HK40007932B - Processes and intermediates for preparing a btk inhibitor - Google Patents

Description

Methods and intermediates for the preparation of BTK inhibitors

Technical Field

This invention relates to synthetic procedures and synthetic intermediates of substituted bicyclic compounds, particularly compounds used as pharmaceuticals, such as Bruton's tyrosine kinase (BtK) inhibitors like ibrutinib.

Background Technology

Ibrutinib is a small organic molecule with the IUPAC name 1-[(3R)-3-[4-amino-3-(4-phenoxyphenyl)pyrazolo[3,4-d]pyrimidin-1-yl]piperidin-1-yl]prop-2-en-1-one.

It has been described in several published documents, including international patent application WO 2008/039218 (Example 1b), and is described as an irreversible inhibitor of Btk.

Btk plays a crucial role in B cell signaling pathways that link activation of cell surface B cell receptors to downstream intracellular responses. Btk is a key regulator of B cell development, initiation, signal transduction, and survival (Kurosaki, Curr Op Imm [New Insights in Immunology], 2000, 276-281; Schaeffer and Schwartzberg, Curr Op Imm 2000, 282-288). Furthermore, Btk plays a role in several other hematopoietic cell signaling pathways, such as Toll-like receptor (TLR) and cytokine receptor-mediated TNF-α production in macrophages, IgE receptor (Fcepsilon RI) signaling in mast cells, inhibition of Fas/APO-1 apoptosis signaling in B lymphocytes, and collagen-stimulated platelet aggregation. See, for example, C.A. Jeffries et al., (2003), Journal of Biological Chemistry 278:26258-26264; N.J. Horwood et al., (2003), The Journal of Experimental Medicine 197:1603-1611; Iwaki et al., (2005), Journal of Biological Chemistry 280(48):40261-40270; Vassilev et al., (1999), Journal of Biological Chemistry 274(3):1646-1656; and Quek et al., (1998), Current Biology 8(20):1137-1140.

Ibrutinib has been approved in several countries, including the United States and the European Union, for the treatment of certain hematologic malignancies and is being investigated in clinical trials for other hematologic malignancies. These malignancies include chronic lymphocytic leukemia, mantle cell lymphoma, diffuse large B-cell lymphoma, and multiple myeloma.

The synthesis of ibrutinib utilizes chiral hydroxypiperidines. The object of this invention is to find alternative and/or improved methods for obtaining chiral hydroxypiperidines, and for such compounds to be used as intermediates or structural units in the synthesis of ibrutinib. A known method for preparing chiral hydroxypiperidines is described, for example, by Ju et al., *Org. Process Res. Dev*, 2014, 18(6), pp. 827-830, in which a biocatalytic method is employed to reduce the corresponding ketone using KRED (and NADH/NAD).

Various strategies can be used to introduce chiral centers, including enzymatic strategies. For example, various enzymes can be used to promote kinetic resolution (which can be called enzymatic kinetic resolution). For such a method, considering that only one enantiomer is converted in the racemic mixture, the maximum theoretical yield would be 50%. However, kinetic resolution overcomes the yield limitation by racemicizing the remaining unreacted enantiomer, thus achieving a more complete conversion. Many catalysts can fulfill this role, such as organometallic catalysts like ruthenium complex catalysts, some of which may be known.

Several other publications disclose enzymatic resolution methods, including, for example, Biocatalysis et al., 1994, Vol. 9, pp. 61-69, “Enzymatic Resolutions of Heterocyclic Alcohols”, Tatsuya Kikuchi et al., J. Labelled Cpd. Radiopharm, 44, 31-41 (2001), Lihammar et al., Adv. Synth. Catal., 2011, 353, 2321-2317, and patent document JP2001002637.

However, these documents only disclose enzymatic methods leading to specific stereochemistry or configurations of the final product. For example, an article discloses the use of enzymes to resolve some heterocyclic alcohols. Specifically, the 1-methyl-hydroxy-piperidine ring is first converted to an acetate via transesterification, and then enzymatic hydrolysis proceeds with varying degrees of success. This document does not disclose the enzymatic kinetics of the acylation reaction. An article by Tatsuya Kikuchi discloses, for example, Boc-protected hydroxy-piperidines undergoing kinetic resolution mediated by enzymatic acylation with vinyl acetate, wherein the enzyme is a lipase. This reaction proceeds with a certain stereochemistry (i.e., the (R)-configuration at the relevant chiral center with the -OAc group). An article in the Lihammar journal also discloses, for example, 1-N-substituted hydroxy-piperidines undergoing kinetic resolution under enzymatic conditions in an acylation reaction, again forming the corresponding compound with the (R)-configuration at the chiral center. Finally, JP 2001002637 only discloses enantiomeric N-substituted pyrrolidine rings; furthermore, such optically active compounds are prepared from chiral precursors in stereotactic reactions rather than via enzymatic kinetic resolution methods.

Summary of the Invention

A method is now provided for preparing compounds of formula (I) in their enantiomeric form.

in

^R1 represents hydrogen or acyl group;

R ² represents a hydrogen or amino protecting group;

* indicates a chiral center with an (S) configuration;

This method includes the enzymatic kinetic resolution of compounds having formula (II).

in

^R1 represents hydrogen and ^R2 is as defined above.

Furthermore, this method is performed in the presence of an acyl donor.

This method may be referred to herein as the method of the present invention (which consists of one or more embodiments).

The method of the present invention produces enantiomer-rich compounds of formula (I), and can alternatively be described as a method for preparing compositions comprising compounds of formula (I), wherein the (S)-enantiomer is the predominantly formed enantiomer, thus providing an ee greater than 20% (and in the embodiments described herein, the ee is still greater).

The advantages of this invention, and its actual difference from previously disclosed content, lie in the selectivity and degree of conversion into the desired optically active product.

To avoid ambiguity, the starting material for compounds having formula (II) is racemic (or has low enantiomeric purity, e.g., showing less than 20% enantiomeric excess "ee"), meaning the chiral center at the attachment site of the -OR ¹ group contains an equimolar mixture of (R)- and (S)- configurations (or a substantially lower preference for one configuration over the other, e.g., less than 60% of the dominant enantiomeric). However, the corresponding chiral center of compounds having formula (I) predominantly has the (S)- configuration (and is described as an "enantiomeric-rich product").

The method of the present invention is mentioned as enzymatic resolution. Therefore, the method of the present invention is carried out in the presence of a suitable enzyme (which influences resolution, i.e., selectively reacts with one of the two enantiomers having formula (II)). A suitable enzyme may be accompanied by an acyl donor, which is discussed below.

In one embodiment, the method of the present invention is a dynamic kinetic resolution, in which the reaction process is further carried out in the presence of a racemic catalyst. For example, any one or more of the following racemic catalysts can be used:

Unless otherwise stated, alkyl groups as defined herein may be straight-chain, or, when present with a sufficient number (i.e., at least three) of carbon atoms, may be branched and/or cyclic. Furthermore, such alkyl groups may also be partially cyclic/acyclic when present with a sufficient number (i.e., at least four) of carbon atoms. Such alkyl groups may also be saturated, or, when present with a sufficient number (i.e., at least two) of carbon atoms, may be unsaturated (and thus include, for example, the "vinyl" moiety).

In the method of the present invention, the integers of ^R1 or ^R2 of a compound having formula (II) need not be the same as the corresponding integers of a compound having formula (I). Thus, the ^R1 portion of compound (II) can be hydrogen, but in the process of the method of the present invention, this group can be converted to an acyl group ⁽ in a compound having formula (I)), for example, when the enzyme is used with an acyl donor. However, what is further covered within the scope of the method of the present invention is the case where a compound having formula (I) wherein R1 is an acyl group is saponified into another compound having formula (I) wherein ^R1 is hydrogen. Similarly, in the conversion from compound (II) to (I), the integer of ^R2 can be the same (e.g., a protecting group, such as a tert-butoxycarbonyl (Boc- group)) or different. For example, in the process of the method of the present invention, the ^R2 nitrogen protecting group may be necessary on the compound having formula (II), and therefore it can remain in the resulting compound having formula (I). However, thereafter, the protecting group can be removed (i.e., deprotection) to provide a compound having formula (I), wherein ^R2 represents hydrogen. If the intention is to perform downstream chemistry (e.g., as described below), in one embodiment, ^R2 represents a protecting group (e.g., Boc) and wherein ^R2 represents a compound of formula (I) of Boc that is converted into a downstream product, as described below.

In the method of the present invention, it is assumed that a compound having formula (II) reacts in the presence of an acyl donor (and R ¹ is hydrogen), during which the acyl group can then cause attachment to a -OH group and thus form an -O-acyl moiety (i.e., a compound having formula (I) where R ¹ represents an "acyl"; for the purposes of the present invention, "acyl" is covered within the definition of "protecting group" as defined herein). Therefore, ^R1 can represent -C(O) _-C1-8 alkyl (wherein the alkyl portion is optionally substituted by one or more substituents selected from: for example, halogen (e.g., fluorine), _-OC1-6 alkyl (e.g., methoxy; which itself is optionally substituted by one or more fluorine atoms), and phenyl (which itself is optionally substituted by one or more substituents selected from halogens and _C1-3 alkyls)) or -C(O)phenyl (wherein the phenyl portion is optionally substituted by one or more substituents selected from, for example, halogens and _C1-3 alkyls), and ^R1 can form, for example, a -C(O) _{CH2 - OCH3} moiety or a -C(O) _{CH2CH2CH3 moiety} (in one embodiment, the acyl moiety of ^R1 represents _-C (O) _{CH2CH2CH3 )} . In one embodiment, the acyl donor may represent a compound having the formula ^Rx - ^R1 , wherein ^R1 is as defined above, and ^Rx represents _-OC1-8 alkyl (optionally substituted with one or more substituents selected from fluorine and _-OC1-6 alkyl; the latter alkyl moiety is optionally substituted with one or more fluorine atoms) or -O-phenyl (optionally substituted with one or more substituents selected from halogens (e.g., chlorine, fluorine, bromine), _-NO2 , _C1-6 alkyl, and _-OC1-6 alkyl; wherein the latter two alkyl moiety are themselves optionally substituted with one or more fluorine atoms). Possible substituents on the "phenyl" moiety may be attached at any position (e.g., para-position). In one embodiment, the "acyl donor" represents a butyrate ester, such _as the following compound, where ^R1 represents -C(O) _-CH2CH2CH3 (which is therefore the acyl moiety in the resulting compound having formula (I)) and where ^Rx represents a suitable moiety (e.g., as defined herein) _. However, in one embodiment, it represents a _-OC1-6 alkyl (e.g., _-OC1-3 alkyl) optionally substituted with one or more fluorine atoms, thus forming, for example, a -O-CH2 _{- CF3} moiety. Thus, in one aspect, the acyl donor is 2,2,2-trifluoroethyl butyrate or 4-fluorophenyl butyrate.

The protecting groups that can be mentioned can be described as follows:

The above further demonstrates that ^R2 is a nitrogen-protecting group. Such groups include those that lead to the formation of the following substances:

-Amide (e.g., N-acetyl)

-Optionally substituted N-alkyl (e.g., N-alkyl or optionally substituted N-benzyl)

-N-sulfonyl group (e.g., optionally substituted N-benzenesulfonyl group)

-Carbamate

-Urea

- Triphenylmethyl (triphenylmethyl), diphenylmethyl, etc.

Therefore, ^R² can be represented as:

-C(O)R ^t1 (where R ^t1 can represent _C1-6 alkyl or optionally substituted aryl);

C _1-6 alkyl, which is optionally substituted by one or more substituents selected from optionally substituted aryl groups (e.g., forming a benzyl moiety);

-S(O) _2Rt2 (where ^Rt2 may represent an optionally substituted ^aryl group); or, in one embodiment, -C(O) ^ORt3 (where ^Rt3 may represent an optionally substituted aryl group, or in another embodiment, an optionally substituted _C1-6 (e.g., _C1-4 ) alkyl group, such as tert-butyl (thus forming, for example, a tert-butoxycarbonyl protecting group, i.e., when together with an amino moiety, a tert-butylcarbamate group) or _-CH2phenyl (thus forming a carboxybenzyl protecting group));

-C(O)N( ^Rt4 ) ^Rt5 (wherein, in one embodiment, ^Rt4 and ^Rt5 independently represent hydrogen, _C1-6 alkyl, optionally substituted aryl, or -C(O) ^Rt6 , and ^Rt6 represents _C1-6 alkyl or optionally substituted aryl).

In one embodiment, ^R2 represents -C(O)OR ^t3 (where R ^t3 may represent _C1-6 alkyl, such as tert-butyl), and thus, in one aspect, the protecting group ^{of R2} is tert-butoxycarbonyl (also referred to herein as BOC or Boc group).

The method of the present invention produces enantiomeric forms or products, meaning that the produced products have an enantiomeric excess of greater than 20%, for example greater than 40%, such as more than 60%, and in one embodiment, greater than 80%. These enantiomeric-rich products can even be higher than 90% (e.g., they can consist essentially of a single enantiomeric component, thus meaning that ee can be 95% or higher, for example, more than 98% or about 100%). Such enantiomeric abundance (or ee) can be obtained directly or by further purification techniques well known to those skilled in the art. For example, the method of the present invention can produce compounds having formula (I), where R ¹ represents H or an acyl group, wherein such products are enantiomeric.

When referring to equivalents, to avoid ambiguity, this is intended to mean molar equivalents.

In one embodiment, enzymatic kinetic resolution (e.g., dynamic kinetic resolution) is performed in the presence of an enzyme and an acyl donor.

This enzyme is adapted to perform the desired resolution, i.e., to selectively react with one of the two enantiomers in a racemic mixture having formula (II) to provide a compound having formula (I) (i.e., an enantiomer-rich product).

Various screening methods can be used to identify enzymes suitable for stereoselective kinetic resolution. Suitable enzymes can be identified by screening available enzymes, for example, using high-throughput screening techniques or enrichment separation techniques. In such enrichment separation techniques, a carbon- or nitrogen-limited medium can be supplemented with an enrichment substrate. Enzymes that yield optimal results can be further selected through additional experiments (e.g., using the conditions described herein, performing the methods of the invention as described herein). The properties of enzymes can be further enhanced through enzyme engineering. For example, enzyme engineering can be used to improve reaction rates, reaction yields, and selectivity, particularly enantioselectivity. Furthermore, enzyme engineering can be used to expand the pH and temperature ranges in which enzymes can be used, as well as their tolerance to certain solvents. Enzyme engineering techniques that can be employed include rational design methods, such as site-directed mutagenesis and in vitro directed evolution techniques. Such techniques are described, for example, in K.M. Koeller and C.H. Wong, “Enzymes for chemical synthesis,” Nature, 409:232-240, and the references cited therein (incorporated herein by reference).

Enzymes can be used in the form of crude lysates or in purified form. Alternatively, enzymes can be immobilized and used as is. Immobilization techniques are known to those skilled in the art. Useful solid supports include, for example, polymer matrices such as calcium alginate, polyacrylamide, and other polymeric materials, as well as inorganic matrices, such as those used in immobilization techniques, which are advantageous because the enzyme and product can be easily separated. Furthermore, immobilized enzymes can be recycled and reused, making the method more economical. Other techniques such as cross-linked enzyme aggregates (CLEA) or cross-linked enzyme crystals (CLEC) are also suitable for this invention.

Certain enzymes found to be suitable for use in this invention include proteases and lipases. In the method of this invention, a suitable enzyme yields an enantiomer-rich product of formula (I), for example, a product with ee greater than 20%.

The enzyme can be a protease (e.g., a nonspecific protease), such as a serine protease. In one embodiment, it can be a subtilisase, such as subtilisin (which can be obtained from Bacillus subtilis or from certain types of soil bacteria such as Bacillus amyloliquefaiens). In one embodiment, the enzyme is a protease for subtilisin. Subtilisin can also be referred to by several other names, including, in particular, alkaline protease and saveinase (and may depend on the commercial source from which it is obtained). In another embodiment, the enzyme is an alkaline protease, such as alkaline protease B. In another embodiment, the enzyme is a lipase from papaya (or from papaya latex). In another embodiment, the enzyme is papain, a protease from papaya latex.

The enzyme can also be a lipase. For example, it can be a lipase expressed and secreted by a pathogenic organism. In one embodiment, the lipase can be lipase A from Candida albicans, lipase B from Candida albicans, and/or a lipase from papaya.

The reaction can also be carried out in the presence of a phosphate buffer solution used for hydrolysis.

For example, an enzymatic process can be one in which the enzyme is selected from the following:

SAV proteases (e.g., commercially available from ChiralVision; also known as "SAV") - derived from the proteome

Candida lipase B (commercially available from Almac, e.g., product AH24 and/or product AH09)

Candida lipase A (commercially available from Almark, e.g., product AH06).

Lipases derived from papaya (e.g., commercially available from Almark, such as product AH17).

Alkaline proteinase B (e.g., commercially available from Almark, product AH19)

Subtilisin (e.g., commercially available from Almark).

The use of such enzymes facilitates the selectivity of the method of the present invention, resulting in the predominant production of the (S)-configuration (preferably the (R)-configuration). A positive ee can be obtained for any of these enzymes, and in one respect, the enzyme is subtilisin or SAV (and in particular, SAV, commercially available from Chiral Vision; also referred to herein as "SAV").

For specific enzymes from the aforementioned commercial sources, further details can be obtained from the supplier, such as in the case of the Saviour protease (also known as "Saviour protease, Bacillus subtilis protease") from Chiral Vision, which is a Bacillus protease (e.g., covalently on acrylic beads) with an activity of 750 ELU/g (where ELU refers to enzyme-linked immunosorbent unit; and 1 ELU unit = 1 μmol lactate (ethyl lactate hydrolysate)/g immobilized enzyme released per minute at 25°C and pH 6.8).

A suitable amount of enzyme can be used in the method of the present invention, and it can depend on the specific enzyme selected. However, in one aspect, the method of the present invention is carried out in the presence of about 1 to 100 g/mol (e.g., between about 10 g/mol and 50 g/mol, for example about 25 g/mol). In one embodiment, these amounts are used particularly when, for example, a seviper protease catalyst is used. In this case, "per mole" means per mole of a compound having formula (II).

In one embodiment, enzymatic kinetic resolution (e.g., dynamic kinetic resolution) is carried out in the presence of an enzyme and an acyl donor, wherein the acyl donor is selected from:

Acetyl donors (e.g., isopropyl acetate, phenyl acetate, etc.)

Butyrate donors (e.g., isopropyl butyrate, 2,2,2-trifluoroethyl butyrate (TFEB), vinyl butyrate, etc.).

In one embodiment, the acyl donor is a butyrate donor, as these advantageously lead to (in some cases) improved ee and/or improved yield conversion, as shown in the experiments.

Depending on the acyl donor and/or the solvent (or conditions) used, the percentage conversion (and percentage ee of the desired product) of the method of the present invention can be increased. In one embodiment, the percentage conversion can be greater than 10%, for example greater than 20%, for example greater than 30% (about 50% in one embodiment, or greater than 50% in another embodiment) and/or the percentage ee is greater than 30%, for example greater than 50%, for example greater than 70% (greater than 90%, such as greater than 95% or about 100% in one embodiment).

In the method of the present invention, at least 1 acyl donor equivalent is used compared to a compound having formula (II). In one aspect, at least 1.5 equivalents are used (compared to a compound having formula (II)). For example, about 2 equivalents (or at least 2 equivalents) are used. In one embodiment, less than 4 (e.g., less than 3) equivalents are used, which has the advantage that the method of the present invention does not lead to a reduction (or degradation) of ee.

Advantageously, when the kinetic resolution process of the present invention is carried out in the presence of the serotonin and butyrate acyl donor, then ee can be greater than 50% (e.g., greater than 60%, such as greater than 75%, and in one aspect, greater than 90%, such as greater than 95% ee) and/or the conversion rate can be greater than 5% (e.g., greater than 10%, greater than 20% or 30%, and in one embodiment greater than 50%). The highest conversion rate can be obtained when vinyl butyrate is used.

In one embodiment, the method of the present invention is carried out in the presence of a base, such as an organic or inorganic base. Such bases that can be used include carbonate bases (e.g., sodium carbonate, calcium carbonate, barium carbonate, cesium carbonate, potassium carbonate, etc.), hydroxide bases (e.g., potassium hydroxide, lithium hydroxide, magnesium hydroxide, etc.), alkoxide bases (e.g., tert-butoxides, such as potassium tert-butoxide), amine bases (e.g., trialkylamines, such as triethylamine, dimethylaminopyridine (DMAP), etc.), amide bases (e.g., LDA or LiHMDS, i.e., lithium diisopropylamino or lithium bis(trimethylsilyl)amino) or other suitable bases (or mixtures of bases). In one embodiment, the base used is an inorganic base (e.g., sodium carbonate).

In one embodiment, at least 0.25 base equivalents (which may be a single base or a mixture of more than one, such as two different bases) are used compared to a compound having formula (II). In one embodiment, at least about 0.5 base equivalents are present (which has the advantage that even such an amount can significantly increase the reaction rate). In one embodiment, about 1, 2, 3, or 4 base equivalents are present (compared to a compound having formula (II)). With 2 equivalents (or more) of base, only a slight increase in conversion can be observed. Therefore, in one embodiment, base equivalents (e.g., inorganic bases, such as carbonates, such as sodium carbonate) between about 0.5 and 1.5 (e.g., about 1) are used. It can be seen that different bases can lead to different reaction efficiencies and/or different yields or purities of the desired product.

In one embodiment, the method of the present invention is carried out in the presence of a suitable solvent. Suitable solvents include solvents such as aromatic solvents (e.g., toluene, pyridine), ethers (e.g., dioxane, THF (tetrahydrofuran), EtOAc (ethyl acetate), methyl tert-butyl ether, 2-methyltetrahydrofuran), alcohols (e.g., propanol, tert-amyl alcohol), alkanes (e.g., heptane, cyclohexane), etc. In one embodiment, the solvent will be the one that achieves the highest conversion while maintaining a high ee. The aforementioned alcohols all help to ensure that the product obtained by the method of the present invention (compound having formula (I)) maintains a high ee (greater than 90% in one embodiment). In one embodiment, the solvent used in the method of the present invention can be toluene or methyl-THF. Such solvents may have the advantage that they achieve the fastest conversion (and maintain a high ee; for example, as described herein). For example, at a reaction temperature of 30°C, the reaction of a compound of formula (II) where ^R2 is Boc and ^R1 is hydrogen was carried out using seviper protease as the enzyme (25 g/mol), DIPEA as the base (1 equivalent compared to the compound of formula (II), vinyl butyrate as the acyl donor (2 equivalents compared to the compound of formula (II)) and a diluted solvent of 1 L/mol. Different solvents gave different conversions (and different conversion rates): in this case, toluene gave a conversion of more than 20% in 10 hours and more than 50% in 50 hours (and for the desired product of formula (I) where ^R2 is Boc and ^R1 is -C(O) _{-C3H7 )} , maintaining an ee of 94.8%; in this case, Me-THF gave a conversion of about 15% in 10 hours and more than 40% (but less than 50%) in 50 hours (maintaining an ee of 97.2% for the same desired product).

In order to carry out the method of the present invention using a solvent, the solvent ratio per mole of the compound having formula (II) should be reasonable to ensure efficient conversion of the compound having formula (II) to the compound having formula (I). For example, a suitable amount of solvent may be between about 0.25 L/mol (compared to the mole of the compound having formula (II)) and 6 L/mol (e.g., between about 0.25 L/mol and 4 L/mol). In one embodiment, a solvent between about 0.5 L/mol and 1.5 L/mol (e.g., about 1 L/mol) is used.

In one embodiment, the reaction temperature of the method of the present invention is between about 0°C and about 60°C, but depends on how the temperature affects the ee of the final product (balanced with the possible increase in conversion that may result from increased temperature). For example, in one embodiment, the temperature is kept below about 50°C because higher temperatures may lead to a decrease (or degradation) in ee. In another embodiment, the temperature is kept above room temperature (e.g., above about 25°C) because this may have a positive effect on the reaction rate and, in particular, on the conversion. In one embodiment, the method of the present invention is carried out at a temperature between about 25°C and 40°C (e.g., between about 25°C and 35°C), such as at about 30°C.

The method of the present invention can also be made to react for a suitable period of time. For example, the progress of the reaction can be monitored (e.g., by thin-layer chromatography), and the duration can be a period of time between about 1 hour and about 72 hours. In one embodiment, the reaction time can be between about 12 hours and about 48 hours (e.g., between about 16 and 48 hours, such as between 24 and 48 hours, such as about 40 hours).

The result of the method of this invention is actually kinetic resolution, the conditions of which are discussed herein. In the case of kinetic resolution that is not dynamic kinetic resolution, then standard conditions can be used to remove or separate any unwanted products (e.g., unreacted starting materials).

In another aspect of the invention, a method is provided for separating the product (a compound having formula (I)) (hereinafter referred to as "the compound of the invention") obtained from the method of the invention. Thus, the compound of the invention (or the product obtained by the method of the invention) can be separated/isolated. This can be achieved in several ways:

- Rapid column chromatography

-Precipitation/Crystallization

- Derivatization, optional subsequent precipitation/crystallization

- Extraction (e.g., derivatization followed by extraction)

- Distillation

In one aspect, the method is derivatization, for example, in which an undesirable product (e.g., unreacted starting material) is derived (e.g., by reacting with succinic anhydride to form a group having a terminal carboxylic acid moiety), which allows for possible separation, extraction, or isolation (e.g., the carboxylic acid can be removed in a post-processing procedure).

In another embodiment of the invention, the method of the invention as described herein is provided, followed by further method steps.

Compounds having formula (I) (in an enantiomeric form) can be used to prepare other compounds, such as other pharmaceutical products (or intermediates thereof), such as pharmaceutical products for treating cancer (e.g., hematologic malignancies), and in particular, such pharmaceutical products may be ibrutinib.

Ibrutinib can be prepared according to the following protocol in WO 2008/039218 (Example 1b):

First, 4-amino-3-(4-phenoxyphenyl)-1H-pyrazole[3,4-d]pyrimidine can be prepared according to the procedure described in WO 2008/039218 (which is specifically incorporated herein by reference), for example by converting 4-phenoxybenzoic acid to the corresponding acyl chloride (using thionyl chloride), the latter product can be reacted with malononitrile to prepare 1,1-dicyano-2-hydroxy-2-(4-phenoxyphenyl)ethylene. The methoxy moiety is then methylated using trimethylsilyldiazomethane, and the methylated product is treated with hydrazine hydrate to provide 3-amino-4-cyano-5-(4-phenoxyphenyl)pyrazole, which reacts with formamide to provide 4-amino-3-(4-phenoxyphenyl)-1H-pyrazole[3,4-d]pyrimidine, as illustrated in the following scheme:

Subsequently, 4-amino-3-(4-phenoxyphenyl)-1H-pyrazole[3,4-d]pyrimidine can possess the necessary piperidinium moiety introduced at the 1H- position (i.e., on the -NH of the pyrazole moiety). This is accomplished via photoelongation reaction, as noted in the above scheme—more specifically, by converting the hydroxyl moiety of the Boc-protected 3-hydroxypiperidine-1-carboxylate into a better leaving group, thereby allowing substitution (inversion) with the -NH moiety of the pyrazole. Thus, the chiral conversion of the hydroxypiperidine is incorporated into the product, which is then converted to a single enantiomer, ibrutinib, via Boc deprotection and acylation with acryloyl chloride.

Other transformations (of products obtained directly by the methods of the present invention or of other products which may be generated from the downstream steps described herein) can be carried out according to standard techniques and steps in the prior art, such as amide formation reactions (in which case the possible conditions and coupling agents will be known to those skilled in the art), esterification, nucleophilic substitution reactions, and aliphatic nucleophilic substitution reactions.

Example

The following examples are intended to illustrate the invention and should not be construed as limiting the scope of the invention.

Example 1

General procedure for dynamic splitting and screening

Option A

Kinetic resolution screening was performed in 96-well plates at a scale of 0.25 mmol. The enzyme (25 g/mol) was weighed and placed in each well along with _Na₂CO₃ (1 _equivalent ; compared to the starting material "Compound A"). A stock solution (0.25 mL) of the corresponding acyl donor (2 equivalents) in toluene was then added, followed by a stock solution (0.25 mmol, 0.25 mL) of the compound having formula (II) (where ^R₂ is Boc and ^R₁ is hydrogen (i.e., racemic-3-hydroxy-N-Boc-piperidine), referred to as Compound A in Scheme A above). Finally, toluene (0.5 mL) was added to bring the total reaction volume to 1 mL. The wells were then sealed with a silicone sealant and placed on a shaker. The mixture was shaken at 500 rpm and 40 °C.

Sampling was performed as follows: 50 μL of the reaction mixture was transferred to another plate, 0.9 mL of EtOAc was added, and the plate was centrifuged at 3000 rpm for 15 minutes. An aliquot of the supernatant (0.5 mL) was collected and diluted with 0.5 mL of EtOAc and analyzed by chiral gas chromatography (“GC”). The conversion rate referred to here is the desired compound having formula (I), where ^R2 is Boc and ^R1 is an acyl group as defined herein (and depends on the acyl donor used in the corresponding reaction) – referred to as compound B in scheme A above.

In the table above, to measure ee and conversion, ee is based on the area ratio of the two possible enantiomers (i.e., in this case, compound B and its enantiomers). Conversion is the ratio of the sum of the two enantiomers of compound B to the sum of the two enantiomers of the starting material compound A, multiplied by the relative response factor (and thus refers to percentage conversion, which in this case usually refers to the conversion of compound A to compound B plus its enantiomers).

General procedures for large-scale reactions:

Racemic 3-hydroxy-N-Boc-piperidine, i.e., compound A (80 mmol, 16.10 g), seviperidine (25 g/mol, 2.00 g), and toluene (80 mL) were charged into a 100 mL reactor. Finally, DIPEA (80 mmol, 16 mL) and vinyl butyrate (1.1 equivalent, 11 mL) were added to the reaction mixture. The reaction was post-treated after 42 hours. The mixture was filtered. The mother liquor was extracted with acidic water (pH < 2, 3 × 100 mL). The organic layer was then dried over _MgSO₄ and concentrated under vacuum. Rapid column chromatography (heptane:EtOAc, 95% → 90% → 40% heptane) was used (TLC R _f “compound C”: 0.7, R _f “compound B”, where R ¹ is -C(O)-( _CH₂ ) _₂CH₃ : _0.2 in 7:3 heptane:EtOAc). This yields (S)-"butyrate" compound B (3-(S)-butyryloxy-N-Boc-piperidine) as a colorless oil (9.29 g, 31.7% yield, 97.8% ee) and (R)-alcohol compound C as a colorless oil after standing (11.06 g, 51.0% yield, 61.8% ee).

Post-treatment modification of succinic anhydride:

The general procedure for a large-scale EasySampler reaction was used. After 44 hours, the reaction mixture was filtered, and the filtrate was transferred to a clean 100 mL EasyMax reactor. Succinic anhydride (4.80 g, 48 mmol) was added along with 4-dimethylaminopyridine (0.24 g, 2 mmol). The reaction mixture was then heated at 50 °C for 18 hours. The mixture was then transferred to a separatory funnel, water (25 mL) and _NaHCO3 (saturated, 25 mL) were added, and the layers were separated. The aqueous layer was extracted twice with toluene (50 mL and 30 mL). The organic layers were combined, extracted with HCl (1 M, 100 mL), and dried over _MgSO4 . The volatiles were then removed under vacuum to give (S)-"butyrate" compound B (8.056 g, 50.1% yield, 97.5% ee) as a brown liquid.

Another example A: Ibrutinib (or its salt) is prepared by using any of the preparation intermediates described in Example 1 and then converting them into ibrutinib (or its salt).

Another example B: A pharmaceutical composition was prepared by first preparing ibrutinib (or its salt) according to Example 2, and then contacting the ibrutinib (or its salt) thus obtained with a pharmaceutically acceptable carrier, diluent and/or excipient.

Claims (18)

1. A method for preparing a compound of formula (I) in its enantiomeric form, in ^R1 represents hydrogen or acyl group; R ² represents a hydrogen or amino protecting group, wherein the amino protecting group represents -C(O)OR ^t3 , wherein R ^t3 represents a C _1-6 alkyl group; * represents a chiral center having an (S) configuration; This method includes the enzymatic kinetic resolution of compounds having formula (II). in ^R1 represents hydrogen and ^R2 is as defined above. Furthermore, the method is carried out in the presence of a serotonin and an acyl donor, wherein the acyl donor is trifluoroethyl acetate, o-cresol 2-methoxyacetic acid ester, or butyrate acyl donor. 2. The method of claim 1, wherein ^Rt3 represents tert-butyl. 3. The method of claim 1, wherein the butyrate acyl donor is vinyl butyrate, isopropyl butyrate, phenyl butyrate, or 2,2,2-trifluoroethyl butyrate. 4. The method of claim 3, wherein the phenyl butyrate is 3-fluorophenyl butyrate or 4-fluorophenyl butyrate. 5. The method of claim 1, wherein the acyl donor is 2,2,2-trifluoroethyl butyrate or 4-fluorophenyl butyrate. 6. The method of claim 1 or 2, wherein at least one equivalent of an acyl donor is used compared to the compound having formula (II). 7. The method of claim 6, wherein about 2 equivalents of an acyl donor are used compared to the compound having formula (II). 8. The method of claim 1 or 2, wherein the method is carried out in the presence of an inorganic base. 9. The method of claim 8, wherein the inorganic base is sodium carbonate. 10. The method of claim 1 or 2, wherein the method is carried out in the presence of a suitable solvent. 11. The method of claim 10, wherein the solvent is toluene or methyl-THF. 12. The method of claim 1 or 2, wherein the method is performed at a temperature between 25°C and 40°C. 13. The method of claim 1 or 2, wherein the method is performed at a temperature between 25°C and 35°C. 14. The method of claim 1 or 2, wherein the method is performed at about 30°C. 15. The method of claim 1 or 2, wherein the resolution is a dynamic kinetic resolution performed in the presence of a racemic catalyst. 16. The method of claim 15, wherein the racemic catalyst is one or more catalysts selected from: 17. A method for preparing ibrutinib, comprising: The method described in any one of the preceding claims yields a compound having formula (I); and Use the following steps to convert to ibrutinib: 18. A method for preparing a pharmaceutical composition comprising ibrutinib, the method comprising the process for preparing ibrutinib or a salt thereof as described in claim 17, followed by contacting it with a pharmaceutically acceptable carrier, diluent and/or excipient.