WO2004005269A1 - Method for producing substituted thiazol-2-yl methyl esters - Google Patents

Abstract

The invention relates to a novel method for producing substituted thiazol-2-yl methyl esters of general formula (II) by means of a multi-component reaction of compounds of formulae (III), (IV) and (V). Said compounds are of particular interest for the synthesis of tubulysins and tubulysin derivatives.

Description

 Process for the preparation of substituted thiazol-2-ylmethyl esters

The present invention relates to a new process for the preparation of substituted thiazol-2-ylmethyl esters via a multicomponent reaction. These compounds are of particular interest in the synthesis of tubulysins and tubulysin derivatives.

Thiazol-2-methyl esters are found in numerous biologically active natural products as well as synthetic derivatives such as. B. Lyngbyabellin A and B, tubulysins, thiostreptones, myxothiazoles, archazolid A, tallysomycin, bleomycin, dysidenin, dolabellin and synthetic epothilone derivatives (Yokokawa et al. Tetrahedron et al. 2001, 42, 4171-4174; Konishi et al Antibiot 1977, 30, 789-805; Sone et al. J. Org. Chem. 1995, 60, 4774-4781; Kazlauskas et al. Tetrahedron Lett. 1977, 36, 3183-3186) and therefore is simpler and more efficient Access to this class of substances is particularly important in the synthesis of active substances.

The object of the present invention was in particular to provide a new one-pot process for the preparation of these compounds, which takes place in a multi-component reaction. Since multicomponent reactions are very variable, they are particularly suitable for the synthesis of substance libraries to find lead structures in the pharmaceutical industry (A. Dömling, I. Ugi, Angew. Chem. 2000, 112, 3300-3344). Another object of the present invention was to use this method to provide an efficient synthesis of the tubulysin class of compounds.

The Tubulysins were first developed by the Höfle and

Reichenbach (GBF Braunschweig) from a culture broth from

Strains of the Myxobacterium Archangium gephyra isolated

(Sasse et al. J. Antibiot. 2000, 53, 879-885; W09813375;

DE10008089). These compounds have an extremely high cytotoxic activity against mammalian cell lines with IC ₅₀ values in the picomolar range and are therefore of great interest in cancer research. Tubulysins (I) are tetrapeptides that contain three unusual amino acids, making their synthesis a challenge for organic synthetic chemistry.

R ¹ = H, CH ₂ 0C (O) CH ₂ CH (CH ₃ ) ₂ , CH ₂ OC (0) CH ₂ CH ₂ CH ₃ , CH ₂ 0H, CH ₂ OC (0) CH ₃ , CH ₂ OC ( 0) CH ₂ CH ₃ , CH ₂ OC (O) CH = C (CH ₃ ) ₂ ; R ² = H,

OH; R ³ = H, Ac

All definitions of residues in the description and the claims refer to all other identical residues occurring in the description and the claims. The present invention describes a new process for the preparation of thiazol-2-ylmethyl esters of the general formula (II):

worin:

wherein:

R ^{4 is} a hydrogen atom, an alkyl, alkenyl, alkynyl, heteroalkyl, aryl, heteroaryl, cycloalkyl, alkylcycloalkyl, heteroalkylcycloalkyl, heterocycloalkyl, aralkyl or a heteroaralkyl radical or a group of the formula COO -L-Pol is where L is a linker and Pol is a polymeric support;

R ^{5 is} a hydrogen atom, an alkyl, alkenyl, alkynyl, heteroalkyl, aryl, heteroaryl, cycloalkyl, alkylcycloalkyl, heteroalkylcycloalkyl, heterocycloalkyl, aralkyl or a heteroaralkyl radical;

R ^{6 is} a hydrogen atom, an alkyl, alkenyl, alkynyl, heteroalkyl, aryl, heteroaryl, cycloalkyl, alkylcycloalkyl, heteroalkylcycloalkyl, heterocycloalkyl, aralkyl or a heteroaralkyl radical;

R ^{7 is} a hydrogen atom, an alkyl, alkenyl, alkynyl, heteroalkyl, aryl, heteroaryl, cycloalkyl, alkylcycloalkyl, heteroalkylcycloalkyl, heterocycloalkyl, aralkyl or a heteroaralkyl radical and R ^{8 is} a hydrogen atom, an alkyl, alkenyl, alkynyl, heteroalkyl, aryl, heteroaryl, cycloalkyl, alkylcycloalkyl, heteroalkylcycloalkyl, heterocycloalkyl, aralkyl or a heteroaralkyl radical.

The term alkyl or alk refers to a saturated, straight-chain or branched hydrocarbon group which has 1 to 20 carbon atoms, preferably 1 to 12 carbon atoms, particularly preferably 1 to 6 carbon atoms, e.g. the methyl, ethyl, propyl, isopropyl, isobutyl, tert-butyl, n-hexyl, 2, 2-dimethylbutyl or n-octyl group.

The terms alkenyl and alkynyl refer to at least partially unsaturated, straight-chain or branched hydrocarbon groups, the 2 to 20

Have carbon atoms, preferably 2 to 12 carbon atoms, particularly preferably 2 to 6 carbon atoms, e.g.

B. the ethenyl, allyl, acetylenyl, propargyl, isoprenyl or hex-2-enyl group. Alkenyl groups preferably have one or two (particularly preferably one) double bonds or

Alkynyl groups one or two (particularly preferably one)

Triple bonds.

Furthermore, the terms alkyl, alkenyl and alkynyl refer to groups in which one or more hydrogen atoms have been replaced by a halogen atom (preferably F or CD, such as the 2, 2, 2-trichloroethyl or the trifluoromethyl group).

The term heteroalkyl refers to an alkyl, an alkenyl or an alkynyl group in which one or more (preferably 1, 2 or 3) carbon atoms are replaced by an oxygen, nitrogen, phosphorus, boron, selenium, silicon or sulfur atom (preferably oxygen, sulfur or nitrogen). The term heteroalkyl also refers to a carboxylic acid group or a group derived from a carboxylic acid, such as, for. B. acyl (alkyl-C0-), acylalkyl, alkoxycarbonyl, acyloxy, acyloxyalkyl, carboxyalkylamide or alkoxycarbonyloxy.

Examples of heteroalkyl groups are groups of the formulas R ^ OY * -, _R ^a _ _s _ _γ ^a _ _# R ^a -N (R ^b ) -Y ^a -, R ^a -CO-Y ^a -, R-0-CO- Y ^a - R ^a -CO-0-Y ^a -, R ^a -CO-N (R ^b ) -Y ^a -, R ^a -N (R ^b ) -CO-Y ^a -

R ^a -0-CO-N (R ^b ) -Y ^a -, R ^a -N (R ^b ) -CO-0-Y ^a -, R ^a -N (R ^b ) -CO-N (R ^c ) -Y ^a - R ^a -0-CO-0-Y ^a -, R ^a -N (R ^b ) -C (= NR ^d ) -N (R ^C ) -Y ^a -, R ^a -CS-Y ^a - R ^a -0-CS-Y ^a -, R ^a -CS-0-Y ^a -, R ^a -CS-N (R ^b ) -Y ^a -, R ^a -N (R ^b ) -CS-Y ^a - R ^a -0-CS-N (R ^b ) -Y ^a -, R ^a -N (R ^b ) -CS-0-Y ^a -, R ^a -N (R ^b ) -CS-N (R ^c ) -Y ^a - R ^a -0-CS-0-Y ^a -, R ^a -S-CO-Y ^a -, R ^a -CO-SY ^a -, R ^a -S-CO-N (R ^b ) -Y ^a - R ^a -N (R ^b ) -C0-SY ^a -, R ^a -S-CO-0-Y ^a -, R ^a -0-CO-SY ^a -, R ^a -S-CO -SY ^a - R ^a -S-CS-Y ^a -, R ^a -CS-SY ^a -, R ^a -S-CS-N (R ^b ) -Y ^a -, RN (R ^b ) -CS-SY ^a - R ^a -S-CS-0-Y ^a -, R ^a -0-CS-SY ^a -, where R ^{a is} a hydrogen atom, a dC ₆ alkyl, a C ₂ -C ₆ alkenyl or a C ₂ -C ₆ alkynyl group; R ^{b represents} a hydrogen atom, a Cx-Ce-alkyl, a C ₂ -C ₆ alkenyl or a C ₂ -C ₃ alkynyl group; R ^{c is} a hydrogen atom, a -C ₆ alkyl, a CC ₆ alkenyl or a C ₂ -C ₆ alkynyl group; R ^d is a hydrogen atom, a Cι-C ₆ - alkyl, C ₂ -C ₆ alkenyl or a C ₂ -C ₆ alkynyl group and Y ^a is a direct bond, a _C]. Is -C ₆ alkylene, a C ₂ -C ₆ alkenylene or a C ₂ -C ₆ alkynylene group, each heteroalkyl group containing at least one carbon atom and one or more hydrogen atoms can be replaced by fluorine or chlorine atoms. Specific examples of heteroalkyl groups are methoxy, trifluoromethoxy, ethoxy, n-propyloxy, iso-propyloxy, tert-butyloxy, methoxymethyl, ethoxymethyl, methoxyethyl, methylamino, ethylamino, diethylamino, diethylamino, iso-propylethylamino, methylaminomethyl, ethylaminomethyl, diisopropylaminoethyl, enol ether, dimethylaminoethyl, dimethylaminoethyl, dimethylaminoethyl , Propionyl, butyryloxy, acetyloxy, methoxycarbonyl, ethoxycarbonyl, N-ethyl-N-methylcarbamoyl or N-methylcarbamoyl. Further examples of heteroalkyl groups are nitrile, isonitrile, cyanate, thiocyanate, isocyanate, isothiocyanate and alkyl nitrile groups.

The term cycloalkyl refers to a saturated or partially unsaturated (e.g. cycloalkenyl) cyclic group which has one or more rings (preferably 1 or 2) which have a total of 3 to 14 ring carbon atoms, preferably 3 to 10 (especially 3 , 4, 5, 6 or 7) contain ring carbon atoms. The term cycloalkyl also refers to groups in which one or more hydrogen atoms have been replaced by fluorine, chlorine, bromine or iodine atoms or OH, = 0, SH, = S, NH ₂ , = NH or NO ₂ groups so z. B. cyclic ketones such. B. cyclohexanone, 2-cyclohexenone or cyclopentanone. Further specific examples of cycloalkyl groups are the cyclopropyl, cyclobutyl, cyclopentyl, spiro [4,5] decanyl, norborny, cyclohexyl, cyclopentenyl, cyclohexadienyl, decalinyl, cubanyl, bicyclo [4.3.0] nonyl -, tetralin, cyclopentylcyclohexyl, fluorocyclohexyl or the cyclohex-2-enyl group.

The term heterocycloalkyl refers to a cycloalkyl group as defined above in which one or more (preferably 1, 2 or 3) ring carbon atoms are represented by one Oxygen, nitrogen, silicon, selenium, phosphorus or sulfur atom (preferably oxygen, sulfur or nitrogen) are replaced. A heterocycloalkyl group preferably has 1 or 2 rings with 3 to 10 (in particular 3, 4, 5, 6 or 7) ring atoms. The term heterocycloalkyl also relates to groups in which one or more hydrogen atoms have been replaced by fluorine, chlorine, bromine or iodine atoms or OH, = 0, SH, = S, NH ₂ , = NH or NO ₂ groups , Examples are the piperidyl, morpholinyl, urotropinyl, pyrrolidinyl, tetrahydrothiophenyl, tetrahydropyranyl, tetrahydrofuryl, oxacyclopropyl, azacyclopropyl or 2-pyrazolinyl group as well as lactams, lactones, cyclic imides and cyclic anhydrides.

The term alkylcycloalkyl refers to groups which, in accordance with the above definitions, contain both cycloalkyl and also alkyl, alkenyl or alkynyl groups, e.g. B. alkylcycloalkyl, alkylcycloalkenyl, alkenylcycloalkyl and alkynylcycloalkyl groups. An alkylcycloalkyl group preferably contains a cycloalkyl group which has one or two ring systems which contain a total of 3 to 10 (in particular 3, 4, 5, 6 or 7) ring carbon atoms and one or two alkyl, alkenyl or alkynyl groups with 1 or 2 up to 6 carbon atoms.

The term heteroalkylcycloalkyl refers to alkylcycloalkyl groups, as defined above, in which one or more (preferably 1, 2 or 3) carbon atoms are represented by an oxygen, nitrogen, silicon, selenium, phosphorus or sulfur atom (preferably oxygen, sulfur or Nitrogen) are replaced. Preferably has one Heteroalkylcycloalkyl group 1 or 2 ring systems with 3 to 10 (in particular 3, 4, 5, 6 or 7) ring atoms and one or two alkyl, alkenyl, alkynyl or heteroalkyl groups with 1 or 2 to 6 carbon atoms. Examples of such groups are alkyl heterocycloalkyl, alkyl heterocycloalkenyl, alkenyl heterocycloalkyl, alkynyl heterocycloalkyl, heteroalkylcycloalkyl, heteroalkyl heterocycloalkyl and heteroalkyl heterocylcloalkenyl, the cyclic groups being saturated or mono-, di- or trisaturated.

The term aryl or Ar refers to an aromatic group which has one or more rings which contain a total of 6 to 14 ring carbon atoms, preferably 6 to 10 (in particular 6) ring carbon atoms. The term aryl (or Ar) also refers to groups in which one or more hydrogen atoms have been replaced by fluorine, chlorine, bromine or iodine atoms or OH, SH, NH ₂ or NO ₂ groups. Examples are the phenyl, naphthyl, biphenyl, 2-fluorophenyl, anilinyl, 3-nitrophenyl or 4-hydroxyphenyl group.

The term heteroaryl refers to an aromatic group which has one or more rings which contain a total of 5 to 14 ring atoms, preferably 5 to 10 (in particular 5 or 6) ring atoms and one or more (preferably 1, 2, 3 or 4 ) Contain oxygen, nitrogen, phosphorus or sulfur ring atoms (preferably O, S or N). The expression heteroaryl also refers to groups in which one or more hydrogen atoms have been replaced by fluorine, chlorine, bromine or iodine atoms or OH, SH, NH ₂ or NO ₂ groups. examples are 4-pyridyl, 2-imidazolyl, 3-phenylpyrrolyl, thiazolyl, oxazolyl, triazolyl, tetrazolyl, isoxazolyl, indazolyl, indolyl, benzimidazolyl, pyridazinyl, quinolinyl, purinyl, carbazolyl , Acridinyl, pyrimidyl, 2, 3 "bifuryl, 3-pyrazolyl and isoquinolinyl groups.

The term aralkyl refers to groups which, according to the above definitions, contain both aryl and also alkyl, alkenyl, alkynyl and / or cycloalkyl groups, such as, for. B. arylalkyl, arylalkenyl, arylalkynyl, arylcycloalkyl, arylcycloalkenyl, alkylarylcycloalkyl and alkyl arylcycloalkenyl groups. Specific examples of aralkyls are toluene, xylene, mesitylene, styrene, benzyl chloride, o-fluorotoluene, 1H-indene, tetralin, dihydronaphthalenes, indanone, phenylcyclopentyl, cumene, cyclo-hexylphenyl, fluorene and indane. An aralkyl group preferably contains one or two aromatic ring systems (1 or 2 rings) with a total of 6 to 10 ring carbon atoms and one or two alkyl, alkenyl and / or alkynyl groups with 1 or 2 to 6 carbon atoms and / or a cycloalkyl group with 5 or 6 ring carbon atoms.

The term heteroaralkyl refers to an aralkyl group as defined above in which one or more (preferably 1, 2, 3 or 4) carbon atoms are represented by an oxygen, nitrogen, silicon, selenium, phosphorus, boron or sulfur atom (preferably oxygen , Sulfur or nitrogen) are replaced, ie on groups which, according to the above definitions, are both aryl or heteroaryl and also alkyl, alkenyl, alkynyl and / or heteroalkyl and / or cycloalkyl and / or heterocycloalkyl groups contain. Preferably contains one Heteroaralkyl group one or two aromatic ring systems (1 or 2 rings) with a total of 5 or 6 to 10 ring carbon atoms and one or two alkyl, alkenyl and / or alkynyl groups with 1 or 2 to 6 carbon atoms and / or a cycloalkyl group with 5 or 6 ring carbon atoms, 1, 2, 3 or 4 of these carbon atoms being replaced by oxygen, sulfur or nitrogen atoms.

Examples are aryl heteroalkyl, aryl heterocycloalkyl, aryl heterocycloalkenyl, aryl alkyl heterocycloalkyl, aryl alkenyl heterocycloalkyl, arylalkynyl heterocyclo alkyl, aryl alkyl heterocycloalkenyl, heteroaryl alkyl, hetero aryl hetero aryl hetero aryl , Heteroarylhetero- cycloalkyl-, Heteroarylheterocycloalkenyl-, Heteroarylal- kylcycloalkyl-, Heteroarylalkylheterocycloalkenyl-, arylheteroalkylcycloalkyl- hetero-, Heteroarylheteroalkylcycloalke- nyl- and Heteroarylheteroalkylheterocycloalkyl groups, WO at the cyclic groups being saturated or mono-, di- or tri-unsaturated. Specific examples are the tetrahydroisoquinolinyl, benzoyl, 2- or 3-ethylindolyl, 4-methylpyridino, 2-, 3- or 4-methoxyphenyl, 4-ethoxyphenyl, 2-, 3- or 4-carboxyphenylalkyl group.

The terms cycloalkyl, heterocycloalkyl, alkylcycloalkyl, heteroalkylcycloalkyl, aryl, heteroaryl, aralkyl and heteroaralkyl also refer to groups in which one or more hydrogen atoms of such groups are represented by fluorine, chlorine, bromine or iodine atoms or OH, = 0, SH, = S, NH ₂ , = NH or N0 ₂ groups are replaced. The term "optionally substituted" refers to groups in which one or more hydrogen atoms are replaced by fluorine, chlorine, bromine or iodine atoms or OH, = 0, SH, = S, NH ₂ , = NH or NO ₂ groups are. This expression also relates to groups which exclusively or additionally with unsubstituted -CC ₆ alkyl, C ₂ -C ₆ alkenyl, C ₂ -C ₆ alkynyl, -C-C ₆ heteroalkyl, C ₃ -Cι ₀ cycloalkyl -, C ₂ -C ₉ heterocycloalkyl, C ₆ -Cι ₀ aryl, -C-C ₉ heteroaryl, C ₇ -Cι ₂ aralkyl or C ₂ -Cn heteroaralkyl groups are substituted.

Compounds of formula (I) can contain one or more centers of chirality due to their substitution. The present invention therefore encompasses all pure enantiomers and all pure diastereomers, as well as their mixtures in any mixing ratio. Furthermore, the present invention also includes all cis / trans isomers of the compounds of the general formula (I) and mixtures thereof. The present invention further encompasses all tautomeric forms of the compounds of the formula (I).

The term linker refers to a group that is suitable for connecting molecules to a polymeric support. A linker can be an alkyl, heteroalkyl, aryl, heteroaryl, cycloalkyl, heterocycloalkyl, aralkyl or a heteroaralkyl group. Examples of linkers are found in P. Seneci, Solid-Phase Synthesis and Combinatorial Technologies, John Wiley & Sons, New York, 2000; D. Obrecht and JM Villalgordo, Solid-Supported Combinatorial and Parallel Synthesis of Small-Molecular-Weight Compound Libraries, Tetrahedron Organic-Chemistry Series Volume 17, Elsevier Science Ltd, Oxford, 1998 and in FZ Dörwald, Organic Synthesis on Solid Phase, Wiley-VCH, Weinheim, 2000, which examples are included here with reference. Examples include the trityl linker, the Wang linker, the SASRIN ™ linker, the Rink acid linker, the benzhydryl alcohol linker, the HMBA linker and polymeric benzyl halide (linker of the Merrifield resin) and the PAM linker.

The term polymeric carrier refers to a polymer that has been modified for organic solid phase synthesis. Examples of polymeric supports are described in P. Seneci, Solid-Phase Synthesis and Combinatorial Technologies, John Wiley & Sons, New York, 2000; D. Obrecht and JM Villalgordo, Solid-Supported Combinatorial and parallel Synthesis of Small- Molecular-Weight Compound Libraries, Tetrahedron Organic- Chemistry Series Volume 17, Elsevier Science Ltd, Oxford, 1998 and in FZ Dörwald, Organic Synthesis on Solid Phase, Wiley -VCH, Weinheim, 2000, which examples are included here with reference. A distinction is made between soluble and insoluble polymeric carriers. Examples of soluble polymeric carriers are the polyethylene glycols (PEG). Examples of insoluble polymeric supports are polymers based on polystyrene (crosslinked with divinylbenzene) such as. As the Merrifield resin, bromo (4- methoxyphenyDmethyl Polystyrrol, 4- (bromomethyl) phenoxy ethyl Polystyrrol, the 2-Clorotrityl resin tentacle polymers such as Tentagel ^®, silica gel, controlled pore glass (CPG), cellulose, copolymers and gold.Polymeric carriers, as well as polymeric carriers modified by linkers, are available from a number of companies such as Calbiochem-Novabiochem AG, Laufelfingen, Switzerland, Bachern AG, Bubendorf, Switzerland, Rapp Polymer GmbH, Tübingen, Germany, Advanced ChemTech . Louisville, KY, USA and Shearwater Corporation, Huntsville, Alabama, USA are commercially available.

Protecting groups are known to the expert and z. B. in P. J. Kocienski, Protecting Groups, Georg Thieme Verlag, Stuttgart, 1994 and in T. W. Greene, P. G. M. Wuts, Protective Groups in Organic Synthesis, John Wiley & Sons, New York, 1999, which examples are incorporated herein by reference. Common amino protecting groups are e.g. B. t-Butyloxycarbonyl- (Boc), Benzyloxycarbonyl- (Cbz, Z), Benzyl- (Bn), Benzoyl- (Bz), Fluorenylmethyloxycarbonyl- (Fmoc), Allyloxycarbonyl- (Alloc), Trichlorethyloxycarbonyl- (Troc), Acetyl- or trifluoroacetyl groups.

The compounds according to the invention can be prepared by reacting compounds of the formulas (III), (IV) and (V)

ll) (IV) (V)

ll) (IV) (V)

where X is a leaving group such. B. F, Cl, Br, I, NR 9 ^b τR-, 10 OR ¹¹ or SO _n R ¹² , wherein R ⁹ , R ¹⁰ , R ¹¹ and R ^{12 are} independently a hydrogen atom, an alkyl, heteroalkyl, aryl - Aralkyl, cycloalkyl, cycloaralkyl, heterocycloalkyl, heteroaralkyl, or a heteroaryl radical and n = 0, 1, 2 or 3. By suitable choice of the reaction conditions (e.g. addition of ammonia in methanol), compounds of the formula (Ha) can be prepared directly:

According to a preferred embodiment, R ^{4 is} a group of the formula COOR ¹³ , a pyridyl group or a group of the formula S0 ₂ aryl, where R ^{13 is} an alkyl group or a group of the formula -L-Pol where L is a linker and Pol is a polymeric carrier ,

R ⁴ is particularly preferably a group of the formula COOMe, COOEt or COO'Εu.

According to a further preferred embodiment, R ^{5 is} a hydrogen atom.

R ⁶ is furthermore preferably a hydrogen atom.

Further preferably R ⁷ is a Cι-C ₆ alkyl, C ₂ -C ₆ - alkenyl, C ₂ -C ₆ alkynyl, _Cι-C5 heteroalkyl, C ₆ - or Cι ₀ - aryl , C ₅ -C ₉ heteroaryl-, C ₃ -Cι ₀ cycloalkyl-, C ₄ -C _n - alkylcycloalkyl-, C ₃ -Cι ₀ heteroalkylcycloalkyl-, C ₂ -C ₉ - heterocycloalkyl-, C ₇ -C ₁₂ aralkyl or a C ₅ -C ₂ heteroaralkylres,

wherein the radical R ⁷ in the beta position relative to the thiazole ring preferably has no hydrogen atom or hetero atom. X is more preferably a group of the formula NMe ₂ .

The reactions in an aprotic solvent such as. B. tetrahydrofuran (THF), dioxane, diethyl ether, acetonitrile or methylene chloride, with ethers such as. B. THF are particularly preferred.

The compounds (III), (IV) and (V) are preferably used in equimolar amounts.

Furthermore, the reactions are preferably carried out under an inert gas atmosphere (for example N ₂ , Ar).

The preferred reaction temperatures are in the range from -100 ° C. to 100 ° C., reaction temperatures from -80 ° C. to 60 ° C. being particularly preferred (temperatures from -25 ° C. to 25 ° C. are particularly preferred). The reaction is optionally carried out in a microwave reactor.

Optionally, the addition of a Lewis acid such as. B. boron trifluoride etherate, trimethyl aluminum, lithium chloride, aluminum trichloride, zinc chloride (ZnCl ₃ ), ytterbium triflate, magnesium triflate, magnesium bromide, zirconium chloride (ZrCl ₄ ), titanium (IV) chloride, zinc triflate (Zn (OTf) ₂ ), scandium triflate (Sc (triflate) ) ₃ ), hafnium triflate (Hf (OTf) ₄ ) or tin tetrachloride may be preferred.

More preferably, compound (III) is first dissolved in the solvent with the Lewis acid and then (preferably after 5 to 30 minutes) compounds (IV) and (V) are added. A key compound in the synthesis of some of the tubulysin derivatives described above is an amino acid derivative of the general formula (VI):

This compound can be synthesized in a simple manner using the process described here by reacting compounds of the formulas (IV), (VII) and (VIII)

where PG is an amino protecting group and R ^{14 is} a hydrogen atom, an alkyl or a heteroalkyl radical. This method is also encompassed by the present invention.

PG is preferably a Boc group, R is a hydrogen atom and

R 13 is a methyl, an ethyl or a tert-butyl group. The synthesis of compounds of the formulas (III) or (VIII) is, for. B. in Schöllkopf et al. Liebigs Ann. Chem. 1979, 1444-1446.

Compounds of formula (IV) are commercially available.

α-Aminothioacids of the formula (V) z. B. after the in Wieland et al. Chem. Ber. 1958, 91, 2305-2308 described methods are prepared and are, for. Some also commercially available.

Compounds of formula (VII) z. B. via an α-aminoalkylation from isobutyraldehyde, ammonium acetate or a primary amine or its hydrochloride and malonic acid. The resulting ß-amino acid is then optionally N-alkylated (e.g. by reductive amination) and then provided with a protective group (e.g. t-butyloxycarbonyl, Boc). The acid group is then converted into the aldehyde according to standard regulations (see, for example, R.C. Larock, Comprehensive Organic Transformations, VCH Publishers, New York, 1989). Alternatively, the β-amino acid can also be produced from valine via an Arndt-Eistert reaction.

According to a further preferred embodiment, an isoleucine derivative of the formula (IX) is used as the thiocarboxylic acid (general formula IV),

where PG ^'is an amino protecting group (preferably Boc). In this embodiment, compounds of the formula (X)

which after splitting off the protective groups PG and PG 'can be converted by rearrangement in compound (XI).

The synthesis of tubulysins of the formula (I) can be carried out using the following steps starting from compound (XI): Coupling with N-pipecolic acid to compound (XII)

Deprotection of the carboxylic acid to a compound (XII) with R ¹³ = H.

Coupling with the amino acid derivative described in DE 10008089 and subsequent deprotection of the carboxylic acid to give compound (XIII) (R ² = H or OH)

Conversion of compound (XIII) to compound (XIV) (e.g. with paraformaldehyde in the presence of an acid) and subsequent opening of the six-membered ring with a carboxylic acid anion (e.g. (CH ₃ ) ₂ CHCH ₂ COO ^" , CH ₃ CH ₂ CH ₂ COO ^" , CH ₃ COO ^" , CH ₃ CH ₂ COO ^" , (CH ₃ ) ₂ C = CHCOO ^" ) to a compound of the formula (I) with R ¹ = CH ₂ OC (0) R ¹⁵ , where R ^{15 is} an alkyl group.

Examples

General working instructions 1:

1 mmol of the carbonyl compound (IV) is abs. In 3 ml. THF dissolved and 1 mmol of boron trifluoride etherate added. After 10 min, 1 mmol of the isonitrile (III) and 1 mmol of the thiocarboxylic acid (V) are added to this mixture, and the mixture is stirred for 72 h. For working up, water is added and, if appropriate, filtered off through Celite. The mixture is then evaporated to dryness, taken up in ethyl acetate and extracted twice with water. After the organic phase has been dried over sodium sulfate, the mixture is evaporated to dryness. The residue is purified by preparative HPLC (reversed phase C18 phase, eluent methanol + 0.5% acetic acid / water + 0.5% acetic acid).

General procedure 2: 3 mmol of the aldehyde component (IV) are under inert

Conditions (nitrogen atmosphere) dissolved in 6 ml of dry THF and cooled to -18 ° C. Then 3 mmol

(378 μl) boron trifluoride etherate added and stirred for 5 min. 3 mmol (462 mg) isocyanide (III) and 3 mmol thioic acid (V) are added and the reaction mixture a further 30 min at -18 ° C stirred. The mixture is allowed to warm to RT and stirred for a further 18 h.

After 18 h, the reaction is hydrolyzed with 6 ml of water and mixed with 6 ml of ethyl acetate. The aqueous phase is separated off and the organic phase is washed 3 times with 3 ml of saturated sodium hydrogen carbonate solution, 3 times with 3 ml of 5% citric acid and 2 times with 3 ml of saturated sodium chloride solution. The ethyl acetate phase is dried over sodium sulfate and evaporated. The raw product is purified by means of chromatotrography.

example 1

C ₁₄ Η ₁₂ N ₂ 0 ₆ S (336. 3255) MS (ESI): 337 [M + H]

Example 2

C ₁₆ Hι ₇ N0 ₄ S (319.3822) MS (ESI): 320 [M + H]

Example 3

Cι ₂ H ₁₇ N0 ₄ S (271.3376) MS (ESI): 272 [M + H]

Example 4

C ₁₄ H ₁₉ N0 ₄ S (297.3758) MS (ESI): 298 [M + H]

Example 5

C ₁₃ H ₁₉ N0 ₄ S (285.3647) MS (ESI): 286 [M + H] Example 6;

Cι ₂ H ₁₇ N0 ₄ S (271.3376) MS (ESI): 272 [M + H]

Example 7

CnH ₁₃ N0 ₄ S (255.2946) MS (ESI): 256 [M + H]

Example 8

C ₁₄ H ₁₉ N0 ₄ S (297.3758) MS (ESI): 298 [M + H] Example 9

C ₁₂ Hι ₄ F ₃ N0 ₄ S (325.3089) MS (ESI): 326 [M + H]

Example 10

C ₁₅ H ₁₅ N0 ₅ S (321.3545) MS (ESI): 322 [M + H]

Example 11:

C₁₄H₁₂BrN0₄S (370.2240) MS (ESI) : 371 [M+H]

C ₁₄ H ₁₂ BrN0 ₄ S (370.2240) MS (ESI): 371 [M + H]

Example 12:

C ₁₆ Hι ₇ N0 ₄ S (319.3822) MS (ESI): 320 [M + H]

Example 13

CnH ₁₅ N0 ₄ S ₂ (289.3745) MS (ESI): 290 [M + H]

Example 14:

C ₁₈ H ₂₈ N ₂ 0 ₆ S (400.4977) MS (ESI): 401 [M + H]

Example 15

Cι ₉ H ₃₀ N ₂ O ₆ S (414.5248) MS (ESI): 415 [M + H]

Example 16:

C ₂₄ H ₃₂ N ₂ 0 ₆ S (476.5964) MS (ESI): 477 [M + H]

Example 17

C ₂₈ H ₄₇ N ₃ 0 ₈ S (585.7661) MS (ESI): 586 [M + H]

Example 18:

The compound from Example 15 (0.1 mmol) is dissolved in 2 ml dichloromethane (DCM) and 0.1 ml trifluoroacetic acid (TFA) and stirred for 1 h at room temperature. The DCM / TFA mixture is then removed in vacuo and the residue is purified by HPLC.

Cι ₄ H ₂₂ N ₂ 0 ₄ S (314.4064) MS (ESI): 315 [M + H]

Example 19:

The compound from Example 16 (0.1 mmol) is dissolved in 2 ml of dichloromethane (DCM) and 0.1 ml of trifluoroacetic acid (TFA) and stirred at room temperature for 1 h. Subsequently the DCM / TFA mixture is removed in vacuo and the residue is purified by HPLC.

Cι ₉ H ₂₄ N ₂ 0 ₄ S (376. 4781) MS (ESI): 377 [M + H]

Example 20:

The compound from Example 17 (0.1 mmol) is dissolved in 2 ml of dichloromethane (DCM) and 0.1 ml of trifluoroacetic acid (TFA) and stirred at room temperature for 1 h. The DCM / TFA mixture is then removed in vacuo and the residue is purified by HPLC.

C ₁₈ H ₃ 1 ₃ O ₄ S (385.5295) MS (ESI): 386 [M + H]

Example 21

Cι ₆ Hι ₇ N0 ₄ S (319.38) MS (ESI): 342 [M + Na]

Example 22

CnH ₁₅ N0 ₄ S (257.31) MS (ESI): 280 [M + Na]

Example 23

C ₁₂ H ₁₇ N0 ₄ S (271.33) MS (ESI): 272 [M + H], 294 [M + Na]

Example 24

C ₁₈ H ₂₈ N ₂ 0 ₆ S (400.50) MS (ESI): 401 [M + H], 423 [M + Na]

Claims

claims 1. Process for the preparation of compounds of the general formula (II):

wherein: R ^{4 is} a hydrogen atom, an alkyl, alkenyl, alkynyl, heteroalkyl, aryl, heteroaryl, cycloalkyl, alkylcycloalkyl, heteroalkylcycloalkyl, heterocycloalkyl, aralkyl or a heteroaralkyl radical or a group of the formula COO-L -Pol is where L is a linker and Pol is a polymeric support; R ^{5 is} a hydrogen atom, an alkyl, alkenyl, alkynyl, heteroalkyl, aryl, heteroaryl, cycloalkyl, alkylcycloalkyl, heteroalkylcycloalkyl, heterocycloalkyl, aralkyl or a heteroaralkyl radical; R ^{6 is} a hydrogen atom, an alkyl, alkenyl, alkynyl, heteroalkyl, aryl, heteroaryl, cycloalkyl, alkylcycloalkyl, heteroalkylcycloalkyl, heterocycloalkyl, aralkyl or a heteroaralkyl radical; R ^{7 is} a hydrogen atom, an alkyl, alkenyl, alkynyl, heteroalkyl, aryl, heteroaryl, cycloalkyl, alkylcycloalkyl, heteroalkylcycloalkyl, heterocycloalkyl, aralkyl or a heteroaralkyl radical and R ^{8 is} a hydrogen atom, an alkyl, alkenyl, alkynyl, heteroalkyl, aryl, heteroaryl, cycloalkyl, alkylcycloalkyl, heteroalkylcycloalkyl, heterocycloalkyl, aralkyl or a heteroaralkyl radical, characterized in that compounds of the formulas (III), (IV) and (V) are reacted with one another,

(III) (IV) (V) where X is a leaving group such. B. F, Cl, Br, I, NR ⁹ R ¹⁰ , OR ¹¹ or SO _n R ¹² , where R ⁹ , R ¹⁰ , R ¹¹ and R ^{12 are} independently a hydrogen atom, an alkyl, heteroalkyl, aryl, Aralkyl, cycloalkyl, cycloaralkyl, heterocycloalkyl, heteroaralkyl, or a heteroaryl radical and n = 0, 1, 2 or 3. 2. The method according to claim 1, wherein R ^{4 is} a group of the formula COOMe, COOEt or COO ^t Bu. 3. The method according to any one of claims 1 or 2, wherein R ^{5 is} a hydrogen atom. 4. The method according to any one of claims 1 to 3, wherein X is a group of the formula NMe ₂ . 5. The method according to any one of claims 1 to 4, wherein R ^{6 is} a hydrogen atom. 6. The method of claim 5, wherein R ^{7 is} a group of the formula CH ₂ CH (CH (CH ₃ ) ₂ ) NR ¹⁴ PG, wherein PG is an amino protecting group and R ^{14 is} a hydrogen atom, an alkyl or a heteroalkyl group. 7. The method of claim 6, wherein R ^{14 is} a hydrogen atom. 8. The method according to any one of claims 1 to 7, wherein R ^{8 is} a methyl group. 9. The method according to any one of claims 1 to 7, wherein R ^{8 is} a group of the formula CH (CH (CH ₃ ) CH ₂ CH ₃ ) NHPG ', wherein PG' is an amino protecting group.