 mL) was added ceric ammonium nitrate (2.87 g, 5.23 mmol) at 25 °C. After being stirred at rt for 2 days, the reaction was quenched (sat. aq. NaCl solution), extracted (3×EtOAc), and washed (1×sat. aq. NaCl solution). The combined organic layers were dried (Na₂SO₄) and concentrated under reduced pressure. Purification by RP-HPLC (35 to 70% MeCN/H₂O (0.1% TFA), a gradient elution) provided the title compound as a pale yellow powder.

Step C. N-((S)-2-((3S,5R,6S)-3-Allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methyl-2-oxopiperidin-1-yl)butyl)methanesulfonamide

(S)-2-((3S,5R,6S)-3-allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methyl-2-oxopiperidin-1-yl)butan-1-aminium 2,2,2-trifluoroacetate (74 mg, 0.14 mmol; Reference Example 5, Step B) was dissolved in DCM at 0 °C and 2 N lithium hydroxide (0.34 mL, 0.68 mmol) was added and the resulting solution was stirred for 5 min at 0 °C. The solution was extracted (2×DCM), washed (sat. aq. NaCl solution), dried (Na₂SO₄), and concentrated under reduced pressure to give the free amine. To a solution of the free amine from above in DMF (0.34 mL) was added methanesulfonyl chloride (53 µL, 0.68 mmol) and pyridine (66 µL, 0.820 mmol) successively at 0 °C. After being stirred at 25 °C for overnight, the reaction was acidified (10% citric acid) and extracted (2×EtOAc) and washed (sat. aq. NaCl solution). The combined organic layers were dried (Na₂SO₄), and concentrated under reduced pressure. Purification by RP-HPLC (45 to 80% MeCN/H₂O (0.1% TFA), a gradient elution) provided the title compound as a white powder.

Step D. 2-((3R,5R,6S)-5-(3-Chlorophenyl)-6-(4-chlorophenyl)-3-methyl-1-((S)-1-(methylsulfonamido)butan-2-yl)-2-oxopiperidin-3-yl)acetic acid

To a rapidly stirring solution of N-((S)-2-((3S,5R,6S)-3-allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methyl-2-oxopiperidin-1-yl)butyl)methanesulfonamide (34 mg, 0.064 mmol; Reference Example 4, Step C) in a mixture of water (0.55 mL), acetonitrile (0.37 mL), and CCl₄ (0.37 mL) was added sodium periodate (55 mg, 0.26 mmol) and ruthenium(III) chloride hydrate (1.5 mg, 6.5 µmol). After being stirred vigorously for 20 h, the reaction was acidified (10% citric acid) and diluted with EtOAc. The insoluble material was removed by filtering through a pad of Celite® (J.T. Baker, Phillipsberg, NJ, diatomaceous earth). The filtrate was extracted (2×EtOAc) and washed (sat. aq. NaCl solution). The combined organic layers were dried (Na₂SO₄) and concentrated under reduced pressure. Purification by RP-HPLC (40 to 70% MeCN/H₂O (0.1% TFA), a gradient elution) provided the title compound as a white foam. ¹H NMR (400 MHz, CHLOROFORM-d) δ ppm 7.25 (2 H, d, J = 8.2 Hz), 7.10 - 7.18 (2 H, m), 7.00 - 7.10 (2 H, m), 6.97 (1 H, s), 6.83 (1 H, d, J = 7.2 Hz), 4.99 - 5.20 (1 H, m), 4.87 - 4.97 (1 H, m), 4.74 (1 H, d, J = 10.4 Hz), 3.44 - 3.65 (1 H, m), 3.10 - 3.33 (2 H, m), 3.02 - 3.09 (1 H, m), 2.99 (3 H, s), 2.96 (1 H, s), 2.77 (1 H, s), 2.36 (1 H, s), 1.94 - 2.05 (1 H, m), 1.77 - 1.92 (1 H, m), 1.52 - 1.59 (1 H, m), 1.50 (3 H, s), 0.58 (3 H, t, J = 7.3 Hz); MS (ESI) 541.0 [M+H]⁺, 539.0 [M-H]^-.

REFERENCE EXAMPLE 6 2-((3R,5R,6S)-5-(3-Chlorophenyl)-6-(4-chlorophenyl)-1-((3S,4R)-5-hydroxy-4,5-dimethylhexan-3-yl)-3-methyl-2-oxopiperidin-3-yl)acetic acid or 2-((3R,5R,6S)-5-(3-Chlorophenyl)-6-(4-chlorophenyl)-1-((3S,4S)-5-hydroxy-4,5-dimethylhexan-3-yl)-3-methyl-2-oxopiperidin-3-yl)acetic acid

Step A. (3S,5R,6S)-3-Allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methyl-1-((S)-2-oxopentan-3-yl)piperidin-2-one

To a solution of oxalyl dichloride (78 µL, 0.87 mmol) in DCM (1.5 mL) at -60 °C was added a solution of DMSO (93 µL, 1.30 mmol) in DCM (1.5 mL) under N₂. After being stirred for 2 min, a solution of (3S,5R,6S)-3-allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-1-((3S)-2-hydroxypentan-3-yl)-3-methylpiperidin-2-one prepared in reference example 7, Step C (200 mg, 0.434 mmol) in DCM (1.5 mL) was added and the resulting solution was stirred for 15 min.at -60 °C. Then, triethylamine (305 µL, 2.17 mmol) was added to the reaction solution. After being stirred at rt for 20 min, the reaction was quenched (water), extracted (2×EtOAc), and washed (2×sat. aq. NaCl solution). The combined organic layers were dried (Na₂SO₄) and concentrated under reduced pressure. Purification by combi flash (SiO₂, 24 g, 20% and 30% EtOAc/Hexanes) provided the title compound as a colorless foam.

Step B. ((3S,5R,6S)-3-Allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-1-((S)-1-methoxy-2-methylpent-1-en-3-yl)-3-methylpiperidin-2-one

(Methoxymethyl)triphenylphosphonium chloride was dried at 80 °C under vacuum for 2 h. To a solution of the dried (methoxymethyl)triphenylphosphonium chloride (673 mg, 1.96 mmol) in THF (3.5 mL) was added 0.5 M KHMDS in toluene (3.49 mL, 1.75 mmol) at -78 °C. The solution resulted in a blood red color. After addition, the reaction was stired at 0 °C for 30 min and a solution of (3S,5R,6S)-3-allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methyl-1-((S)-2-oxopentan-3-yl)piperidin-2-one prepared above in Step B (200 mg, 0.436 mmol) in THF (3.5 mL) was added dropwisely at 0 °C. The reaction was allowed to warm to rt and stirred for 1.5 h. Then the reaction was quenched (sat NH₄Cl solution), extracted (2×EtOAc), and washed (brine). The combined organic layers were dried (Na₂SO₄) and concentrated under reduced pressure. Purification by combi flash (SiO₂, 24 g, 15% and 20% EtOAc/Hexanes) provided the title compound as a colorless film.

Step C. (2S,3S)-3-((3S,5R,6S)-3-Allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methyl-2-oxopiperidin-1-yl)-2-methylpentanal and (2R,3S)-3-((3S,5R,6S)-3-Allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methyl-2-oxopiperidin-1-yl)-2-methylpentanal

To a solution of (3S,5R,6S)-3-allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-1-((S)-1-methoxy-2-methylpent-1-en-3-yl)-3-methylpiperidin-2-one prepared above in Step B (179 mg, 0.368 mmol) in acetonitrile (3.7 mL) was added 3 N hydrochloric acid (1.5 mL, 4.5 mmol) at rt. After being stirred at rt for 1.5 h, the reaction was extracted (2×EtOAc), and washed (2×brine). The combined organic layers were dried (Na₂SO₄) and concentrated under reduced pressure provided the title compounds as a mixture of stereoisomers (dr = 7:3) as a pale yellow film.

Step D. (3S,5R,6S)-3-allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methyl-1-((3S,4R)-4-methyl-5-oxohexan-3-yl)piperidin-2-one and (3S,5R,6S)-3-allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methyl-1-((3S,4S)-4-methyl-5-oxohexan-3-yl)piperidin-2-one

To a solution of (2S,3S)-3-((3S,5R,6S)-3-allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methyl-2-oxopiperidin-1-yl)-2-methylpentanal and (2R,3S)-3-((3S,5R,6S)-3-allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methyl-2-oxopiperidin-1-yl)-2-methylpentanal prepared above in Step C (177 mg, 0.375 mmol) in THF (3.076 ml) was added 1.4 M methylmagnesium bromide in toluene and THF (75:25) (0.803 ml, 1.12 mmol) at 0 °C. Then the reaction was allowed to warm to rt and stirred for 2 h. The reaction was quenched (sat NH₄Cl solution), extracted (2×EtOAc), and washed (brine). The combined organic layer was dried (Na₂SO₄) and concentrated under the reduced pressure to provide a crude seconday alcohol product.

To a solution of the crude seconday alcohol product (183 mg, 0.375 mmol) in DCM (4.2 mL) was added water (14 µL, 0.75 mmol) and dess-martinperiodinane (196 mg, 0.462 mmol) successiviely. After being stirred ar rt for overnight, the reaction was quenched (1 M aq. Na₂S₂O₃), extracted (2×DCM), and washed (2×sat. NaHCO₃ and 1×brine). The combined organic layers were dried (Na₂SO₄) and concentrated under reduced pressure. Purification of the residue by chromatography on silica gel (24 g SiO₂, 13%, 27% and 37% EtOAc/Hex) provided a less polar and more polar isomer, successively.

Less polar isomer: ¹H NMR (400 MHz, CHLOROFORM-d) δ ppm 7.25 (2 H, d, J = 8.0 Hz), 7.03 - 7.17 (4 H, m), 6.94 - 6.99 (1 H, m), 6.81 - 6.87 (1 H, m), 5.12 - 5.23 (2 H, m), 4.58 (1 H, d, J = 10.8 Hz), 3.14 (1 H, s), 2.66 (1 H, s), 2.58 (2 H, d, J = 7.4 Hz), 2.22 (3 H, s), 1.81 (1 H, d, J = 4.3 Hz), 1.75 (1 H, d, J = 7.2 Hz), 1.51 - 1.65 (2 H, m), 1.19 (3 H, s), 1.00 (3 H, d, J = 7.2 Hz), 0.30 (3 H, t, J = 7.7 Hz); MS (ESI) 486.1 [M+H]⁺.

More polar isomer: ¹H NMR (400 MHz, CHLOROFORM-d) δ ppm 7.22 - 7.27 (2 H, m), 7.01 - 7.17 (4 H, m), 6.89 - 6.95 (1 H, m), 6.71 (1 H, dt, J = 7.5, 1.3 Hz), 5.81 - 5.93 (1 H, m), 5.17 - 5.25 (2 H, m), 4.32 (1 H, d, J = 10.8 Hz), 3.50 (1 H, br. s.), 3.23 - 3.32 (1 H, m), 3.06 (1 H, br. s.), 2.60 - 2.66 (2 H, m), 2.13 - 2.20 (3 H, m), 1.91 - 2.01 (2 H, m), 1.64 - 1.70 (2 H, m), 1.28 - 1.32 (3 H, m), 1.13 (3 H, d, J = 7.0 Hz), 0.34 (3 H, t, J = 7.5 Hz); MS (ESI) 486.1 [M+H]⁺.

Step E. (3S,5R,6S)-3-Allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-1-((3S,4R)-5-hydroxy-4,5-dimethylhexan-3-yl)-3-methylpiperidin-2-one or (3S,5R,6S)-3-Allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-1-((3S,4S)-5-hydroxy-4,5-dimethylhexan-3-yl)-3-methylpiperidin-2-one

To a solution of the less polar isomer prepared above in reference example 6, step D (96 mg, 0.20 mmol) in THF (2.0 mL) was added 1.4 M methylmagnesium bromide in toluene and THF (75:25) (423 µL, 0.592 mmol) at 0 °C. Then the reaction was allowed to warm to rt and stirred for overnight. The reaction was quenched (sat NH₄Cl solution), extracted (2×EtOAc), and washed (brine). The combined organic layers were dried (Na₂SO₄) and concentrated under reduced pressure. Purification of the residue by combi-flash (12 g SiO₂, 30% EtOAc/Hex) provided the title compound as a single isomer.

Step F. 2-((3R,5R,6S)-5-(3-Chlorophenyl)-6-(4-chlorophenyl)-1-((3S,4R)-5-hydroxy-4,5-dimethylhexan-3-yl)-3-methyl-2-oxopiperidin-3-yl)acetic acid or 2-((3R,5R,6S)-5-(3-Chlorophenyl)-6-(4-chlorophenyl)-1-((3S,4S)-5-hydroxy-4,5-dimethylhexan-3-yl)-3-methyl-2-oxopiperidin-3-yl)acetic acid

The title compound was prepared from (3S,5R,6S)-3-allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-1-((3S,4R)-5-hydroxy-4,5-dimethylhexan-3-yl)-3-methylpiperidin-2-one or (3S,5R,6S)-3-allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-1-((3S,4S)-5-hydroxy-4,5-dimethylhexan-3-yl)-3-methylpiperidin-2-one (Reference Example 6, Step E) by a procedure similar to the one described in reference example 5, Step D. ¹H NMR (400 MHz, CHLOROFORM-d) δ ppm 7.01 - 7.27 (6 H, m), 6.96 (1 H, t, J = 1.7 Hz), 6.70 (3 H, d, J = 7.6 Hz), 4.59 (1 H, d, J = 9.8 Hz), 3.63 - 3.91 (1 H, m), 3.14 (1 H, s), 2.98 (1 H, d, J = 14.5 Hz), 2.72 (1 H, d, J = 14.5 Hz), 1.98 - 2.21 (2 H, m), 1.84 - 1.96 (1 H, m), 1.56 - 1.69 (2 H, m), 1.48 (3 H, s), 1.15 (3 H, s), 1.06 (3 H, s), 0.75 (3 H, br. s.), 0.28 (3 H, br. s.); MS (ESI) 520.2 [M+H]⁺, 518.2 [M-H]^-.

REFERENCE EXAMPLE 7 2-((3R,5R,6S)-5-(3-Chlorophenyl)-6-(4-chlorophenyl)-3-methyl-2-oxo-1-((S)-2-oxopentan-3-yl)piperidin-3-yl)acetic acid

Step A. (3S,5R,6S)-3-Allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-1-((S)-1-hydroxybutan-2-yl)-3-methylpiperidin-2-one

To a solution of 1004 g (1.47 mol) of (3S,5R,6S)-3-allyl-1-((S)-1-((tert-butyldiphenylsilyl)oxy)butan-2-yl)-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methylpiperidin-2-one (Reference Example 9, Step E) in THF (3.0 L) was added 2.50 L (2.50 mol) of a 1 M solution of TBAF in THF over a 10 min period. The orange solution was stirred at room temperature for 4 h. The reaction was quenched with 1 N HCl (3 L) and extracted with EtOAc (3X). The combined organic layers were washed with a 3:1 mixture of water and saturated aqueous sodium chloride (4X) and then saturated aqueous sodium chloride (1X). The organic layer was dried over Na₂SO₄, filtered and the filtrate was concentrated. Purification of the residue by chromatography (Biotage® Snap™ column; Biotage, LLC, Charlotte, NC), 10 to 50% EtOAc/hexanes, where the EtOAc contains 2% MeCN, gradient elution) provided the title compound as a white foam.

Step B. (S)-2-((3S,5R,6S)-3-Allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methyl-2-oxopiperidin-1-yl)butanal

To a solution of 428 g (959 mmol) of (3S,5R,6S)-3-allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-1-((S)-1-hydroxybutan-2-yl)-3-methylpiperidin-2-one (Reference Example 7, Step A) in dichloromethane (4.55 L) was added 25.9 mL (1.44 mol) of water. A solution of 610 g (1.44 mol) of Dess-Martin periodinane in dichloromethane (4.55 L) was added slowly over a 25 min period so as to maintain an internal reaction temperature not exceeding 25 °C. The white slurry was stirred for 2.5 h and then was quenched by cautious, slow addition of saturated aqueous sodium thiosulfate (5.2 L) so as to maintain an internal reaction temperature below 30 °C. Water was added and the mixture was extracted with dichloromethane (3 X). The combined organic layers were washed with saturated aqueous sodium bicarbonate solution (4X) and then saturated aqueous sodium chloride (1X), dried over Na₂SO₄, filtered and the filtrate was concentrated to afford a yellow oily solid. A mixture of ethyl ether and DCM were added, and precipitated solids were filtered off. The precipitation/filtration process was repeated. The filtrate was concentrated to provide the title compound as a white solid. The crude product was used directly in the next step.

Step C. (3S,5R,6S)-3-Allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-1-((3S)-2-hydroxypentan-3-yl)-3-methylpiperidin-2-one

To a 0 °C solution of 399 g (899 mmol) of (S)-2-((3S,5R,6S)-3-allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methyl-2-oxopiperidin-1-yl)butanal (Reference Example 7, Step B) in THF (9 L) was added 1.93 L (2.70 mol) of a 1.4 M solution of methylmagnesium bromide 75:25 in toluene/tetrahydrofuran slowly over a 30 min period so as to maintain an internal reaction temperature below 6 °C. The yellow solution was warmed to room temperature and stirred for 1.5 h. At this time the reaction was cooled to 0 °C and quenched by cautious, slow addition of saturated aqueous ammonium chloride (4.6 L) so as to maintain an internal reaction temperature below 15 °C. The mixture was warmed to room temperature, ethyl acetate was added, and the layers were separated. The aqueous layer was extracted with EtOAc (2X). The combined organic layers were washed with water (1X) and then saturated aqueous sodium chloride (1X), dried over Na₂SO₄, filtered and the filtrate was concentrated to afford a yellow oil. Purification of the residue by chromatography on silica (Biotage® Snap™ column; Biotage, LLC, Charlotte, NC), 5% acetone / 5% EtOAc / 90% hexanes grading to 5% acetone / 29% EtOAc /66% hexanes) provided the title compound as a white solid.

Step D. 2-((3R,5R,6S)-5-(3-Chlorophenyl)-6-(4-chlorophenyl)-3-methyl-2-oxo-1-((S)-2-oxopentan-3-yl)piperidin-3-yl)acetic acid

Ruthenium(III) chloride hydrate (1.404 g, 6.23 mmol) was added to a solution of (3S,5R,6S)-3-allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-1-((3S)-2-hydroxypentan-3-yl)-3-methylpiperidin-2-one (Reference Example 7, Step C) (130.30 g, 283 mmol) and NaIO₄ (61.5 g) in EtOAc (630 mL), CH₃CN (630 mL) and water (935 mL) at 18 °C. The remaining NaIO₄ (307.5 g) was added in five portions over 2.5 hours while maintaining the temperature below 26°C. 15 minutes after the final addition of NaIO₄ the cooling bath was removed and the reaction mixture was stirred at ambient temperature for 50 minutes. The tan reaction mixture was filtered using a Büchner funnel and washed with EtOAc (500 mL) and CH₃CN (500 mL). The layers were separated and the aqueous layer was extracted with EtOAc twice. The organics were pooled, washed with 10% aq. NaHSO₃ (3 x 1L), brine (1 L), dried (Na₂SO₄), decanted and concentrated in vacuo to provide a green oil. The material was dissolved in a minimum amount of DCM and purified using two 1.5 kg Biotage® Snap™ columns (Biotage, LLC, Charlotte, NC) and eluting with 10-50% (15% MeOH/acetone)/hexanes to provide a light pink foam (109.67 g). ¹H NMR (400 MHz, CHLOROFORM-d) δppm 7.25 (2 H, d, J = 8.2 Hz), 6.93 - 7.18 (5 H, m), 6.73 - 6.80 (1 H, m), 4.47 (1 H, d, J = 10.6 Hz), 3.28 (1 H, ddd, J = 13.4, 10.5, 3.0 Hz), 3.16 (1 H, dd, J = 7.0, 5.5 Hz), 2.73 - 3.00 (2 H, m), 2.28 - 2.40 (1 H, m), 2.18 - 2.25 (1 H, m), 2.16 (3 H, s), 2.11 - 2.15 (1 H, m), 1.83 (1 H, ddd, J = 14.3, 7.8, 5.7 Hz), 1.47 (3 H, s), 0.64 (3 H, t, J = 7.5 Hz); MS (ESI) 476.2 [M+H]⁺.

REFERENCE EXAMPLE 8 2-((3R,5R,6S)-5-(3-Chlorophenyl)-6-(4-chlorophenyl)-1-((2S,3S)-2-hydroxypentan-3-yl)-3-methyl-2-oxopiperidin-3-yl)acetic acid

To a solution of 3.86 g (8.13 mmol) of 2-((3R,5R,6S)-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methyl-2-oxo-1-((S)-2-oxopentan-3-yl)piperidin-3-yl)acetic acid (Reference Example 7) in THF (102 mL) was added a 1 M solution of sodium tri-sec-butylborohydride (N-Selectride®, Aldrich, St. Louis, MO) in THF (16.26 mL, 16.26 mmol) at -78 °C dropwise over a period of 5 min. After being stirred at -78 °C for 30 min, the reaction was allowed to warm to rt. The reaction was stirred at rt for 2 h, the recation was quenched (sat. NH₄Cl solution), extracted (3 × EtOAc) and washed (3 × ice-cold 1 N aq. HCl and 3 × saturated aqueous sodium chloride). The combined organic layers were dried over Na₂SO₄, filtered and the filtrate was concentrated under reduced pressure. The crude material was purified by chromatography on a Biotage Isolera flash purification system (Biotage, Charlotte, NC) (2 x 1500 g columns, using a gradient from 10-30% (15% MeOH/acetone) in hexanes. The purified material was then recrystallized from 3:1 hexane/acetone (8 mL/g) to provide the title compound. ¹H NMR (500 MHz, DMSO-d₆ ) δ ppm 0.30 (t, J = 7.6 Hz, 3 H), 1.00 (d, J = 6.3 Hz, 3 H), 1.26 (s, 3 H), 1.41-1.49 (m, 1 H), 1.55-1.64 (m, 1 H), 2.04-2.15 (m, 2 H), 2.29-2.33 (m, 1 H), 2.48 (d, J = 13.7 Hz, 1 H), 2.87 (d, J = 13.7 Hz, 1 H), 3.35-3.40 (m, 1 H), 4.01-4.06 (m, 1 H), 4.77 (d, J = 10.9 Hz, 1 H), 4.80 (br. s, 1 H), 6.93-6.95 (m, 1 H), 7.08-7.10 (m, 1 H), 7.17-7.27 (m, 4 H), 7.33 (d, J = 8.4 Hz, 2 H), 12.42 (br s, 1 H); MS (ESI) 478.2 [M+H]⁺, 476.2 [M-H]^-. [α]_D = + 110° (T = 23 °C, MeOH, c = 0.51).

Alternatively the title compound can be prepared from (3S,5R,6R)-3-allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methyltetrahydro-2H-pyran-2-one as prepared in Reference Example 15 step F.

To a 10 mL round-bottom reaction flask was added (3S,5R,6R)-3-allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methyltetrahydro-2H-pyran-2-one (750 mg, 1.998 mmol), (2S,3S)-3-aminopentan-2-ol hydrochloride (837 mg, 6.00 mmol, reference: J. Org Chem., 2003, 68 (26), 9948), and triethylamine (1966 µl, 13.99 mmol). The vessel was fitted with a reflux condensor and heated to 85 to 95°C for 2d. The reaction was cooled to RT and diluted with ethyl acetate and washed with IN HCl (2 X 20 mL) and brine. The organic layer was dried over MgSO₄, filtered, and concentrated. Purification by column chromatography using 40 to 50% ethyl acetate in hexanes afforded (S)-2-((2R,3R)-2-(3-chlorophenyl)-3-(4-chlorophenyl)-3-hydroxypropyl)-N-((2S,3S)-2-hydroxypentan-3-yl)-2-methylpent-4-enamide. ¹H NMR (500 MHz, DMSO-d6) δ 7.17 (m, 2H), 7.16 (m, 1H), 7.14-7.08 (series of m, 2H), 6.97 (m, 2H), 6.88 (br d, J = 6.9 Hz, 1H), 5.96 (d, J = 8.3 Hz, 1H), 5.65 (ddt, J = 17.4, 10.2, 7.2 Hz, 1H), 5.07 (dd J = 10.3, 1.0 Hz, 1H), 5.02 (d, J = 17.6, 1H), 4.75 (t, J = 4.2 Hz, 1H), 3.79 (m, 1H), 3.66 (ddd, J = 8.8, 5.9, 4.2 Hz, 1H), 3.30 (d, J = 3.4 Hz, 1H), 3.03 (dt, J = 6.9, 5.4 Hz, 1H), 2.37 (dd, J = 13.9, 7.3 Hz, 1H), 2.32 (dd, J = 14.7, 5.6 Hz, 1H), 2.12 (dd, J = 13.7, 7.1 Hz, 1H), 2.01 (d, J = 4.7 Hz, 1H), 1.83 (dd, J = 14.7, 7.3 Hz, 1H), 1.58 (m, 1H), 1.42 (ddq, J = 14.9, 8.6, 7.3 Hz), 1.14 (s, 3H), 1.14 (d, J = 6.4 Hz, 3H), 0.90 (t, J = 7.3 Hz, 3H) ppm. LC/MS (M+H) = 478.2.

To a solution of (S)-2-((2R,3R)-2-(3-chlorophenyl)-3-(4-chlorophenyl)-3-hydroxypropyl)-N-((2S,3S)-2-hydroxypentan-3-yl)-2-methylpent-4-enamide (127 mg, 0.265 mmol) in toluene (5309 µl) was added ammonium molybdate ((NH₄)₂MoO₄) (5.20 mg, 0.027 mmol) and heated to reflux under Dean-Stark conditions overnight. The reaction was cooled to room temperature, diluted with ethyl acetate and washed with sat. NaHCO₃ and brine. The organics were dried over MgSO₄, filtered and concentrated. Purification by column chromatography using 20 to 40% ethyl acetate in hexanes afforded (1R,2R,4S)-2-(3-chlorophenyl)-1-(4-chlorophenyl)-4-((4S,5S)-4-ethyl-5-methyl-4,5-dihydrooxazol-2-yl)-4-methylhept-6-en-1-ol. ¹H NMR (500 MHz, DMSO-d6) δ 7.25 (m, 2H), 7.12 (m, 2H), 7.07 (br s, 1H), 7.05 (m, 2H), 6.96 (br d, J = 6.8 Hz, 1H), 5.53 (ddt, J = 17.4, 10.3, 7.4 Hz, 1H), 5.42 (d, J = 4.2 Hz, 1H), 4.95 (m, 2H), 4.66 (t, J = 4.9 Hz, 1H), 3.56 (dq, J = 7.6, 6.1 Hz, 1H), 3.12 (q, J = 7.1 Hz, 1H), 2.90 (ddd, (9.5, 5.1, 2.3 Hz, 1H), 2.20 (m, 2H), 1.93 (dd, J = 13.7, 7.8 Hz, 1H), 1.75 (dd, J = 14.3, 2.2 Hz, 1H), 1.11 (m, 1H), 1.10 (d, J = 6.4 Hz, 3H), 0.98 (m, 1H), 0.97 (s, 3H), 0.75 (t, J = 7.6 Hz, 3H) ppm. LC/MS (M+H) = 460.2.

To a solution of (1R,2R,4S)-2-(3-chlorophenyl)-1-(4-chlorophenyl)-4-((4S,5S)-4-ethyl-5-methyl-4,5-dihydrooxazol-2-yl)-4-methylhept-6-en-1-ol (80 mg, 0.174 mmol) in CH₂Cl₂ (1737 µ1) at -50°C was added 2,6-lutidine (46.4 µl, 0.400 mmol) followed by trifluoromethanesulfonic anhydride solution, 1 M in methylene chloride (191 µl, 0.191 mmol). The reaction was stirred at -50°C for 30 min and then treated with an additional 25 uL of trifluoromethanesulfonic anhydride solution, 1 M in methylene chloride, then 2 mL of sat. CuSO₄. The reaction was warmed to rt and extracted with dichloromethane. The organic phase was dried over MgSO₄, filtered and concentrated. Purification by column chromatography using 40 to 80% acetone in hexanes afforded (2S,3S,5S,6R,8S)-8-allyl-6-(3-chlorophenyl)-5-(4-chlorophenyl)-3-ethyl-2,8-dimethyl-2,3,5,6,7,8-hexahydrooxazolo[3,2-a]pyridin-4-ium triflate. ¹H NMR (500 MHz, DMSO-d6) δ 7.55-7.05 (series of m, 8H), 5.88 (ddt, J = 17.3, 10.0, 7.8 Hz, 1H), 5.36 (dd, J = 17.1, 2.0 Hz, 1H), 5.31 (d, J = 10.8 Hz, 1H), 5.28 (dd, J = 10.0, 2.0 Hz, 1H), 5.18 (quintet, J = 6.1 Hz, 1H), 4.10 (td, J = 6.6, 2.7 Hz, 1H), 3.98 (ddd, J = 13.7, 11.2, 3.4 Hz, 1H), 2.80 (ABX, J_AB = 13.7 Hz, J_AX = 7.3 Hz, 1H), 2.73 (ABX J_AB = 13.7 Hz, J_BX = 7.8 Hz, 1H), 2.49 (m, 1H), 2.41 (t, J = 13.7 Hz, 1H), 2.00 (dd, J = 13.9, 3.7 Hz, 1H), 1.55 (d, J = 6.1 Hz, 1H), 1.31 (s, 3H), 0.95 (dqd, J = 14.2, 7.8, 3.0 Hz, 1H), 0.58 (t, J = 7.3 Hz, 1H), 0.47 (ddq, J = 13.7, 6.3, 6.3 Hz, 1H) ppm. LC/MS (M+ = 442.2).

To a solution of (2S,3S,5S,6R,8S)-8-allyl-6-(3-chlorophenyl)-5-(4-chlorophenyl)-3-ethyl-2,8-dimethyl-2,3,5,6,7,8-hexahydrooxazolo[3,2-a]pyridin-4-ium triflate (60 mg, 0.101 mmol) in 1 mL dichloromethane at 0°C was added tetra-n-butylammonium chloride (2.81 mg, 10.13 µmol) and acetic acid (116 µl, 2.025 mmol). To this was added KMnO₄ (32.0 mg, 0.203 mmol) in 1 mL water followed by a 1 mL water rinse. An additional 10 eq. acetic acid were added followed by an additional 16 mg KMnO₄ in 1 mL water. This was repeated once more. A total of 4 eq KMnO₄ and 40 eq. acetic acid were added.

The reaction was quenched with 1 mL of sat. Na₂S₂O₃ solution and diluted with ethyl acetate. The layers were separated and the organic phase was washed once with brine, dried over MgSO₄, filtered and concentrated to afford crude (2S,3S,5S,6R,7aR)-6-(3-chlorophenyl)-5-(4-chlorophenyl)-3-ethyl-2,7a-dimethylhexahydrofuro[2,3-b]oxazolo[3,2-a]pyridin-9(5H)-one. This crude residue was redissolved in 2 mL isopropyl acetate and treated with 2 mL sat. NaHCO₃ and heated to 70°C. After 2h, the reaction was cooled to 0°C and treated with 10% acetic acid to a pH of about 3. The reaction was diluted with ethyl acetate and washed once with 10% acetic acid solution, dried over MgSO₄, filtered, and concentrated. Purification by column chromatography using 10 to 50% of (15% MeOH/acetone) in hexanes afforded 2-((3R,5R,6S)-5-(3-chlorophenyl)-6-(4-chlorophenyl)-1-((2S,3S)-2-hydroxypentan-3-yl)-3-methyl-2-oxopiperidin-3-yl)acetic acid.

REFERENCE EXAMPLE 9 2-((3R,5R,6S)-5-(3-Chlorophenyl)-6-(4-chlorophenyl)-1-((S)-1-hydroxybutan-2-yl)-3-methyl-2-oxopiperidin-3-yl)acetic acid

Step A. (S)-Methyl 2-((2S,3R)-3-(3-chlorophenyl)-2-(4-chlorophenyl)-6-oxopiperidm-1-yl)butanoate

To a 50 °C solution of 33.8 g (60 % in mineral oil, 845 mmol) of sodium hydride in 2-methyltetrahydrofuran (550 mL) was added a solution of 240 g (750 mmol) of (5R,6S)-5-(3-chlorophenyl)-6-(4-chlorophenyl)piperidin-2-one (Reference Example 1, Step E) in 2-methyltetrahydrofuran (550 mL) over a period of 45 min. After an additional 1.25 h at 50 °C, 105 mL (912 mmol) of methyl 2-bromobutyrate was added over a 20 min period. The resulting slurry was stirred at 50 °C for 3.5 h, and then was cooled to room temperature and quenched with saturated aq. NH₄Cl solution. Water was added to dissolve the precipitate and the resulting mixture was extracted with ethyl acetate (4X). The combined organic layers were washed with sat. aq. NaCl solution (1X), dried over Na₂SO₄, filtered and the filtrate was concentrated. Purification of the residue by chromatography on silica gel (Biotage® Snap™ column (Biotage, LLC, Charlotte, NC), 0 to 35% EtOAc/DCM, gradient elution) provided the title compound as a white oily solid.

Step B. (5R,6S)-5-(3-chlorophenyl)-6-(4-chlorophenyl)-1-((S)-1-hydroxybutan-2-yl)piperidin-2-one

To an ice-cooled solution of 48.5 g (115 mmol) of (S)-methyl 2-((2S,3R)-3-(3-chlorophenyl)-2-(4-chlorophenyl)-6-oxopiperidin-1-yl)butanoate (Reference Example 9, Step A) in ethyl ether (850 mL) was added 5.96 g (90%, 246 mmol) of lithium borohydride. The resulting light yellow solution was stirred at 0 °C for 3 h, and then MeOH (2.5 mL) and more ethyl ether (100 mL) were added. Gas evolution was observed upon the addition of MeOH. After 40 min, the reaction was quenched by cautious addition of 1 N HCl until bubbling subsided. The mixture was extracted with EtOAc (2X), and the combined organic layers were washed with saturated aqueous sodium chloride (1X). The organic layer was dried over Na₂SO₄, filtered and the filtrate was concentrated to afford the title compound as a white foam. The crude product was used directly in the next step without further purification.

Step C. (5R,6S)-1-((S)-1-(tert-butyldiphenylsilyloxy)butan-2-yl)-5-(3-chlorophenyl)-6-(4-chlorophenyl)piperidin-2-one

To a solution of 44.7 g (114 mmol) of (5R,6S)-5-(3-chlorophenyl)-6-(4-chlorophenyl)-1-((S)-1-hydroxybutan-2-yl)piperidin-2-one (Reference Example 9, Step B) and 19.4 g (285 mmol) of imidazole in DMF (350 mL) was added 39.4 mL (154 mmol) of tert-butyldiphenylsilyl chloride. The colorless solution was stirred at room temperature for 17 h. The reaction was partitioned between water and ethyl ether (3X), and then the combined organic layers were washed with saturated aqueous sodium chloride (1X), dried over Na₂SO₄, filtered and the filtrate was concentrated. Purification of the residue by chromatography on silica gel (Biotage® Snap™ column (Biotage, LLC, Charlotte, NC), 0 to 60% EtOAc/hexanes, gradient elution) provided the title compound as a white foam.

Step D. (5R,6S)-1-((S)-1-(tert-Butyldiphenylsilyloxy)butan-2-yl)-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methylpiperidin-2-one

To a -78 °C solution of 98.2 g (156 mmol) of (5R,6S)-1-((S)-1-(tert-butyldiphenylsilyloxy)butan-2-yl)-5-(3-chlorophenyl)-6-(4-chlorophenyl)piperidin-2-one (Reference Example 9, Step C) and 10.0 mL (160 mmol) of methyl iodide in dry, degassed THF (400 mL) was added 200 mL (200 mmol) of a degassed 1 M solution of lithium bis(trimethylsilyl)amide in THF slowly over 20 min. The orange solution was stirred at -78 °C for 1.5 h and then warmed to 0 °C and stirred for an additional 1.5 h. The reaction was quenched with saturated aqueous ammonium chloride, and extracted with EtOAc (3X). The combined organic layers were dried over Na₂SO₄, filtered and the filtrate was concentrated. Purification of the residue by chromatography on silica gel (Biotage® Snap™ column; Biotage, LLC, Charlotte, NC), 5-55% EtOAc/hexanes, gradient elution) provided the title compound as a light yellow foam.

Step E. (3S,5R,6S)-3-allyl-1-((S)-1-(tert-butyldiphenylsilyloxy)butan-2-yl)-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methylpiperidin-2-one

To a -78 °C solution of 37.3 mL (266 mmol) of diisopropylamine in dry, degassed THF (150 mL) was added 100 mL (250 mmol) of a degassed 2.5 M solution of n-butyllithium in hexanes slowly via cannula. The light yellow solution was stirred at -78 °C for 15 min, then was warmed to 0 °C and stirred for an additional 5 min. To the ice-cooled LDA solution was added a solution of 85.7 g (133 mmol) of (5R,6S)-1-((S)-1-(tert-butyldiphenylsilyloxy)butan-2-yl)-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methylpiperidin-2-one (Reference Example 9, Step D) in dry, degassed THF (210 mL) via cannula over a 15 min period. The dark orange solution was stirred at 0 °C for 30 min and then 34.5 mL (399 mmol) of allyl bromide was added quickly via syringe. After 20 sec, the ice bath was removed and the reaction was placed in a room temperature water bath and stirred for an additional 15 min. The reaction was quenched with saturated aq. ammonium chloride, and extracted with EtOAc (3X). The combined organic layers were dried over Na₂SO₄, filtered and the filtrate was concentrated. Purification of the residue by chromatography on silica gel (Biotage® Snap™ column; Biotage, LLC, Charlotte, NC), 6-14% EtOAc/hexanes, gradient elution) provided the title compound as a white foam.

Step F. 2-((3R,5R,6S)-1-((S)-1-(tert-butyldiphenylsilyloxy)butan-2-yl)-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methyl-2-oxopiperidin-3-yl)acetic acid

The title compound was prepared from (3S,5R,6S)-3-allyl-1-((S)-1-(tert-butyldiphenylsilyloxy)butan-2-yl)-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methylpiperidin-2-one (Reference Example 9, Step E) by a procedure similar to the one described in Reference Example 3, Step F. ¹H NMR (400 MHz, CHLOROFORM-d) δ ppm 0.30 (t, J=7.53 Hz, 3 H) 1.17 (s, 9 H) 1.34 - 1.48 (m, 1 H) 1.53 (s, 3 H) 1.74 - 1.88 (m, 1 H) 1.93 - 2.03 (m, 1 H) 2.29 (t, J=13.69 Hz, 1H) 2.69 (d, J=15.85 Hz, 1 H) 2.81 - 2.93 (m, 1 H) 2.98 - 3.08 (m, 1 H) 3.12 (d, J=15.65 Hz, 1 H) 3.52 (dd, J=10.66, 4.21 Hz, 1 H) 4.32 (t, J=10.27 Hz, 1 H) 4.71 (d, J=10.76 Hz, 1 H) 6.56 - 6.66 (m, 1 H) 6.91 - 6.97 (m, 1 H) 7.02 - 7.09 (m, 1 H) 7.12 - 7.18 (m, 1 H) 7.20 - 7.30 (m, 4 H) 7.33 - 7.51 (m, 6 H) 7.64 (td, J=7.83, 1.57 Hz, 4 H).

Step G. 2-((3R,5R,6S)-5-(3-chlorophenyl)-6-(4-chlorophenyl)-1-((S)-1-hydroxybutan-2-yl)-3-methyl-2-oxopiperidin-3-yl)acetic acid

To an ice-cooled solution of 370g (0.53 mmol) of 2-((3R,5R,6S)-1-((S)-1-(tert-butyldiphenylsilyloxy)butan-2-yl)-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methyl-2-oxopiperidin-3-yl)acetic acid (Reference Example 9, Step F) in THF (15 mL) was added 2.60 mL (2.60 mmol) of a 1 M solution of TBAF in THF. The yellow solution was warmed to rt and stirred for 5 h. At this time 2.60 mL (2.60 mmol) of a 1 M solution of TBAF in THF was added and the reaction was stirred for an additional 20 h. The reaction was partitioned between 1 N HCl and EtOAc (4X). The combined organic layers were dried over Na₂SO₄, filtered and the filtrate was concentrated. The residue was purified by reverse phase prep. HPLC (Sunfire™ Prep C₁₈ OBD 10 µm column (Waters, Milford, MA), gradient elution of 40% MeCN in water to 80% MeCN in water over a 30 min period, where both solvents contain 0.1% TFA) provided the title compound as a white solid. ¹H NMR (400 MHz, CDCl₃) δ ppm 7.23-7.28 (2 H, m), 7.15-7.20 (1 H, m), 7.07-7.14 (1 H, m), 6.98-7.06 (3 H, m), 6.74 (1 H, d, J = 7.1 Hz), 4.55 (1 H, dd J = 9.8 Hz, 2.9 Hz), 3.71-3.79 (1 H, m), 3.58-3.66 (1 H, m), 3.19-3.28 (1 H, m), 3.07-3.16 (1 H, m), 2.96-3.03 (1 H, m), 2.75 (1 H, dd, J = 14.9 Hz, 2.9 Hz), 2.16-2.25 (1 H, m), 2.03-2.10 (1 H, m), 1.87-1.98 (1 H, m), 1.46 (3 H, s), 1.41-1.54 (m, 1 H), 0.63 (3 H, dd, J = 7.3 Hz, 3.3 Hz). Mass Spectrum (ESI) m/z = 464.1 (M+1).

REFERENCE EXAMPLE 10 2-((3R,5R,6S)-1-((S)-2-(tert-Butoxy)-1-cyclopropyl-2-oxoethyl)-5-(3-chlorophenyl)-6-(4-chlorophenyl)-2-oxopiperidin-3-yl)acetic acid

Step A. Ethyl 2-bromo-2-cyclopropylacetate.

To a solution of 2-cyclopropylacetic acid (24.7 g, 247 mmol) in anhydrous DCE (250 mL) was added thionyl chloride (22 mL, 302 mmol) dropwise for 5 minutes at 25 °C. After being refluxed for 2 h, the reaction was cooled to room temperature, N-bromosuccinimde (53.6 g, 301 mmol) and hydrogen bromide (48% aqueous solution) (0.195 mL, 1.727 mmol) were added successively at 25 °C. The resulted mixture was heated to refux for 96h. After the reaction mixture was cooled to room temperature, absolute EtOH (200 mL) was added and the resulting dark brown solution was stirred at room temperature for an hour. The reaction mixture was concentrated under reduced pressure (35 °C, 4.0 kilopascal) and the residue was suspended in carbon tetrachloride (300 mL) and passed through a glass filter. The filtrate was concentrated under reduced pressure (35 °C, 4.0 kilopascal). Purification of the crude product by chromatography (silica gel, 330 g × 2, 5 % ethyl acetate/hexane) and concentration of the desired combined fractions under reduced pressure (35 °C, 4.0 kilopascal) provided the title compound as a pale yellow liquid. ¹H NMR (400 MHz, CHLOROFORM-d) δ ppm 4.20 - 4.32 (2 H, m), 3.59 (1 H, d, J=10.4 Hz), 1.53 - 1.66 (1 H, m), 1.29 - 1.36 (3 H, m), 0.76 - 0.93 (2 H, m), 0.51 - 0.61 (1 H, m), 0.40 - 0.47 (1 H, m).

Step B. (S)-Ethyl 2-((2S, 3R)-3-(3-chlorophenyl)-2-(4-chlorophenyl)-6-oxopiperidin-1-yl)-2-cyclopropylacetate

To a solution of (3S,5R,6S)-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-piperidin-2-one (8.01g, 25 mmol; Reference Example 1, Step E) in DMF (60 mL) was added 60% sodium hydride in mineral oil (2.0 g, 50 mmol) at 0 °C and the mixture thus obtained was stirred at same temperature for 30 min. To the mixture was added ethyl 2-bromo-2-cyclopropylacetate (12.18 g, 50 mmol) in DMF (10 mL) dropwise and the mixture was stirred at room temperature 2 h, then the reaction was quenched with sat. ammonium chloride solution and diluted with ethyl acetate. The organic layer was washed with 10% aq. citric acid, 5% aq. NaHCO₃ solution, water, sat. aq. NaCl solution, then dried over MgSO₄. The solvent was evaporated under reduced pressure and the residue was purified by chromatography on silica gel eluting with 20% to 50% ethyl acetate in hexane to give the title compound as the first eluting diastereomer, a white solid. ¹H NMR (400 MHz, CHLOROFORM-d) δ ppm -0.34 (m, 1H), 0.23 (m, 1H), 0.38 (m, 1H), 0.62 (m, 1H), 1.26 (t, J=8 Hz, 3H), 1.39 (m, 1H), 2.13 (m, 2H), 2.63 (m, 2H), 3.09 (m, 1H), 3.20 (d, J=12 Hz, 1H), 4.07 (m, 2H), 4.81 (d, J=8 Hz, 1H), 6.90 (dt, J=7.1, 1.7 Hz, 1H), 7.11-7.19 (m, 5H), 7.28 (m, 2H). Mass Spectrum (ESI) m/z = 446.2 (M+1).

Step C. (S)-tert-Butyl 2-((2S,3R)-3-(3-chlorophenyl)-2-(4chlorophenyl)-6-oxopiperidin-1-yl)-2-cyclopropylacetate

To a solution of (S)-ethyl 2-((2S,3R)-3-(3-chlorophenyl)-2-(4-chlorophenyl)-6-oxopiperidin-l-yl)-2-cyclopropylacetate (500 mg, 1.12 mmol) (Reference Example 10, Step B) in THF/MeOH/H₂O (5/5/5, 15 mL) was added lithium hydroxide (1.68 mL, 3.36 mmol) at rt, and then the reaction was heated to 60 °C. After being stirred at 60 °C for 1.5 h, the reaction was quenched with saturated aqueous NH₄Cl solution and extracted (2 × DCM). The combined organic layers were washed (1 × sat. aq. NaCl solution), dried over Na₂SO₄, filtered and the filtrate was concentrated and concentrated under reduced pressure.

The crude acid (450 mg, 1.076 mmol) synthesized above was dissolved in DCM (10 mL) and sulfuric acid (115 uL, 2.151 mmol) was added, followed by 2-methy1prop-1-ene (1.207 g, 21.51 mmol) at -78 °C. The reaction vessel was sealed and the mixture was slowly warmed to ambient temperature. After being vigorously stirred for 4 days, the reaction was quenched with sat. aqueous NH₄Cl solution and extracted with ethyl acetate. The combined organic layers were washed with sat. aq. NaCl solution and dried over sodium sulfate, filtered and the filtrate was concentrated under reduced pressure. Purification of the residue by flash chromatography on silica gel (eluent: 40% EtOAc/hexanes) provided the title compound.

Step D. (S)-tert-Butyl 2-((3S,5R,6S)-3-allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-2-oxopiperidin-1-yl)-2-cyclopropylacetate

A solution of lithium bis(trimethylsilyl)amide (1M in THF, 0.165 mL, 0.165 mmol) was added dropwise at -78 °C to a solution of of (S)-tert-butyl 2-((2S,3R)-3-(3-chlorophenyl)-2-(4chlorophenyl)-6-oxopiperidin-1-yl)-2-cyclopropylacetate (Reference Example 10, Step C, 71 mg, 0.15 mmol) and allyl bromide (15.54 uL, 0.165 mmol) in 0.5 mL of THF . The reaction was allowed to warm to ambient temperature. After stirring for 2 h, the reaction was quenched with sat. aqueous ammonium chloride solution and extracted with ethyl acetate. The combined organic layers were washed with sat. aq. NaCl solution and dried over sodium sulfate, then filtered and the filtrate was concentrated under reduced pressure. Purification by flash chromatography on silica gel eluting with ethyl acetate/hexane provided the title compound.

Step E. 2-((3R,5R,6S)-5-(3-Chlorophenyl)-6-(4-chlorophenyl)-1-((S)-1-(N-cyclopropylacetamido)butan-2-yl)-3-methyl-2-oxopiperidin-3-yl)acetic acid

The title compound was obtained from (S)-tert-butyl 2-((3S,5R,6S)-3-allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-2-oxopiperidin-1-yl)-2-cyclopropylacetate (Reference Example 10, Step D) by the procedure of reference example 3, step F. ¹H NMR (400 MHz, CHLOROFORM-d) δ ppm 0.08 (m, 1 H), 0.49 (m, 1 H), 0.58 (m, 1 H), 0.66 (m, 1 H), 1.02 (m, 1 H), 1.44 (s, 9 H), 1.99 (m, 1 H), 2.19 (m, 1 H), 2.58 (dd, J = 16.0, 4.0 Hz,1 H), 2.66 (m, 1 H), 2.93 (dd, J = 12.0, 12.0 HZ, 1 H), 3.20 (s, 1 H), 3.34 (d, J=12 HZ, 1 H), 5.37 (s, 1 H), 7.14 (m, 1 H), 7.25-7.33 (m, 3 H), 7.37-7.45 (m, 4 H). Mass Spectrum (ESI) m/z = 532.2 (M+1).

REFERENCE EXAMPLE 11 2-((3R,5R,6S)-5-(3-chlorophenyl)-6-(4-chlorophenyl)-1-((S)-1-cyclopropyl-2-hydroxyethyl)-3-methyl-2-oxopiperidin-3-yl)acetic acid

Step A. (5R,6S)-5-(3-chlorophenyl)-6-(4-chlorophenyl)-1-((S)-1-cyclopropyl-2-hydroxyethyl)piperidin-2-one

A solution of lithium borohydride (2M in THF, 15.46 mL, 30.9 mmol) was added to a solution at 0°C of (S)-ethyl 2-((2S,3R)-3-(3-chlorophenyl)-2-(4-chlorophenyl)-6-oxopiperidin-1-yl)-2-cyclopropylacetate (Reference Example 10, Step B, 2.3g, 5.15 mmol) in ether (40 mL). After stirring at ambient temperature for 20 hours, the reaction was quenched with saturated aq. NH₄Cl solution and extracted into EtOAc. The organic layer was washed with sat. aq. NaCl solution, dried over sodium sulfate and concentrated to give the title compound as a solid, which was used without further purification. ¹H NMR (400 MHz, CHLOROFORM-d) δ ppm 0.00 (m, 1H), 0.23 (m, 1H), 0.48-0.57 (m, 2H), 0.85 (m, 1H), 1.99 (m, 1H), 2.07 (m, 1H), 2.61 (m, 2H), 2.64 (m, 1H), 3.22 (dd, J=11.2, 9.8 Hz, 1H), 3.42 (td, J=10.1, 4.3 Hz, 1H), 3.60 (m, 1H), 4.93 (d, J=6.5 Hz, 1H), 6.89 (m, 1H), 7.09 (m, 4H), 7.18 (m, 2H), 7.27 (m, 1H). Mass Spectrum (ESI) m/z = 404.0 (M+1).

Step B. (SR,6S)-1-((S)-2-((tert-Butyldiphenylsilyl)oxy)-1-cyclopropylethyl)-5-(3-chlorophenyl)-6-(4-chlorophenyl)piperidin-2-one

The product of reference example 11 step A was converted to the title compound by a procedure similar to the one described in reference example 9 step C. ¹H NMR (400 MHz, CHLOROFORM-d) δ ppm -0.70 (m, 1H), -0.40 (m, 1H), 0.02 (m, 1H), 0.13 (m, 1H), 0.91 (s, 9H), 1.09 (m, 1H), 1.92-1.91 (m, 2H), 2.47-2.50 (m, 2H), 2.78 (s, br, 1H), 2.80 (m, 1H), 3.31 (m, 1H), 3.98 (m, 1H), 4.62 (d, J=7.8 Hz, 1H), 6.60 (m, 1H), 6.82-6.91 (m, 4H), 6.91-7.03 (m, 3H), 7.18-7.26 (6H), 7.37-7.45 (m, 4H). Mass Spectrum (ESI) m/z = 642.3 (M+1).

Step C. (SR,6S)-1-((S)-2-((tert-Butyldiphenylsilyl)oxy)-1-cyclopropylethyl)-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methylpiperidin-2-one

(5R,6S)-1-((S)-2-((tert-butyldiphenylsilyl)oxy)-1-cyclopropylethyl)-5-(3-chlorophenyl)-6-(4-chlorophenyl)piperidin-2-one (Reference Example 11 Step B, 7.9g, 12.29 mmol) was converted to the title compound, mixture of diastereomers by the method of Reference Example 9, Step D. ¹H NMR (400 MHz, CHLOROFORM-d) δ ppm -0.15 (m, 1H), 0.00 (m,1H), 0.41-0.52 (m, 2H), 1.26 (s, 9H), 1.41 (m, 1H), 1.62 (d, J=7.2 Hz, 3H), 2.09 (m, 1H), 2.30 (m, 1H), 2.87 (m, 1H), 3.28 (m, 2H), 3.68 (m, 1H), 4.23 (m, 1H), 5.11 (d, J=6.1 Hz, 1H), 7.16-7.34 (m, 4H), 7.37-7.46 (m, 4H), 7.51-7.65 (m, 6H), 7.74-7.78 (m, 4H).

Step D. (SR,6S)-3-Allyl-1-((S)-2-((tert-butyldiphenylsilyl)oxy)-1-cyclopropylethyl)-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methylpiperidin-2-one

(5R,6S)-1-((S)-2-(tert-Butyldiphenylsilyloxy)-1-cyclopropylethyl)-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methylpiperidin-2-one (5.02 g, 7.64 mmol, Reference Example 11, Step C) was converted into the title compound by the procedure described for Reference Example 9, Step E. After workup, the unpurified product was used as obtained.

Step E. 2-((3R,5R,6S)-1-((S)-2-((tert-Butyldiphenylsilyl)oxy)-1-cyclopropylethyl)-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methyl-2-oxopiperidin-3-yl)acetic acid

(5R,6S)-3-allyl-1-((S)-2-((tert-Butyldiphenylsilyl)oxy)-1-cyclopropylethyl)-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methylpiperidin-2-one (Reference Example 11, Step D, 106 mg, 0.15 mmol) was treated according to the procedure of Reference Example 9, Step F to provide 2-((3R,SR,6S)-1-((S)-2-((tert-butyldiphenylsilyl)oxy)-1-cyclopropylethyl)-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methyl-2-oxopiperidin-3-yl)acetic acid. Mass Spectrum (ESI) m/z = 714.3 (M+1).

Step F. 2-((3R,5R,6S)-5-(3-chlorophenyl)-6-(4-chlorophenyl)-1-((S)-1-cyclopropyl-2-hydroxyethyl)-3 -methyl-2-oxopiperidin-3 -yl)acetic acid

A solution of tetrabutylammonium fluoride, (1.0 M in THF, 0.453 mL, 0.453 mmol) was added to a solution of 2-((3R,5R,6S)-1-((S)-2-(tert-butyldiphenylsilyloxy)-1-cyclopropylethyl)-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methyl-2-oxopiperidin-3-yl)acetic acid (Reference Example 11, Step E, 108mg, 0.151 mmol) in THF (4ml) and the reaction was stirred at ambient temperature for 20 hours. Analysis by LC-MS showed incomplete reaction so an extra 0.225ml of tetrabutylammonium fluoride solution was added and the reaction was stirred for another 26 hours. The mixture was diluted in ethyl acetate then washed with water and sat. aq. NaCl solution. The organic layer was dried over sodium sulfate and concentrated. Purification by RP-HPLC (Sunfire Prep C₁₈ OBD 10 µm column, gradient elution of 10% MeCN in water to 80% MeCN in water over a 30 min period, where both solvents contain 0.1% TFA) afforded the title compound as a solid. ¹H NMR (400 MHz, CHLOROFORM-d) δppm -0.30 (s, m, 1H), 0.00 (s, m, 1H), 0.37 (m, 2H), 0.79 (m, 1H), 1.22 (s, 3H), 2.00 (m, 2H), 2.52 (d, J=14.1 Hz, 1H), 2.70 (d, J=13.9 Hz, 1H), 3.00 (m, 2H), 3.20 (s, br, 3H), 3.29 (m, 1H), 4.65 (d, J=10.o Hz, 1H), 6.61 (m, 1H), 6.84 (s, br, 2H), 6.97 (m, 3H), 7.04 (m, 2H). Mass Spectrum (ESI) m/z = 476.2 (M+1).

REFERENCE EXAMPLE 12 2-((3R,5R,6S)-5-(3-Chlorophenyl)-6-(4-chlorophenyl)-1-((1S,2S)-1-cyclopropyl-2-hydroxybutyl)-3-methyl-2-oxopiperidin-3-yl)acetic acid or 2-((3R,5R,6S)-5-(3-Chlorophenyl)-6-(4-chlorophenyl)-1-((1S,2R)-1-cyclopropyl-2-hydroxybutyl)-3-methyl-2-oxopiperidin-3-yl)acetic acid

Step A. (3S,5R,6S)-3-Allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-1-((S)-1-cyclopropyl-2-hydroxyethyl)-3-methylpiperidin-2-one

A solution of tetrabutylammonium fluoride in THF (1M, 2.10 mL, 2.10 mmol) was added to a solution of diastereomers (5R,6S)-3-allyl-1-((S)-2-(tert-butyldiphenylsilyloxy)-1-cyclopropylethyl)-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methylpiperidin-2-one (Reference Example 11, Step D, 488mg, 0.700 mmol) in THF (10ml).The reaction was stirred at ambient temperature for 2 hours. The mixture was diluted in ethyl acetate and washed with water and sat. aq. NaCl solution. The organic layer was dried over sodium sulfate. Silica gel chromatography eluting with ethyl acetate/hexane gave the title compound as a single diastereomer. Mass Spectrum (ESI) m/z = 458.0 (M+1)

Step B. (S)-2-((3S,5R,6S)-3-Allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methyl-2-oxopiperidin-1-yl)-2-cyclopropylacetaldehyde

(3S,5R,6S)-3-Allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-1-((S)-1-cyclopropyl-2-hydroxyethyl)-3-methylpiperidin-2-one (Reference Example 12, Step A, 80 mg, 0.17 mmol) was converted to the title compound as a white foam by the procedure described in Reference Example 4, Step C. Mass Spectrum (ESI) m/z = 456.1 (M+1)

Step C. (3S,5R,6S)-3-Allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-1-((1S,2S)-1-cyclopropyl-2-hydroxybutyl)-3-methylpiperidin-2-one or (3S,5R,6S)-3-Allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-1-((1S,2R)-1-cyclopropyl-2-hydroxybutyl)-3-methylpiperidin-2-one

By the procedure of Reference Example 6, Step A, substituting ethyl magnesium bromide for methyl magnesium bromide, (S)-2-((3S,5R,6S)-3-allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methyl-2-oxopiperidin-1-yl)-2-cyclopropylacetaldehyde (Reference Example 12, Step B, 90mg, 0.20 mmol) was converted to the title compound which was obtained as the second eluting diastereomer after chromatography . ¹H NMR (400 MHz, CHLOROFORM-d) δ ppm -0.43 (m, 1H), -0.16 (m, 1H), 0.32 (m, 1H), 0.51 (m, 1H), 0.78 (t, J=.3 Hz, 3H), 1.18 (s, 3H), 1.21-1.35 (m, 1H), 2.54 (m, 2H), 1.57 (s, br, 1H), 1.87-2.0 (m, 2H), 2.21 (s, br, 1H), 2.50-2.62 (m, 2H), 3.22 (ddd, J=12.8, 10.2, 4.0 Hz, 1H), 3.68 (s, br, 1H), 4.34 (d, J=10.0 Hz, 1H), 5.12 (s, 1H), 5.14 (d, J=8 Hz, 1H), 5.79 (m, 1H), 6.65 (dt, J=7.6, 1.6 Hz, 1H), 6.87-6.91 (m, 3H), 7.01-7.07 (m, 2H), 7.16-7.18 (m, 2H). Mass Spectrum (ESI) m/z = 486.3 (M+1)

Step D. 2-((3R,5R,6S)-5-(3-Chlorophenyl)-6-(4-chlorophenyl)-1-((1S,2S)-1-cyclopropyl-2-hydroxybutyl)-3-methyl-2-oxopiperidin-3-yl)acetic acid or 2-((3R,5R,6S)-5-(3-Chlorophenyl)-6-(4-chlorophenyl)-1-((1S,2R)-1-cyclopropyl-2-hydroxybutyl)-3-methyl-2-oxopiperidin-3-yl)acetic acid

The title compound was obtained by treating the compound of Reference Example 12, Step C by the method described in Reference Example 3, Step F. ¹H NMR (400 MHz, Methanol-d4) δ ppm -0.16 (s, br, 1H), 0.26 (s, br, 1H), 0.55 (s, br, 1H), 0.67 (s, br, 1H), 0.86 (m, 3H), 1.32 (m, 4H), 1.41 (s, 3H), 1.68 (m, 1H), 1.92 (m, 2H), 2.64 (d, J=12 Hz, 1H), 2.99 (d, J=12 Hz, 1H), 3.51 (m, 1H), 4.97 (m, 1H), 6.97 (m, 1H), 7.06 (m, 1H), 7.17 (m, 4H), 7.28 (m, 2H). Mass Spectrum (ESI) m/z = 504.1 (M+1).

REFERENCE EXAMPLE 13 2-((3R,5R,6S)-5-(3-Chlorophenyl)-6-(4-chlorophenyl)-1-((1S,2R)-1-cyclopropyl-2-hydroxypropyl)-3-methyl-2-oxopiperidin-3-yl)acetic acid.

Step A. (3S,5R,6S)-3-Allyl-1-((S)-2-(tert-butyldiphenylsilyloxy)-1-cyclopropylethyl)-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methylpiperidin-2-one

The mixture of diastereomers prepared from (5R,6S)-1-((S)-2-(tert-butyldiphenylsilyloxy)-1-cyclopropylethyl)-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methylpiperidin-2-one (4.34 g, 6.61 mmol) by the method of Reference Example 11, Step D was purified by silica gel chromatography, eluting with ethyl acetate/hexanes. Fractions containing the desired epimer were combined and concentrated to give (3S,5R,6S)-3-allyl-1-((S)-2-(tert-butyldiphenylsilyloxy)-1-cyclopropylethyl)-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methylpiperidin-2-one as a white foam weighing 3.01 g (65% yield). MS (ESI) m/z = 696 [M+H]⁺.

Step B. (3S,5R,6S)-3-Allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-1-((S)-1-cyclopropyl-2-hydroxyethyl)-3-methylpiperidin-2-one. (see also Reference Example 12 step A)

Treating (3S,5R,6S)-3-allyl-1-((S)-2-(tert-butyldiphenylsilyloxy)-1-cyclopropylethyl)-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methylpiperidin-2-one (Reference Example 13 , Step A, 3.00 g, 4.31 mmol) according to the procedure of Reference Example 12, Step A gave (3S,5R,6S)-3-allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-1-((S)-1-cyclopropyl-2-hydroxyethyl)-3-methylpiperidin-2-one as a white foam (1.905 g, 97%). ¹H NMR (500 MHz, CHLOROFORM-d) δ 0.00 - 0.15 (m, 1 H), 0.18 - 0.35 (m, 1 H), 0.44 - 0.69 (m, 2 H), 0.75 - 0.87 (m, 1 H), 1.28 (s, 3 H), 1.87 - 2.03 (m, 2 H), 2.48 - 2.72 (m, 2 H), 3.01 - 3.22 (m, 2 H), 3.41 (td, J = 10.33, 4.52 Hz, 1H), 3.60 (dd, J = 11.00, 4.40 Hz, 1H), 4.86 (d, J = 10.03 Hz, 1 H), 5.06 - 5.24 (m, 2 H), 5.74 - 5.97 (m, 1 H), 6.74 (d, J = 7.58 Hz, 1H), 6.86 - 7.10 (m, 3 H), 7.10 - 7.26 (m, 4 H). MS (ESI) m/z = 458 [M+H]⁺

Step C. (S)-2-((3S,5R,6S)-3-Allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methyl-2-oxopiperidin-1-yl)-2-cyclopropylacetaldehyde. (see also Reference Example 12 step B)

(3S,5R,6S)-3-Allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-1-((S)-1-cyclopropyl-2-hydroxyethyl)-3-methylpiperidin-2-one (Reference Example 13, Step B, 1.01 g, 2.2 mmol) was converted to the title compound as a white foam (866 mg, 86%) by the procedure described in Reference Example 4, Step C. MS (ESI) m/z = 456 [M+H]⁺.

Step D. (3S,5R,6S)-3-allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-1-((1S,2R)-1-cyclopropyl-2-hydroxypropyl)-3-methylpiperidin-2-one and (3S,5R,6S)-3-allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-1-((1S,2S)-1-cyclopropyl-2-hydroxypropyl)-3-methylpiperidin-2-one

By the procedure of Reference Example 6, Step A, (S)-2-((3S,5R,6S)-3-allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methyl-2-oxopiperidin-1-yl)-2-cyclopropylacetaldehyde (Reference Example 13, Step C, 866 mg, 1.897 mmol) was treated with methyl magnesium bromide to give the diastereomeric alcohols (3S,5R,6S)-3-allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-1-((1S,2R)-1-cyclopropyl-2-hydroxypropyl)-3-methylpiperidin-2-one and (3S,5R,6S)-3-allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-1-((1S,2S)-1-cyclopropyl-2-hydroxypropyl)-3-methylpiperidin-2-one as a white foam. MS (ESI) m/z = 472 [M+H]⁺.

Step E. 2-((3R,5R,6S)-5-(3-Chlorophenyl)-6-(4-chlorophenyl)-1-((S)-1-cyclopropyl-2-oxopropyl)-3-methyl-2-oxopiperidin-3-yl)acetic acid.

(3S,5R,6S)-3-Allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-1-((S)-1-cyclopropyl-2-hydroxypropyl)-3-methylpiperidin-2-one (Reference Example 13, Step D, 809 mg, 1.71 mmol) was treated according to the procedure described in Reference Example 3, Step F, to afford, after SFC purification, 2-((3R,5R,6S)-5-(3-chlorophenyl)-6-(4-chlorophenyl)-1-((S)-1-cyclopropyl-2-oxopropyl)-3-methyl-2-oxopiperidin-3-yl)acetic acid as a white solid. ¹H NMR (500 MHz, Methanol-D4) δ -0.70 - -0.47 (m, 1 H), 0.10 (dq, J = 9.78, 5.05 Hz, 1H), 0.31 - 0.48 (m, 1 H), 0.63 (tt, J = 8.59, 5.35 Hz, 1 H), 1.34 (s, 3 H), 1.47 - 1.58 (m, 1 H), 2.15 - 2.35 (m, 6 H), 2.65 (d, J = 13.69 Hz, 1H), 2.79 (d, J = 10.03 Hz, 1 H), 2.98 (d, J = 13.69 Hz, 1 H), 3.48 - 3.57 (m, 1 H), 4.65 (d, J = 10.51 Hz, 1 H), 6.94 - 7.01 (m, 1 H), 7.08 (s, 1 H), 7.11 - 7.54 (m, 6 H). MS (ESI) m/z = 488 [M+H]⁺.

Step F. 2-((3R,5R,6S)-5-(3-Chlorophenyl)-6-(4-chlorophenyl)-1-((1S,2R)-1-cyclopropyl-2-hydroxypropyl)-3-methyl-2-oxopiperidin-3-yl)acetic acid

Reduction of 2-((3R,5R,6S)-5-(3-chlorophenyl)-6-(4-chlorophenyl)-1-((S)-1-cyclopropyl-2-oxopropyl)-3-methyl-2-oxopiperidin-3-yl)acetic acid in methanol at 0°C with sodium borohydride provided a mixture of the diastereomeric alcohols in ∼2:1 ratio. The residue was purified by silica gel chromatography eluting with a gradient of isopropanol in hexanes. Fractions containing the major isomer were concentrated and then lyophilized from acetonitrile/water to provide the title compound as a fluffy white solid. ¹H NMR (500 MHz, Methanol-d4) δ ppm -0.29 (br s,1 H), 0.20 (br s, 1 H), 0.46 (br s,1 H), 0.60 (br s,1 H), 1.19 (br s,3 H), 1.24 - 1.35 (m, 1 H), 1.39 (s, 3 H), 2.10 - 2.29 (m, 2 H), 2.63 (d, J = 13.69 Hz, 1 H), 2.82 (br s,1 H), 2.98 (d, J = 13.94 Hz, 1 H), 3.40 - 3.50 (m, 1 H), 3.57 (br s,1 H), 4.82 (d, J = 11.00 Hz, 1 H), 6.61 - 7.64 (m, 8 H). MS (ESI) m/z = 490 [M+H]⁺.

REFERENCE EXAMPLE 14 2-((3R,5R,6S)-5-(3-Chlorophenyl)-6-(4-chlorophenyl)-1-((1S,2S)-1-cyclopropyl-2-hydroxypropyl)-3-methyl-2-oxopiperidin-3-yl)acetic acid

L-Selectride® (Aldrich, St. Louis, MO), (1M in THF, 5.0 ml, 5.00 mmol) was added dropwise over the course of 5 minutes to a solution of 2-((3R,5R,6S)-5-(3-chlorophenyl)-6-(4-chlorophenyl)-1-((S)-1-cyclopropyl-2-oxopropyl)-3-methyl-2-oxopiperidin-3-yl)acetic acid (Reference Example 13, Step E, 1.035 g, 2.12 mmol) in THF (35 ml) at -78 °C. After 90 min, the mixture was allowed to warm to 0 °C and was carefully quenched by the addition of saturated ammonium chloride. The aqueous phase was extracted three times with ethyl acetate. The combined organic layer was washed with 1 M HCl, water, sat. aq. NaCl solution and dried over sodium sulfate. After concentration in vacuo, the residue was purified by silica chromatography eluting with a gradient of isopropanol in hexanes. Fractions containing the major isomer were concentrated and then lyophilized from acetonitrile/water to provide the title compound as a white powder. Stereochemistry assigned by analogy to Reference Example 8. ¹H NMR (500 MHz, DMSO-d₆) δ -0.69 (br s, 1 H), -0.35 (br s, 1 H), 0.17 (br s, 1 H), 0.36 (br s, 1 H), 1.07 (br s, 1 H), 1.27 (s, 4 H), 1.98 - 2.23 (m, 2 H), 2.53 - 2.58 (m, 1 H), 2.93 (d, J = 13.94 Hz, 1 H), 3.36 - 3.49 (m, 1 H), 3.74 - 4.44 (m, 1H), 4.46 - 5.11 (m, 2 H), 6.60 - 7.59 (m, 8 H). MS (ESI) m/z = 490 [M+H]⁺.

REFERENCE EXAMPLE 15 2-((3R,5R,6S)-5-(3-Chlorophenyl)-6-(4-chlorophenyl)-1-((2S,3S)-2-hydroxy-4-methylpentan-3-yl)-3-methyl-2-oxopiperidin-3-yl)acetic acid.

Step A: Methyl 4-(3-chlorophenyl)-5-(4-chlorophenyl)-2-methyl-5-oxopentanoate

Methyl methacrylate (82 mL, 773 mmol) was added to a solution of 2-(3-chlorophenyl)-1-(4-chlorophenyl)ethanone (195.2 g, 736 mmol; ReferenceExample 1, Step A) in anhydrous THF (1.5 L) under an atmosphere of nitrogen. A suspension of potassium t-butoxide (8.26 g, 73.6 mmol) in anhydrous THF (340 mL) (sonicated to break up the solids) was then prepared and cannulated into the solution containing the 2-(3-chlorophenyl)-1-(4-chlorophenyl)ethanone. The solution was cooled to ∼16°C and the orange colored solution was left to stir at ambient temperature for 2.5d. (After 2 d TLC shows the absence of the starting material). The mixture was concentrated under vacuum. The residual reddish brown oil was diluted with ethyl acetate (900 mL) and washed with water (4 x 190 mL) and then sat. aq. NaCl solution. The organic layer was dried over magnesium sulfate and concentrated under reduced pressure to provide the title compound as a racemic mixture of diastereomers. ¹H-NMR (500 MHz, CDCl₃) δ 7.88 (m, 4H), 7.39 (m, 2H), 7.27-7.12 (series of m, 4H), 4.62 (dd, J = 9.0, 5.6 Hz, 0.5H), 4.59 (dd, J = 9.3, 5.4 Hz, 0.5H), 3.69 (s, 1.5H), 3.60 (s, 1.5 H), 2.46 (m, 1H), 2.33 (m, 1H), 2.08 (ddd, J = 13.9, 9.3, 5.4 Hz, 0.5 H), 1.97 (ddd, J = 13.7, 9.0, 4.4 Hz, 0.5H), 1.23 (d, J = 6.9 Hz, 1.5 H), 1.16 (d, J = 7.1 Hz, 1.5H) ppm.

Step B: Racemic mixture of (4R,5R)-methyl 4-(3-chlorophenyl)-5-(4-chlorophenyl)-5-hydroxy-2-methylpentanoate (4S,5S)-methyl 4-(3-chlorophenyl)-5-(4-chlorophenyl)-5-hydroxy-2-methylpentanoate

Anhydrous methanol (600 mL) was placed in a 3L three-necked round-bottomed flask equipped with a stir bar and temperature probe under an atmosphere of N₂ and cooled to about -20°C. Sodium borohydride (26.2 g, 693 mmol) was added in 5g portions. Via an addition funnel, a solution of methyl 4-(3-chlorophenyl)-5-(4-chlorophenyl)-2-methyl-5-oxopentanoate (253 g, 693 mmol; Reference Example 15, Step A) in methanol (600 mL) was added dropwise to the reaction, maintaining a temperature between -27°C to -30°C. The reddish solution was stirred at -30°C for 30 minutes and then allowed to warm to -15°C. The reaction was monitored for completion by TLC. The reaction was quenched by slowly adding water (68.6 mL, 3.8mol) through the addition funnel. The mixture was allowed to warm to ambient temperature. Solvents were removed under vacuum. The residual yellowish oil was diluted in ethyl acetate (1.2 L) and washed with water (400 mL). The organic layer was washed with sat. aq. NaCl solution (2 x 300 mL), forming an emulsion. After waiting for the most of the emulsion to separate, the organic layer was dried over magnesium sulfate. The solution was filtered through filter paper and concentrated under vacuum to provide a racemic mixture of diastereomers. ¹H-NMR (500 MHz, DMSO-d6) δ 7.33 (m, 2H), 7.27-7.17 (series of m, 5H), 7.04 (m, 1H), 5.43 (d, J = 4.4 Hz, 0.5H), 5.37 (d, J = 4.6 Hz, 0.5H), 4.77 (t, J = 5.4 Hz, 0.5H), 4.71 (dd, J = 6.6, 4.9 Hz, 0.5H), 5.33 (s, 1.5H), 3.46 (s, 1.5 H), 2.87 (dt, J = 10.2, 4.7 Hz, 0.5H), 2.75 (ddd, J = 11.2, 6.6, 4.9 Hz, 0.5H), 2.04 (m, 1.5 H), 1.71 (m, 1H), 1.46 (m, 0.5H), 0.97 (d, J = 6.6 Hz, 1.5H), 0.94 (d, J = 7.1 Hz, 1.5H) ppm. TLC (20% EtOAc / Hexane) R_f = 0.34.

Step C. (4R,5R)-4-(3-Chlorophenyl)-5-(4-chlorophenyl)-5-hydroxy-2-methylpentanoic acid and (4S,5S)-4-(3-Chlorophenyl)-5-(4-chlorophenyl)-5-hydroxy-2-methylpentanoic acid.

A solution of the racemic mixture of (4R,5R)-methyl 4-(3-chlorophenyl)-5-(4-chlorophenyl)-5-hydroxy-2-methylpentanoate and (4S,5S)-methyl 4-(3-chlorophenyl)-5-(4-chlorophenyl)-5-hydroxy-2-methylpentanoate (245.7 g, 669 mmol; Reference Example 15, Step B) in THF (1.17 L) was prepared by warming to 40 °C. The flask was cooled to ∼14 °C, internal temperature. A solution of lithium hydroxide hydrate (42.1 g, 1.0 mol) in water (585 mL) was cautiously added to the THF solution. The mixture was left to stir at ambient temperature and monitord by LC/MS for the absence of starting material (∼2.5 h). Upon completion, the solution was again cooled to a temperature of ∼14°C. 2N HCl (526 mL) was added slowly. The layers were partitioned and the aqueous layer (pH ∼2) was washed with ethyl acetate (1 x 500 mL then 1 x 250 mL). The combined organic layers were dried over magnesium sulfate and concentrated to afford 264 g of a racemic mixture of (4R,5R)-4-(3-chlorophenyl)-5-(4-chlorophenyl)-5-hydroxy-2-methylpentanoic acid and (4S,5S)-4-(3-chlorophenyl)-5-(4-chlorophenyl)-5-hydroxy-2-methylpentanoic acid was obtained. The crude material containing some residual solvent was used as-is in the subsequent transformation. The product (estimated after solvent correction 227 g) is a roughly 1:1 mixture of diastereomers at the 2-position. ¹H-NMR (500 MHz, CDCl₃) δ 7.31 (m, 2H), 7.25 (m, 3H), 7.17 (m, 2H), 7.05 (m, 1H) 4.74 (m, 1H), 2.99 (ddd, J = 11.2, 1.7, 3.7 Hz, 0.5H), 2.90 (ddd, J = 11.5, 7.3, 4.6 Hz, 1H), 2.15 (m, 1.5 H), 1.85 (m, 0.5 H), 1.67 (ddd, J = 14.3, 11.5, 3.4 Hz, 0.5H), 1.52 (m, 0.5 H), 1.08 (d, J = 7.1 Hz, 1.5 H), 1.05 (d, J = 6.9 Hz, 1.5H) ppm.

Alternatively, (4R,5R)-4-(3-Chlorophenyl)-5-(4-chlorophenyl)-5-hydroxy-2-methylpentanoic acid, as a mixture of methyl diastereomers, can be prepared from racemic methyl 4-(3-chlorophenyl)-5-(4-chlorophenyl)-2-methyl-5-oxopentanoate.

In a three-neck flask, a solution of racemic methyl 4-(3-chlorophenyl)-5-(4-chlorophenyl)-2-methyl-5-oxopentanoate (500 g, 1.37 mol, 1 eq) in anhydrous 2-propanol (2.5 L) was charged with KO^tBu (46.1 g, 0.41 mol, 0.3 eq) and stirred for 30 min until a clear yellow solution was formed. The solution was then treated with a solution of dichloro {(S)-(-)-2,2'-bis[di(3,5-xylyl)phosphino]-1,1'-binaphthyl}[(2S)-(+)-1,1-bis(4-methoxyphenyl)-3-methyl-1,2-butanediamine]ruthenium(II) (5 g, 4.1 mmol, 0.003 eq, Strem Chemicals inc., Newburyport, MA) in anhydrous toluene (250 mL) and stirred at RT for 2 hours (Note: Most of methyl ester was converted to isopropyl). The solution was transferred to two Parr shakers, sealed and purged with hydrogen 3 times. The reaction was shaken at RT under 414 kilopascals hydrogen pressure. After 18 hrs, the reaction was quenched with sat. NH₄Cl, concentrated and extracted with EtOAc (2 L X 2). The combined organics was washed with brine and concentrated as a brown oil and used as such in the next step.

The crude intermediate (542 g, 1.37 mol) was dissolved in THF (3 L) and MeOH (1 L) and charged with 2 M LiOH (1 L). The solution was rotated at RT overnight, concentrated to remove most of THF and MeOH, and quenched with 1 L of 2 M HCl. After phase separation, the aqueous layer was extracted with EtOAc (1 L X 2). The combined organics were washed with brine, dried over anhydrous Na₂SO₄, filtered and concentrated in vacuo. This product, (4R,5R)-4-(3-Chlorophenyl)-5-(4-chlorophenyl)-5-hydroxy-2-methylpentanoic acid, as a mixture of methyl diastereomers, was taken crude to the next step.

Step D. (5R,6R)-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methyltetrahydro-2H-pyran-2-one and (5S,6S)-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methyltetrahydro-2H-pyran-2-one

The mixture of hydroxy acid diastereomers (227 g, 643 mmol; Reference Example 15, Step C) was lactonized under Dean-Stark conditions in toluene (1.07L) with pyridine 4-methylbenzenesulfonate (PPTS, 4.84 g, 19.28 mmol) under an atmosphere of nitrogen. After 2 h of vigorous reflux the solution was cooled to ambient temperature and transferred to a separatory funnel. The flask residue was rinsed in with ethyl acetate. The combined organic phase was washed in succession with water (1x250mL), sat. sodium bicarbonate solution (1 x 250 mL), and sat. aq. NaCl solution (1 x 250 mL). After drying with magnesium sulfate, concentration under reduced pressure provides a mixture of diastereomeric lactones as a light brown solid. ¹H-NMR (500 MHz, CDCl₃) δ 7.24-6.95 (series of m, 6H), 6.91 (d, J = 7.6 Hz, 0.5H), 6.82 (m, 1.5H), 6.73 (d, J = 7.6 Hz, 0.5H), 5.77 (d, J = 3.9 Hz, 0.5H), 5.69 (d, J = 4.6 Hz, 0.5H), 3.67 (dt, J = 7.6, 4.2 Hz, 0.5H), 3.55 (td, J = 7.8, 4.6 Hz, 0.5H), 2.97 (m, 0.5 H), 2.81 (doublet of quintets, J =14.4, 7.1 Hz, 0.5 H), 2.56 (dt, 16.1, 8.0 Hz, 0.5H), 2.32 (dt, J = 13.7, 6.9 Hz, 0.5H), 2.07 (ddd, J = 13.2, 8.6, 4.4 Hz, 0.5H), 1.85 (ddd, J = 14.2, 12.7, 7.6 hz, 0.5H), 1.41 (d, J = 7.1 Hz, 1.5H), 1.39 (d, J = 6.9 Hz, 1.5H) ppm.

Step E: (3S,5R,6R)-3-Allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methyltetrahydro-2H-pyran-2-one and (3R,5S,6S)-3-Allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methyltetrahydro-2H-pyran-2-one

A solution of racemic lactone from the previous step (Reference Example 15, Step D, 190.28 g, 568 mmol) in THF (946 mL) was prepared in a 1 neck round bottomed flask equipped with a Claisen adapter, 500mL dropping funnel, and internal temperature probe under an atmosphere of nitrogen. The solution was cooled to a temperature of -35°C. Allyl bromide (120 mL, 1.42 mol) was added via the addition funnel, maintaining the temperature below - 30°C during addition. A solution of LHMDS (1M in THF, 738 mL, 738 mmol) was added dropwise to the reaction, maintaining the temperature below -30°C. The reaction was allowed to slowly warm to -5°C over a period of 1h. The solution was recooled to about -20°C and added via cannula into a solution of ammonium chloride in water at about 5C. After separation of the layers, the aqueous layers were extracted twice with ethyl acetate. The combined organic layers were washed with sat. aq. NaCl solution and dried over sodium sulfate. Concentration under vacuum provided 219 g of a light yellow solid. The solids were slurried at ambient temperature for 2 h with hexane (2 L). The solids were then collected by filtration, rinsed with hexane (2 X 100 mL) and dried to provide the title compounds as a racemic mixture. ¹H-NMR (500 MHz, CDCl₃) δ 7.24 (m, 1H), 7.20-7.15 (m, 3H), 6.91 (t, J = 1.7 Hz, 1H), 6.77 (d, J = 7.6 Hz, 1H), 6.59 (m, 2H), 5.84 (ddt, J = 17.6, 10.3, 7.6 Hz, 1H), 5.71 (d, J = 5.4 Hz, 1H), 5.21-5.13 (m, 2H), 3.81 (dt, J = 12.0, 4.2 Hz, 1H), 2.62 (ABX J_AB = 14.0, J_AX = 7.8 Hz, 1H), 2.52 (ABX, J_AB = 13.9, J_AX = 7.3 Hz, 1H), 1.98 (dd, J = 14.0, 12.0 Hz, 1H), 1.91 (ddd, J = 14.0, 3.7, 1.2 Hz, 1H), 1.42 (s, 3H) ppm.

Step F: Separation of (3S,5R,6R)-3-allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methyltetrahydro-2H-pyran-2-one and (3R,5S,6S)-3-allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methyltetrahydro-2H-pyran-2-one

A racemic mixture of (3S,5R,6R)-3-allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methyltetrahydro-2H-pyran-2-one and (3R,5S,6S)-3-allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methyltetrahydro-2H-pyran-2-one can be separated using chiral Supercritical Fluid Chromatography (SFC) as follows: Using a 250 x 30 mm Lux2® column (Phenomenex, Torrance, CA 90501, USA)with 20 g/min methanol (20 mM NH3) + 60 g/min CO₂ on a Thar 80 SFC. Outlet pressure = 100 bar; Temp. = 23C; Wavelength = 220 nm. Used 0.3 mL injections of 5.0 g/ 80 mL (62.5 mg/mL sample solution in methanol/ dichloromethane (75:5), i.e. 18.75 mg/injection. Run time = 8 min, Cycle time = 3 min.

The first peak collected was assigned as (3R,5S,6S)-3-allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methyltetrahydro-2H-pyran-2-one. The second peak collected was determined to be (3S,5R,6R)-3-allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methyltetrahydro-2H-pyran-2-one by subsequent chemical derivatization with (S)-2-amino-1-butanol and conversion to the same compound as prepared in Reference Example 4, Step B, by the procedures described for Reference Example 15, Steps G and H. The NMR of the separated enantiomers was consistent with the spectrum of the racemate described above.

Alternatively, (3S,5R,6R)-3-allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methyltetrahydro-2H-pyran-2-one can be prepared from racemic methyl 4-(3-chlorophenyl)-5-(4-chlorophenyl)-2-methyl-5-oxopentanoate.

In a three-neck flask, a solution of racemic methyl 4-(3-chlorophenyl)-5-(4-chlorophenyl)-2-methyl-5-oxopentanoate (500 g, 1.37 mol, 1 eq) in anhydrous 2-propanol (2.5 L) was charged with KO^tBu (46.1 g, 0.41 mol, 0.3 eq) and stirred for 30 mins until a clear yellow solution was formed. The solution was then treated with a solution of Dichloro {(S)-(-)-2,2'-bis[di(3,5-xylyl)phosphino]-1,1'-binaphthyl}[(2S)-(+)-1,1-bis(4-methoxyphenyl)-3-methyl-1,2-butanediamine]ruthenium(II) (5 g, 4.1 mmol, 0.003 eq, /Strem Chemicals Inc., Newburyport, MA) in anhydrous toluene (250 mL) and stirred at RT for 2 hours (Note: Most of methyl ester was converted to isopropyl). The solution was transferred to two Parr shakers, sealed and purged with hydrogen 3 times. The reaction was shaken at RT under 414 kilopascals hydrogen pressure. After 18 hrs, the reaction was quenched with sat. NH₄Cl, concentrated and extracted with EtOAc (2 L x 2). The combined organics was washed with brine and concentrated as a brown oil and used as such in the next step.

The crude intermediate (542 g, 1.37 mol) was dissolved in THF (3 L) and MeOH (1 L) and charged with 2 M LiOH (1 L). The solution was rotated at RT overnight, concentrated to remove most of THF and MeOH, and quenched with 1 L of 2 M HCl. After phase separation, the aqueous layer was extracted with EtOAc (1 L x 2). The combined organics was washed with brine, dried over anhydrous Na₂SO₄, filtered and concentrated in vacuo.

Step G: (S)-2-((2R,3R)-2-(3-Chlorophenyl)-3-(4-chlorophenyl)-3-hydroxypropyl)-N-((S)-1-hydroxy-3-methylbutan-2-yl)-2-methylpent-4-enamide

A mixture of (S)-2-amino-3-methylbutan-1-ol (550 mg, 5.33 mmol) and (3S,5R,6R)-3-allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methyltetrahydro-2H-pyran-2-one (Reference Example 15, Step H, 2^nd compound, 500 mg, 1.332 mmol) was heated to 100°C for 24h. After cooling to room temperature, the residue was dissolved in ethyl acetate and washed 3X with 1N HCl (5 mL) followed by sat. aq. NaCl solution (5 mL). The organic phase was dried over MgSO₄, filtered, and the filtrate was concentrated to afford the title compound. ¹H-NMR (500 MHz, DMSO-d₆) δ 7.21 (m, 2H), 7.10 (m, 2H), 7.06 (br s, 1H), 6.99 (m, 2H), 6.86 (br d, J = 8.8 Hz, 1H), 6.84 (br d, J = 7.1 Hz, 1H), 5.53 (dddd, J = 16.9, 10.3, 8.1, 6.6 Hz, 1H), 5.46 (d, J = 4.4 Hz, 1H), 4.90 (m, 2H), 4.78 (t, J = 4.2 Hz, 1H), 4.56 (t, J = 5.1 Hz, 1H), 3.56 (m, 1H), 3.37 (m, 2H), 2.87 (dt, J = 7.8, 4.2 Hz, 1H), 2.29 (dd, J = 13.7, 6.4 Hz, 1H), 2.14 (dd, J = 14.4, 7.8 Hz, 1H), 1.97 (dd, J = 14.4, 3.9 Hz, 1H), 1.88 (dd, J = 13.9, 8.1 Hz, 1H), 1.76 (octet, J = 6.4 Hz, 1H), 0.97 (s, 3H), 0.81 (d, J = 6.8 Hz, 3H), 0.75 (d, J = 6.6 Hz, 3H) ppm.

Step H. (3S,5R,6S)-3-Allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-1-((S)-1-hydroxy-3-methylbutan-2-yl)-3-methylpiperidin-2-one

(S)-2-((2R,3R)-2-(3-Chlorophenyl)-3-(4-chlorophenyl)-3-hydroxypropyl)-N-((S)-1-hydroxy-3-methylbutan-2-yl)-2-methylpent-4-enamide (reference example 15, step G) was transferred as a solution in anhydrous benzene to a pre-weighed, oven-dried 50 mL round bottom flask and stripped to dryness. Azeotropic distillation of benzene/water was performed twice more, and the residue was dried under high vacuum for 2 h, after which it weighed 550 mg. An oven-dried stir bar was added to the flask. The vessel was sealed and purged with nitrogen and then anhydrous dichloromethane (23 mL) was added, followed by triethylamine (1.3 mL, 9.33 mmol). The resulting stirred solution was cooled to 0 °C. Methanesulfonyl chloride (0.270 mL, 3.49 mmol) was added dropwise by microsyringe. After 1 h, the reaction was quenched by addition of HCl (1.2M, 12 mL) and diluted in ethyl acetate. The organic layer was washed with 1.2 M HCl (30 mL), saturated sodium bicarbonate (2 X 25 mL), and sat. aq. NaCl solution. After drying over magnesium sulfate and concentration in vacuo an intermediate was obtained as an off-white foam (0.64 g,). 1,8-Bis(dimethylamino)naphthalene, 314 mg, 1.465 mmol) and water (0.104 mL, 5.75 mmol) were added to the intermediate, followed by dioxane (23 mL). The mixture was heated under nitrogen at 110 °C overnight. After cooling, the mixture was dissolved in ethyl acetate and washed with saturated ammonium chloride solution. The aqueous phase was back-extracted with ethyl acetate. The combined organic layers were washed with sat. aq. NaCl solution, dried over sodium sulfate, filtered, and concentrated in vacuo. The residue was purified by chromatography on silica, eluting with ethyl acetate in hexanes. Chromatography fractions containing predominantly the desired product were combined. The product was re-purified by chromatography on a 40 g silica column, eluting with a gradient of 0 to 50% ethyl acetate in hexanes to give the title compound. ¹H NMR (400 MHz, CHLOROFORM-d) δ 0.73 (d, J = 6.46 Hz, 3 H), 0.83 (d, J = 6.65 Hz, 3 H), 1.28 (s, 3 H), 1.91 - 2.00 (m, 1 H), 2.00 - 2.10 (m, 1H), 2.26 - 2.45 (m, 1H), 2.56 - 2.74 (m, 2 H), 3.16 (br. s., 1H), 3.26 (ddd, J = 13.50, 10.47, 3.42 Hz, 1H), 3.43 (br. s., 1H), 3.76 (dd, J = 11.25, 3.42 Hz, 1H), 4.49 (d, J = 10.56 Hz, 1H), 5.18 (s, 1 H), 5.21 (d, J = 6.46 Hz, 1 H), 5.87 (ddt, J = 16.95, 9.85, 7.53 Hz, 1 H), 6.72 (apparent d, J = 7.63 Hz, 1 H), 6.95 (t, J = 1.66 Hz, 1 H), 6.97 - 7.17 (m, 4 H), 7.23 (d, J = 8.41 Hz, 2 H). MS (ESI) m/z = 460 [M+H]⁺.

Step I. (S)-2-((3S,5R,6S)-3-Allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methyl-2-oxopiperidin-1 -yl)-3 -methylbutanal

Dess-Martin periodinane (938 mg, 2.212 mmol) was added as a solid to a solution of (3S,5R,6S)-3-allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-1-((S)-1-hydroxy-3-methylbutan-2-yl)-3-methylpiperidin-2-one (Reference Example 15, Step H, 365.4 mg, 0.794 mmol) in dichloromethane (8 mL) and water (0.04 mL, 2.220 mmol). The resulting suspension was vigorously stirred at ambient temperature for 1.5 h. The reaction was quenched with sodium thiosulfate solution (1M aq, 6 mL). Additional sodium thiosulfate solution (1M aq, 6 mL) was added and stirred until the chalky suspension became a slightly cloudy biphasic mixture. The aqueous phase was separated and back extracted with dichloromethane. The organic layer was washed with sodium thiosulfate solution, saturated aqueous sodium bicarbonate and sat. aq. NaCl solution. After drying over sodium sulfate and concentration, the residue was purified on silica gel, eluting with a gradient of 0 to 30% ethyl acetate in hexanes. Fractions containing the desired product were pooled to give the title compound as a white foam. MS (ESI) m/z = 458 [M+H]⁺.

Step J. (3S,5R,6S)-3-Allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-1-((S)-2-hydroxy-4-methylpentan-3-yl)-3-methylpiperidin-2-one.

Methylmagnesium bromide (1.4 mL, 1.960 mmol, 1.4 M in 1:3 THF:toluene) was added by syringe to a solution under nitrogen of pre-dried (S)-2-((3S,5R,6S)-3-allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methyl-2-oxopiperidin-1-yl)-3-methylbutanal (Reference Example 15, Step I, 286 mg, 0.624 mmol) in THF (6.5 mL) at 0°C. The ice bath was removed. After 2 h, the solution was recooled to 0°C and quenched by careful addition of saturated ammonium chloride solution. The resulting mixture was extracted with ethyl acetate. The organic layer was washed with sat. aq. NaCl solution, dried over sodium sulfate, filtered, and concentrated. The residue was purified by chromatography on silica, eluting with a gradient of 0 to 40% ethyl acetate in hexanes. Fractions containing the desired product were combined and re-purified to give the title compound as a mixture of diastereomeric alcohols) as a white foam. MS (ESI) m/z = 474 [M+H]⁺.

Step K. 2-((3R,5R,6S)-5-(3-Chlorophenyl)-6-(4-chlorophenyl)-3-methyl-1-((S)-2-methyl-4-oxopentan-3-yl)-2-oxopiperidin-3-yl)acetic acid.

(3 S,5R,6S)-3-Allyl-5-(3 -chlorophenyl)-6-(4-chlorophenyl)-1-((S)-2-hydroxy-4-methylpentan-3-yl)-3-methylpiperidin-2-one (Reference Example 15, Step J, 244 mg, 0.51 mmol) was converted by a procedure similar to the one described in Reference Example 13, Step E to the title compound obtained after silica gel chromatography eluting with ethyl acetate in hexanes as a white solid. MS (ESI) 490 [M+H]⁺.

Step L. 2-((3R,5R,6S)-5-(3-Chlorophenyl)-6-(4-chlorophenyl)-1-((2S,3S)-2-hydroxy-4-methylpentan-3-yl)-3-methyl-2-oxopiperidin-3-yl)acetic acid

The title compound was obtained from 2-((3R,5R,6S)-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methyl-1-((S)-2-methyl-4-oxopentan-3-yl)-2-oxopiperidin-3-yl)acetic acid (Reference Example 15, Step K, 79.9 mg, 0.16 mmol) by a procedure similar to the one described in Reference Example 13. After workup, the material was purified by chromatography on a 24 g silica column, eluting with a gradient of 10 to 20% isopropanol in hexanes. The purest fractions were combined, concentrated, re-dissolved in 1:1 MeCN / water, passed through a pall microfilter, frozen, and lyophilized to give the title compound as a white solid. Stereochemistry assigned by analogy to reference example 8. ¹H NMR (400 MHz, Methanol-d4) δ 0.62 (d, J = 7.04 Hz, 3 H), 0.67 (d, J = 6.65 Hz, 3 H), 1.26 (d, J = 6.46 Hz, 3 H), 1.42 (s, 3 H), 2.13 - 2.29 (m, 3 H), 2.49 (t, J = 7.14 Hz, 1H), 2.62 (d, J = 13.69 Hz, 1 H), 3.01 (d, J = 13.69 Hz, 1H), 3.57 (td, J = 10.81, 6.16 Hz, 1H), 4.23 (t, J = 6.65 Hz, 1 H), 4.70 (d, J = 10.95 Hz, 1 H), 6.65 - 7.51 (m, 8 H). MS (ESI) m/z = 492 [M+H]⁺.

REFERENCE EXAMPLE 16 2-((3R,5R,6S)-5-(3-Chlorophenyl)-6-(4-chlorophenyl)-1-((S)-1-(ethylsulfonyl)butan-2-yl)-3-methyl-2-oxopiperidin-3-yl)acetic acid

Step A. (3S,5S,6R,8S)-8-Allyl-6-(3-chlorophenyl)-5-(4-chlorophenyl)-3-ethyl-8-methyl-2,3,5,6,7,8-hexahydrooxazolo[3,2-a]pyridin-4-ium trifluoromethanesulfonate

By the method of Reference Example 17 Step A using (S)-2-aminobutanol in place of L-valinol, the title compound was obtained as the first eluting diastereomer. ¹H NMR (500 MHz, DMSO-d₆) δ ppm 7.95 (1 H, br. s), 7.34 - 7.60 (2 H, m), 7.18 - 7.34 (4 H, m), 7.13 (1 H, dt, J=7.5, 1.3 Hz), 5.88 (1 H, m), 5.37 (1 H, dd, J=16.8, 1.6 Hz), 5.28 (1 H, dd, J=10.0, 2.0 Hz), 5.16 (1 H, d, J=10.8 Hz), 5.06 (1 H, t, J=9.8 Hz), 4.78 (1 H, dd, J=9.5, 7.1 Hz), 4.45 (1 H, m, J=2.7 Hz), 3.88 - 3.98 (1 H, m), 2.66 - 2.85 (2 H, m), 2.33 (1 H, t, J=13.4 Hz), 1.99 (1 H, dd, J=13.7, 3.4 Hz), 1.32 (3 H, s), 0.94 (1 H, m), 0.59 (3 H, t, J=7.2 Hz), 0.41 - 0.53 (1 H, m); Mass Spectrum (ESI) m/z = 428.2 (M⁺).

Step B. (3S,5R,6S)-3-Allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-1-((S)-1-(ethylthio)butan-2-yl)-3-methylpiperidin-2-one

To a solution of (3S,5S,6R,8S)-8-allyl-6-(3-chlorophenyl)-5-(4-chlorophenyl)-3-ethyl-8-methyl-2,3,5,6,7,8-hexahydrooxazolo[3,2-a]pyridin-4-ium trifluoromethanesulfonate (86 mg, 0.15 mmol; Reference Example 16, Step A) in DMF (0.74 ml) was added sodium ethanethiolate (38 mg, 0.45 mmol). After being stirred at 25 °C for 1.5 h, the reaction was quenched (sat. aq. NH₄Cl), extracted (2×EtOAc), and washed (2×brine). The combined organic layers were dried over Na₂SO₄, filtered and the filtrate was concentrated under reduced pressure. Purification of the residue by chromatography on silica gel (12 g SiO₂, 10% and 20% EtOAc/hex) provided the title compound as a colorless liquid.

Step C. 2-((3R,5R,6S)-5-(3-Chlorophenyl)-6-(4-chlorophenyl)-1-((S)-1-(ethylsulfonyl)butan-2-yl)-3-methyl-2-oxopiperidin-3-yl)acetic acid

To a rapidly stirring solution of (3S,5R,6S)-3-allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-1-((S)-1-(ethylthio)butan-2-yl)-3-methylpiperidin-2-one (60 mg, 0.12 mmol; Reference Example 16, Step B) in a mixture of water (0.66 mL), acetonitrile (0.44 mL), and CCl₄ (0.44 mL) was added sodium periodate (157 mg, 0.734 mmol), followed by ruthenium(III) chloride hydrate (2.8 mg, 0.012 mmol). After being vigorously stirred for 5 h, the reaction was acidified (10% citric acid) and diluted (EtOAc). The reaction mixture was filtered through a pad of Celite® (J.T. Baker, Phillipsberg, NJ, diatomaceous earth) and the filtrate was extracted (2×EtOAc). The combined organic layers were washed with brine, dried over Na₂SO₄ filtered and the filtrate was concentrated under reduced pressure. Purification of the residue by reverse phase preparatory HPLC (Gemini™ Prep C₁₈ 5 µm column, Phenomenex, Torrance, CA; gradient elution of 40% to 60% MeCN in water, where both solvents contain 0.1% TFA) provided the title compound as a white foam. ¹H NMR (400 MHz, CHLOROFORM-d) δ ppm 7.24 - 7.26 (2 H, m), 7.01 - 7.20 (4 H, m), 6.93 - 6.98 (1 H, m), 6.85 (1 H, d, J=7.0 Hz), 4.94 (1 H, d, J=10.6 Hz), 4.15 (1 H, t, J=12.1 Hz), 3.24 - 3.37 (1 H, m), 2.92 - 3.18 (4 H, m), 2.71 - 2.82 (2 H, m), 2.38 (1 H, t, J=13.8 Hz), 2.06 - 2.21 (1 H, m), 1.92 (1 H, dd, J=13.7, 2.7 Hz), 1.48 (3 H, s), 1.42 - 1.46 (1 H, m) 1.44 (3 H, t, J=7.5 Hz), 0.41 (3 H, t, J=7.5 Hz); Mass Spectrum (ESI) m/z = 540.1 [M+H.

REFERENCE EXAMPLE 17 2-((3R,5R,6S)-5-(3-Chlorophenyl)-6-(4-chlorophenyl)-1-((S)-1-(ethylsulfonyl)-3-methylbutan-2-yl)-3-methyl-2-oxopiperidin-3-yl)acetic acid

Step A. (3S,5S,6R,8S)-8-Allyl-6-(3-chlorophenyl)-5-(4-chlorophenyl)-3-isopropyl-8-methyl-2,3,5,6,7,8-hexahydrooxazolo[3,2-a]pyridin-4-ium trifluoromethanesulfonate

L-valinol (Sigma Aldrich, St. Louis, MO) (3.64 g), racemic (3S/R,5R/S,6R/S)-3-allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methyltetrahydro-2H-pyran-2-one (3. 17g; Reference Example 15, step E) and lithium t-butoxide (0.025 g) were heated as a melt for 17 hr using an oil bath set at 135 °C. After cooling, the glassy solid was dissolved in dichloromethane. The organic layer was washed with sat. ammonium chloride solution followed by IN sodium hydroxide solution and then brine. The organic layer was dried over magnesium sulfate and concentrated to give 3.88g of a mixture of diastereomers. A 2.61 g portion (67 % of total) of the ca. 1:1 mixture obtained above was dissolved in toluene and evaporated to dryness three times to remove residual moisture. Dichloromethane (55ml) and 2,6-dimethylpyridine (3.3 ml, 28.5 mmol) were added and the resulting stirred solution was cooled to - 50°C in a dry ice/acetonitrile bath. Trifluoromethanesulfonic anhydride (2.4 ml, 14.27 mmol) was added over the course of 10 minutes such that the internal temperature never exceeded - 45°C. After 40 min, the reaction was quenched by addition of 2 M HCl. The mixture was warmed to room temperature, diluted in dichloromethane, washed with 2 N HCl, water, and finally brine. The organics were dried over magnesium sulfate, filtered, and concentrated to a yellow foam that weighed ca. 2.6 g. A portion of this material (1.92 g,74 %) was purified by medium-pressure liquid chromatography using a 120 g column, eluting with a gradient of 20 to 100% acetone in hexanes. Fractions containing the faster-eluting (less polar) diastereomer were concentrated to give the title compound as a white foam. ¹H NMR (400 MHz, CDCl₃) δ ppm 0.62 (d, J = 2.4 Hz, 3 H), 0.64 - 0.74 (m, 4 H), 1.51 (s, 3 H), 2.04 (dd, J = 14.1, 3.5 Hz, 1 H), 2.54 - 2.79 (m, 3 H), 3.58 (ddd, J = 13.7, 10.8, 3.5 Hz, 1H), 4.59 (dd, J = 10.2, 4.7 Hz, 1H), 4.67 (dd, J = 9.2, 4.9 Hz, 1H), 5.23 - 5.45 (m, 3 H), 5.71 (d, J = 11 Hz, 1 H), 5.83 (ddt, J = 17, 9.9, 7.4 Hz, 1 H), 7.06 (t, J = 1.8 Hz, 1 H), 7.11 - 7.16 (m, 1 H), 7.19 (t, J = 7.7 Hz, 1 H), 7.23 - 7.32 (m, 3 H), 7.39 (br s, 2 H); Mass Spectrum (ESI) m/z = 442.2 (M⁺).

Step B. 2-((3R,5R,6S)-5-(3-Chlorophenyl)-6-(4-chlorophenyl)-1-((S)-1-(ethylsulfonyl)-3-methylbutan-2-yl)-3-methyl-2-oxopiperidin-3-yl)acetic acid

The title compound was prepared from (3S,5S,6R,8S)-8-allyl-6-(3-chlorophenyl)-5-(4-chlorophenyl)-3-isopropyl-8-methyl-2,3,5,6,7,8-hexahydrooxazolo[3,2-a]pyridin-4-ium trifluoromethanesulfonate (Reference Example 17, step A) by procedures similar to the ones described in Reference Example 16, using an equivalent amount of ethanethiol in step B. ¹H NMR (500 MHz, methanol-d₄) δ ppm 0.51 (d, J = 7.1 Hz, 3 H), 0.66 (d, J = 6.6 Hz, 3 H), 1.37 (s, 3 H), 1.41 (t, J = 7.5 Hz, 3 H), 2.05 (dd, J = 13.7, 2.9 Hz, 1H), 2.18 (dq, J = 14.2, 6.9 Hz, 1 H), 2.31 (t, J = 13.7 Hz, 1 H), 2.62 (d, J = 13.7 Hz, 1 H), 3.00 (d, J = 13.7 Hz, 1 H), 3.14 - 3.24 (m, 3 H), 3.25 - 3.30 (m, 1H), 3.57 (ddd, J = 13.8, 10.9, 2.9 Hz, 1 H), 4.02 (dd, J = 13.9, 10.5 Hz, 1 H), 5.12 (d, J = 11 Hz, 1 H), 7.00 (dt, J = 7.3, 1.5 Hz, 1 H), 7.04 - 8.17 (m, 7 H); Mass Spectrum (ESI) m/z = 554.2 (M+1).

EXAMPLE 1 2-((3R,5R,6S)-5-(3-Chlorophenyl)-6-(4-chlorophenyl)-1-((S)-1-(isopropylsulfonyl)-3-methylbutan-2-yl)-3-methyl-2-oxopiperidin-3-yl)acetic acid

The title compound was prepared from (3S,5S,6R,8S)-8-allyl-6-(3-chlorophenyl)-5-(4-chlorophenyl)-3-isopropyl-8-methyl-2,3,5,6,7,8-hexahydrooxazolo[3,2-a]pyridin-4-ium trifluoromethanesulfonate (Reference Example 17, step A) by procedures similar to the ones described in Reference Example 16, using an equivalent amount of propane-2-thiol in step B. ¹H NMR (500 MHz, methanol-d₄) δ ppm 0.50 (d, J = 6.9 Hz, 3 H), 0.65 (d, J = 6.6 Hz, 3 H), 1.37 (s, 3 H), 1.41 (d, J = 6.9 Hz, 6 H), 2.05 (dd, J = 13.6, 2.8 Hz, 1 H), 2.18 (dq, J = 14, 6.9 Hz, 1 H), 2.31 (t, J = 13.7 Hz, 1 H), 2.61 (d, J = 13.5 Hz, 1 H), 2.99 (d, J = 13.7 Hz, 1 H), 3.11 (d, J = 13.7 Hz, 1 H), 3.25 - 3.29 (m, 1 H), 3.32 - 3.37 (m, 1 H), 3.49 - 3.65 (m, 1H), 4.01 (dd, J = 13.7, 10.5 Hz, 1H), 5.13 (d, J = 11 Hz, 1H), 6.93 - 7.03 (m, 1 H), 7.03 - 8.23 (m, 7 H); Mass Spectrum (ESI) m/z = 568.0 (M+1).

Compounds of the present invention display inhibition of the interaction between HDM2 and p53 in the following assays.

Homogenous time-resolved fluorescence assay (HTRF1 assay)

The standard assay conditions for the in vitro HTRF assay consisted of a 50 ul total reaction volume in black 384-well Costar polypropylene plates in 1X PBS buffer pH 7.4, 1 mM DTT, 0.1% BSA, 2.5 nM GST-hMDM2 (aa 1-188), 5 nM biotinylated-p53 (aa 1-83), 1.8 nM SA-XLent (Cisbio; Bedford, MA), 0.6 nM anti-GST cryptate monoclonal antibody (Cisbio; Bedford, MA) and 200 mM KF. Amino acid residues 1-188 of human MDM2 were expressed as an amino-terminal glutathione-S-transferase (GST) fusion protein (GST-hMDM2) in Escherichia coli. Residues 1-83 of human p53 were expressed as an amino-terminal AviTag™-TrxA-6xHis fusion protein (biotinylated p53) in E. coli. Each protein was purified from cell paste by affinity chromatography.

Specifically, 10 uL of GST-hMDM2 was incubated with 10 ul of diluted compound (various concentrations, serially diluted) in 10% DMSO for 20 minutes at room temperature. 20 uL of biotinylated-p53 was added to the GST-hMDM2 + compound mixture, and then incubated at room temperature for 60 min. 10 uL of detection buffer consisting of SA-XLent, anti-GST cryptate antibody and KF was added to GST-hMDM2, biotinylated-p53 and compound reaction and left at room temperature to reach equilibrium for >4 hrs. The final concentration of DMSO in the reaction was 2%. Time-resolved fluorescence readings were measured on a microplate multilabel reader. Percentage of inhibition was calculated relative to nutlin-3.

As the potencies of the HDM2 inhibitors increased, an improved HTRF assay (HTRF2 assay) was developed. All assay conditions remained the same as described above, with the exception of the following changes in reagent concentrations: 0.2 nM GST-hMDM2 (1-188), 0.5 nM biotinylated-p53 (1-83), 0.18 nM SA-XLent, and 100 mM KF.

Results are provided in the table below.

Table 1

Example
Reference Example 1	0.04	0.004
Reference Example 2	0.06	0.01
Reference Example 3	0.02	0.003
Reference Example 4	0.01	0.004

Example
Reference Example 5	0.01	0.001
Reference Example 6	0.04	0.006
Reference Example 7	0.02	0.006
Reference Example 8	0.01	0.001
Reference Example 9	0.02	0.002
Reference Example 10	0.03	0.006
Reference Example 11	0.01	0.001
Reference Example 12	0.06
Reference Example 13		0.001
Reference Example 14	0.08	0.002
Reference Example 15		0.001
Reference Example 16		0.0003
Reference Example 17		0.0005
Example 1		0.0010

Compounds in the present invention display activation of cyclin-dependent kinase inhibitor p21^WAF1/CIP1.

p21 TaqMan® Assay

Inhibition of the interaction between hMDM2 and p53 results in activation of the p53 pathway via stabilization and accumulation of p53. p53 activates the transcription of many genes, one of which is p21^WAF1/CIP1. In order to assess the potency of hMDM2 inhibitors, quantitative reverse transcription polymerase chain reaction (qRT-PCR or TaqMan®) was used to measure the levels of p21 transcript in compound-treated cells relative to dimethyl sulfoxide (DMSO)-treated control cells.

On Day 1, SJSA-1 cells were plated at a density of 3x10⁴ cells/well in 96-well cell culture plates in 100 ul of growth medium (RPMI 1640; 10 mM HEPES; 1 mM sodium pyruvate; 1X Penicillin-Streptomycin-Glutamine (PSQ); and 10% fetal bovine serum (all reagents from Invitrogen; Carlsbad, CA)). The cells were cultured overnight at 37°C and 5% CO₂.

On Day 2, hMDM2 inhibitors were serially diluted in DMSO (Sigma-Aldrich; St. Louis, MO). 5 ul of each compound dilution was added to 245 ul of filtered assay medium (RPMI 1640, 10 mM HEPES, 1 mM sodium pyruvate, and 1X PSQ), containing 10% FBS. Alternatively, the assay was also run in the presence of 10% human serum or 10% mouse serum, or in the absence of any serum. The growth medium was removed from the plated SJSA-1 cells and replaced with 100 ul/well of assay medium. Then 100 ul of medium containing diluted inhibitor was added to each well, to a final volume of 200 ul. The compound dose titration yielded final concentrations ranging from 0.049 uM - 50 uM, plus a DMSO control. The cells were incubated in the presence of inhibitor at 37°C and 5% CO₂ for 7 hours. At the end of the incubation period, the medium was removed from the cells, and the plates were stored at -80°C.

On Day 3, total RNA was purified from the inhibitor- and DMSO-treated SJSA-1 cells using the Qiagen BioRobot Universal workstation following the RNeasy 96 BioRobot 8000 kit protocol from the manufacturer (Qiagen; Valencia, CA), with the following exceptions: the protocol began with RLT lysis buffer addition, omitted DNase treatment, omitted addition of Top Elute fluid, and changed the final elution volume to 120 ul. After the BioRobot Universal finished the RNA extraction procedure, the collection plate containing total RNA from each well was briefly centrifuged to collect the eluate at the bottom of the tubes.

To measure the levels of p21 transcript present, qRT-PCR was used. The levels of both p21 and the housekeeping gene, glyceraldehyde 3-phosphate dehydrogenase (GAPDH) were assayed from total RNA from each inhibitor- or DMSO-treated well in technical duplicates. Each qRT-PCR assay well contained the following components from the TaqMan® One-Step RT-PCR Master Mix Reagents Kit (Invitrogen): 10 ul of 2X TaqMan® Universal PCR Master Mix, 0.5 ul of 40X Multiscribe™ Reverse Transcriptase/RNase Inhibitor Mix, 1 ul of either p21 20X TaqMan® Gene Expression Assay (Invitrogen) or 1 ul of GAPDH 20X TaqMan® Gene Expression Assay (Invitrogen), plus 5 ul of total RNA and 3.5 ul of DEPC-H₂O (EMD Chemicals; Gibbstown, NJ). The qRT-PCR reactions were assayed on the Applied Biosystems Prism 7900HT instrument, using the relative quantification (delta delta Ct) method with the following cycling conditions: 30 minutes at 48°C, followed by 10 minutes at 95°C, then 40 cycles of 15 seconds at 95°C and 1 minute at 60°C. The data were analyzed with Applied Biosystems SDS2.2 software, using GAPDH as the endogenous control and DMSO-treated samples as the calibrator. The SDS2.2 software calculated relative quantification (RQ) or fold increase of p21 levels relative to DMSO control for each treated sample. Maximum (100%) p21 fold induction was defined by the maximum of a fitted curve of a reference compound. The p21 fold induction at each inhibitor dose tested was converted to a value representing percentage of maximum. Dose-response curves were generated using XLFit software (ID Business Solutions, Alameda, CA) to calculate IC₅₀ transit values for each inhibitor tested.

Claims

A pharmaceutical composition comprising a compound of formula or a pharmaceutically acceptable salt, ester, or amide thereof, together with a pharmaceutically acceptable excipient, diluent or carrier, wherein the pharmaceutical composition is a solid dosage form, is a composition suitable for parenteral injection, or is a liquid dosage form for oral administration; and wherein the pharmaceutically acceptable ester is selected from C₁-C₈ alkyl esters, C₅-C₇ cycloalkyl esters and arylalkyl esters; and the pharmaceutically acceptable amide is selected from amides derived from ammonia, primary C₁-C₈ alkyl amines, secondary C₁-C₈ dialkyl amines and secondary amines in the form of a 5- or 6-membered heterocycloalkyl group containing at least one nitrogen atom.
The pharmaceutical composition of claim 1, wherein the solid dosage form is a capsule, tablet, powder, or granule.
The pharmaceutical composition of claim 2, wherein the solid dosage form is a tablet.
The pharmaceutical composition of any one of claims 1 to 3, wherein the solid dosage form is for oral administration.
A compound of formula or a pharmaceutically acceptable salt, ester or amide thereof, wherein the pharmaceutically acceptable ester is selected from C₁-C₈ alkyl esters, C₅-C₇ cycloalkyl esters and arylalkyl esters and the pharmaceutically acceptable amide is selected from amides derived from ammonia, primary C₁-C₈ alkyl amines, secondary C₁-C₈ dialkyl amines and secondary amines in the form of a 5- or 6-membered heterocycloalkyl group containing at least one nitrogen atom, for use in a method of treating cancer in a subject in need thereof, the method comprising administering to the subject an effective dosage amount of the compound, or a pharmaceutically acceptable salt thereof, wherein the cancer is selected from
(a) carcinomas, which comprise cancer of the bladder, breast, colon, rectum, kidney, liver, lung, esophagus, gall-bladder, ovary, pancreas, stomach, cervix, thyroid, prostate, and skin;

(b) hematopoietic tumors of lymphoid lineage, which comprise leukemia, acute lymphocytic leukemia, chronic myelogenous leukemia, acute lymphoblastic leukemia, B-cell lymphoma, T-cell-lymphoma, Hodgkin's lymphoma, non-Hodgkin's lymphoma, hairy cell lymphoma and Burkett's lymphoma;

(c) hematopoietic tumors of myeloid lineage, which comprise acute and chronic myelogenous leukemias, myelodysplastic syndrome and promyelocytic leukemia;

(d) tumors of mesenchymal origin, which comprise fibrosarcoma and rhabdomyosarcoma, and other sarcomas, which comprise soft tissue sarcomas and bone sarcomas;

(e) tumors of the central and peripheral nervous system, which comprise astrocytoma, neuroblastoma, glioma and schwannomas;

(f) melanoma, seminoma, teratocarcinoma, osteosarcoma, xenoderoma pigmentosum, keratoctanthoma, thyroid follicular cancer, Kaposi's sarcoma, endometrial cancer, head and neck cancer, glioblastoma, malignant ascites, or hematopoietic cancers.
The compound for use in a method of treating cancer in a subject in need thereof of claim 5, wherein the cancer is a hematopoietic tumor of lymphoid lineage.
The compound for use in a method of treating cancer in a subject in need thereof of claim 5, wherein the cancer is soft tissue sarcoma.
The compound for use in a method of treating cancer in a subject in need thereof of claim 5, wherein the cancer is breast cancer.
The compound for use in a method of treating cancer in a subject in need thereof of claim 5, wherein the cancer is glioblastoma.
The compound for use in a method of treating cancer in a subject in need thereof of claim 5, wherein the cancer is acute myeleogenous leukemia (AML).
The compound for use in a method of treating cancer in a subject in need thereof of claim 5, wherein the cancer is melanoma.
The compound for use in a method of treating cancer in a subject in need thereof of claim 5, wherein the cancer is myelodysplastic syndrome.
The compound for use in a method of treating cancer in a subject in need thereof of any one of claims 5-12, wherein the cancer is identified as p53wildtype (p53WT).
A medicament comprising the compound as depicted in claim 1 for use in a method of treating cancer in a subject in need thereof.
The medicament comprising the compound as depicted in claim 1 for use in a method of treating cancer in a subject in need thereof according to claim 14, wherin the cancer is as defined in any one of claims 5 - 13.
The medicament for use of claim 14 or 15, wherein the medicament is to be used in combination with radiation therapy.
A pharmaceutically acceptable ester, amide or a prodrug of the compound wherein the pharmaceutically acceptable ester is selected from C₁-C₈ alkyl esters, C₅-C₇ cycloalkyl esters and arylalkyl esters, the pharmaceutically acceptable amide is selected from amides derived from ammonia, primary C₁-C₈ alkyl amines, secondary C₁-C₈ dialkyl amines and secondary amines in the form of a 5- or 6-membered heterocycloalkyl group containing at least one nitrogen atom; and the prodrug is selected from esters formed by the replacement of the hydrogen atom of the acid group by a group selected from (C₂-C₁₂)alkanoyloxymethyl, 1-(alkanoyloxy)ethyl having from 4 to 9 carbon atoms, 1-methyl-1-(alkanoyloxy)ethyl having from 5 to 10 carbon atoms, alkoxycarbonyloxymethyl having from 3 to 6 carbon atoms, 1-(alkoxycarbonyloxy)ethyl having from 4 to 7 carbon atoms, 1-methyl-1-(alkoxycarbonyloxy)ethyl having from 5 to 8 carbon atoms, N-(alkoxycarbonyl)aminomethyl having from 3 to 9 carbon atoms, 1-(N-(alkoxycarbonyl)aminomethyl having from 4 to 10 carbon atoms, 3-phthalidyl, 4-crotonolactonyl, gamma-butyrolacton-4-yl, di-N,N-(C₁-C₂)alkylamino(C₂-C₃)alkyl (such as β-dimethylaminoethyl), carbamoyl-(C₁-C₂)alkyl, N,N-di(C₁-C₂)alkylcarbamoyl-(C₁-C₂)alkyl and piperidino-, pyrrolidino- or morpholino(C₂-₃)alkyl.
A pharmaceutical composition comprising the ester, amide or prodrug of the compound according to claim 17.