Claims for Patent: 5,847,170

Summary for Patent: 5,847,170

Title:	Taxoids, their preparation and pharmaceutical compositions containing them
Abstract:	New taxoids of general formula (I): ##STR1## their preparation and pharmaceutical compositions containing them, and the new products of general formula (I) in which Z represents a radical of general formula (II): ##STR2## display noteworthy antitumour and antileukaemic properties.
Inventor(s):	Bouchard; Herve (Ivry-sur-Seine, FR), Bourzat; Jean-Dominique (Vincennes, FR), Commer.cedilla.on; Alain (Vitry-sur-Seine, FR)
Assignee:	Rhone-Poulenc Rorer, S.A. (Antony Cedex, FR)
Application Number:	08/622,011
Patent Litigation and PTAB cases:	See patent lawsuits and PTAB cases for patent 5,847,170
Patent Claims:	1. 4.alph a.-Acetoxy-2.alpha.-benzoyloxy-5.beta.,20-epoxy-1.beta.-hydroxy-7.beta.,10. beta.-dimethoxy-9-oxo-11-taxen-13.alpha.-yl(2R,3S)-3-tert-butoxycarbonylami no-2-hydroxy-3-phenylpropionate. 2. A pharmaceutical composition comprising at least the product according to claim 1 in combination with one or more pharmaceutically acceptable diluents or adjuvants and optionally one or more compatible and pharmacologically active compounds. 3. A method comprising the step of etherifying selectively at position 7 a compound of the formula (XIV): ##STR23## wherein R.sub.4 represents an alkoxy radical containing 1 to 6 carbon atoms in an unbranched or branched chain, with a compound of the formula (XV): wherein R'.sub.5 represents a radical such that R'.sub.5 --O represents an alkoxy radical containing 1 to 6 carbon atoms in an unbranched or branched chain and X.sub.2 represents a reactive ester residue or a halogen atom, to produce a compound of the formula (I): ##STR24## wherein Z is hydrogen, R.sub.4 is as defined above, and R.sub.5 is identical to R'.sub.5 as defined above. 4. A method comprising the step of reacting a product of the formula (XV): wherein R'.sub.5 represents a radical such that R'.sub.5 --O represents an alkoxy radical containing 1 to 6 carbon atoms in an unbranched or branched chain, and X.sub.2 represents a reactive ester residue or a halogen atom, with a compound of the formula (XIX): ##STR25## wherein R.sub.1 represents a benzoyl radical optionally substituted with one or more identical or different atoms or radicals selected from halogen atoms, alkyl radicals containing 1 to 4 carbon atoms, alkoxy radicals containing 1 to 4 carbon atoms, and trifluoromethyl radicals, a thenoyl radical, a furoyl radical, or a radical R.sub.2 --O--CO-- in which R.sub.2 represents: an alkyl radical containing 1 to 8 carbon atoms, an alkenyl radical containing 2 to 8 carbon atoms, an alkynyl radical containing 3 to 8 carbon atoms, a cycloalkyl radical containing 3 to 6 carbon atoms, a cycloalkenyl radical containing 4 to 6 carbon atoms or a bicycloalkyl radical containing 7 to 10 carbon atoms, these radicals being optionally substituted with one or more substituents selected from halogen atoms; hydroxyl radicals; alkoxy radicals containing 1 to 4 carbon atoms; dialkylamino radicals in which each alkyl portion contains 1 to 4 carbon atoms; piperidino radicals; morpholino radicals; 1-piperazinyl radicals optionally substituted at position 4 with an alkyl radical containing 1 to 4 carbon atoms or with a phenylalkyl radical in which the alkyl portion contains 1 to 4 carbon atoms; cycloalkyl radicals containing 3 to 6 carbon atoms; cycloalkenyl radicals containing 4 to 6 carbon atoms; phenyl radicals optionally substituted with one or more atoms or radicals selected from halogen atoms, alkyl radicals containing 1 to 4 carbon atoms and alkoxy radicals containing 1 to 4 carbon atoms; cyano radicals; carboxyl radicals; and alkoxycarbonyl radicals in which the alkyl portion contains 1 to 4 carbon atoms, a phenyl or .alpha.- or .beta.-naphthyl radical optionally substituted with one or more atoms or radicals selected from halogen atoms; alkyl radicals containing 1 to 4 carbon atoms; and alkoxy radicals containing 1 to 4 carbon atoms, a 5-membered aromatic heterocyclic radical, or a saturated heterocyclic radical containing 4 to 6 carbon atoms, optionally substituted with one or more alkyl radicals containing 1 to 4 carbon atoms, R.sub.3 represents an unbranched or branched alkyl radical containing 1 to 8 carbon atoms, an unbranched or branched alkenyl radical containing 2 to 8 carbon atoms, an unbranched or branched alkynyl radical containing 2 to 8 carbon atoms, a cycloalkyl radical containing 3 to 6 carbon atoms, a phenyl or .alpha.- or .beta.-naphthyl radical optionally substituted with one or more atoms or radicals selected from halogen atoms, alkyl, alkenyl, alkynyl, aryl, aralkyl, alkoxy, alkylthio, aryloxy, arylthio, hydroxyl, hydroxyalkyl, mercapto, formyl, acyl, acylamino, aroylamino, alkoxycarbonylamino, amino, alkylamino, dialkylamino, carboxyl, alkoxycarbonyl, carbamoyl, alkylcarbamoyl, dialkylcarbamoyl, cyano, nitro and trifluoromethyl radicals, or a 5-membered aromatic heterocycle containing one or more identical or different hetero atoms selected from nitrogen, oxygen and sulphur atoms and optionally substituted with one or more identical or different substituents selected from halogen atoms, alkyl, aryl, amino, alkylamino, dialkylamino, alkoxycarbonylamino, acyl, arylcarbonyl, cyano, carboxyl, carbamoyl, alkylcarbamoyl, dialkylcarbamoyl and alkoxycarbonyl radicals, with the proviso that, in the substituents of the phenyl, .alpha.- or .beta.-naphthyl and aromatic heterocyclic radicals in the definitions of R.sub.2 and R.sub.3, the alkyl radicals and the alkyl portions of the other radicals contain 1 to 4 carbon atoms, and the alkenyl and alkynyl radicals contain 2 to 8 carbon atoms, and the aryl radicals are phenyl or .alpha.- or .beta.-naphthyl radicals, R.sub.4 represents an alkoxy radical containing 1 to 6 carbon atoms in an unbranched or branched chain either R.sub.6 represents a hydrogen atom and R.sub.7 represents a group protecting the hydroxyl function, or R.sub.6 and R.sub.7 together form a saturated 5- or 6-membered heterocycle, to form a compound of the formula (V): ##STR26## wherein R.sub.5 represents an alkoxy radical containing 1 to 6 carbon atoms in an unbranched or branched chain and R.sub.1, R.sub.3, R.sub.4, R.sub.6, and R.sub.7 are as defined above. 5. A method comprising the step of replacing with hydrogen atom(s) group(s) R.sub.6 and R.sub.7 in a compound of the formula (V): ##STR27## wherein: R.sub.1 represents a benzoyl radical optionally substituted with one or more identical or different atoms or radicals selected from halogen atoms, alkyl radicals containing 1 to 4 carbon atoms, alkoxy radicals containing 1 to 4 carbon atoms, and trifluoromethyl radicals, a thenoyl radical, a furoyl radical, or a radical R.sub.2 --O--CO-- in which R.sub.2 represents: an alkyl radical containing 1 to 8 carbon atoms, an alkenyl radical containing 2 to 8 carbon atoms, an alkynyl radical containing 3 to 8 carbon atoms, a cycloalkyl radical containing 3 to 6 carbon atoms, a cycloalkenyl radical containing 4 to 6 carbon atoms or a bicycloalkyl radical containing 7 to 10 carbon atoms, these radicals being optionally substituted with one or more substituents selected from halogen atoms; hydroxyl radicals; alkoxy radicals containing 1 to 4 carbon atoms; dialkylamino radicals in which each alkyl portion contains 1 to 4 carbon atoms; piperidino radicals; morpholino radicals; 1-piperazinyl radicals optionally substituted at position 4 with an alkyl radical containing 1 to 4 carbon atoms or with a phenylalkyl radical in which the alkyl portion contains 1 to 4 carbon atoms; cycloalkyl radicals containing 3 to 6 carbon atoms; cycloalkenyl radicals containing 4 to 6 carbon atoms; phenyl radicals optionally substituted with one or more atoms or radicals selected from halogen atoms, alkyl radicals containing 1 to 4 carbon atoms and alkoxy radicals containing 1 to 4 carbon atoms; cyano radicals; carboxyl radicals; and alkoxycarbonyl radicals in which the alkyl portion contains 1 to 4 carbon atoms, a phenyl or .alpha.- or .beta.-naphthyl radical optionally substituted with one or more atoms or radicals selected from halogen atoms; alkyl radicals containing 1 to 4 carbon atoms; and alkoxy radicals containing 1 to 4 carbon atoms, a 5-membered aromatic heterocyclic radical, or a saturated heterocyclic radical containing 4 to 6 carbon atoms, optionally substituted with one or more alkyl radicals containing 1 to 4 carbon atoms, R.sub.3 represents an unbranched or branched alkyl radical containing 1 to 8 carbon atoms, an unbranched or branched alkenyl radical containing 2 to 8 carbon atoms, an unbranched or branched alkynyl radical containing 2 to 8 carbon atoms, a cycloalkyl radical containing 3 to 6 carbon atoms, a phenyl or .alpha.- or .beta.-naphthyl radical optionally substituted with one or more atoms or radicals selected from halogen atoms, alkyl, alkenyl, alkynyl, aryl, aralkyl, alkoxy, alkylthio, aryloxy, arylthio, hydroxyl, hydroxyalkyl, mercapto, formyl, acyl, acylamino, aroylamino, alkoxycarbonylamino, amino, alkylamino, dialkylamino, carboxyl, alkoxycarbonyl, carbamoyl, alkylcarbamoyl, dialkylcarbamoyl, cyano, nitro and trifluoromethyl radicals, or a 5-membered aromatic heterocycle containing one or more identical or different hetero atoms selected from nitrogen, oxygen and sulphur atoms and optionally substituted with one or more identical or different substituents selected from halogen atoms, alkyl, aryl, amino, alkylamino, dialkylamino, alkoxycarbonylamino, acyl, arylcarbonyl, cyano, carboxyl, carbamoyl, alkylcarbamoyl, dialkylcarbamoyl and alkoxycarbonyl radicals, with the proviso that, in the substituents of the phenyl, .alpha.- or .beta.-naphthyl and aromatic heterocyclic radicals in the definitions of R.sub.2 and R.sub.3, the alkyl radicals and the alkyl portions of the other radicals contain 1 to 4 carbon atoms, and the alkenyl and alkynyl radicals contain 2 to 8 carbon atoms, and the aryl radicals are phenyl or .alpha.- or .beta.-naphthyl radicals, R.sub.4 represents an alkoxy radical containing 1 to 6 carbon atoms in an unbranched or branched chain R.sub.5 represents an alkoxy radical containing 1 to 6 carbon atoms in an unbranched or branched chain and either R.sub.6 represents a hydrogen atom and R.sub.7 represents a group protecting the hydroxyl function, or R.sub.6 and R.sub.7 together form a saturated 5- or 6-membered heterocycle, by treating the compound of formula (V) with an organic or inorganic acid, optionally in an organic solvent to obtain a compound of the formula (VII): ##STR28## wherein R.sub.3, R.sub.4, and R.sub.5 are as defined above. 6. A process for the preparation of 4.alpha.-acetoxy-2.alpha.-benzoyloxy-5.beta.,20-epoxy-1.beta.-hydroxy-7.be ta.,10.beta.-dimethoxy-9-oxo-11-taxen-13.alpha.-yl (2R,3S)-3-tert-butoxycarbonylamino-2-hydroxy-3-phenylpropionate, said process comprising: converting 4.alpha.-acetoxy-2.alpha.-benzoyloxy-5.beta.,20-epoxy-1.beta.-hydroxy-7.be ta.,10.beta.-bis(methylthiomethoxy)-9-oxo-11-taxen-13.alpha.-yl (2R,4S,5R)-3-tert-butoxycarbonyl-2-(4-methoxyphenyl)-4-phenyl-1,3-oxazolid ine-5-carboxylate to said 4.alpha.-acetoxy-2.alpha.-benzoyloxy-5.beta.,20-epoxy-1.beta.-hydroxy-7.be ta.,10.beta.-dimethoxy-9-oxo-11-taxen-13.alpha.-yl (2R,3S)-3-tert-butoxycarbonylamino-2-hydroxy-3-phenylpropionate. 7. A process for the preparation of 4.alpha.-acetoxy-2.alpha.-benzoyloxy-5.beta.,20-epoxy-1.beta.-hydroxy-7.be ta.,10.beta.-dimethoxy-9-oxo-11-taxen-13.alpha.-yl (2R,3S)-3-tert-butoxycarbonylamino-2-hydroxy-3-phenylpropionate, said process comprising: (a) reacting 4.alpha.-acetoxy-2.alpha.-benzoyloxy-5.beta.,20-epoxy-1.beta.-7.beta.,10.b eta.-trihydroxy-9-oxo-11-taxen-13.alpha.-yl (2R,4S,5R)-3-tert-butoxycarbonyl-2-(4-methoxyphenyl)-4-phenyl-1,3-oxazolid ine-5-carboxylate with dimethyl sulfoxide in the presence of acetic anhydride and acetic acid to obtain 4.alpha.-acetoxy-2.alpha.-benzoyloxy-5.beta.,20-epoxy-1.beta.-hydroxy-7.be ta.,10.beta.-bis(methylthiomethoxy)-9-oxo-11-taxen-13.alpha.-yl (2R,4S,5R)-3-tert-butoxycarbonyl-2-(4-methoxyphenyl)-4-phenyl-1,3-oxazolid ine-5-carboxylate; (b) reacting the product obtained in (a) with activated Raney nickel to obtain 4.alpha.-acetoxy-2.alpha.-benzoyloxy-5.beta.,20-epoxy-1.beta.-hydroxy-7.be ta.,10.beta.-dimethoxy-9-oxo-11-taxen-13.alpha.-yl (2R,4S,5R)-3-tertbutoxy-carbonyl-2-(4-methoxyphenyl)-4-phenyl-1,3-oxazolid ine-5-carboxylate; and (c) reacting the product obtained in (b) with an acid to obtain 4.alpha.-acetoxy-2.alpha.-benzoyloxy-5.beta.,20-epoxy-1.beta.-hydroxy-7.be ta.,10.beta.-dimethoxy-9-oxo-11-taxen-13.alpha.-yl (2R,3S)-3-tert-butoxycarbonylamino-2-hydroxy-3-phenylpropionate. 8. A process for preparing a taxoid of the following formula (l): ##STR29## in which: Z represents a radical of formula (II): ##STR30## in which: R.sub.1 represents a benzoyl radical optionally substituted with one or more identical or different atoms or radicals selected from halogen atoms, alkyl radicals containing 1 to 4 carbon atoms, alkoxy radicals containing 1 to 4 carbon atoms, and trifluoromethyl radicals, a thenoyl radical, a furoyl radical, or a radical R.sub.2 --O--CO-- in which R.sub.2 represents: an alkyl radical containing 1 to 8 carbon atoms, an alkenyl radical containing 2 to 8 carbon atoms, an alkynyl radical containing 3 to 8 carbon atoms, a cycloalkyl radical containing 3 to 6 carbon atoms, a cycloalkenyl radical containing 4 to 6 carbon atoms or a bicycloalkyl radical containing 7 to 10 carbon atoms, these radicals being optionally substituted with one or more substituents selected from halogen atoms; hydroxyl radicals; alkoxy radicals containing 1 to 4 carbon atoms; dialkylamino radicals in which each alkyl portion contains 1 to 4 carbon atoms; piperidino radicals; morpholino radicals; 1-piperazinyl radicals optionally substituted at position 4 with an alkyl radical containing 1 to 4 carbon atoms or with a phenylalkyl radical in which the alkyl portion contains 1 to 4 carbon atoms; cycloalkyl radicals containing 3 to 6 carbon atoms; cycloalkenyl radicals containing 4 to 6 carbon atoms; phenyl radicals optionally substituted with one or more atoms or radicals selected from halogen atoms, alkyl radicals containing 1 to 4 carbon atoms and alkoxy radicals containing 1 to 4 carbon atoms; cyano radicals; carboxyl radicals; and alkoxycarbonyl radicals in which the alkyl portion contains 1 to 4 carbon atoms, a phenyl or .alpha.- or .beta.-naphthyl radical optionally substituted with one or more atoms or radicals selected from halogen atoms; alkyl radicals containing 1 to 4 carbon atoms; and alkoxy radicals containing 1 to 4 carbon atoms, a 5-membered aromatic heterocyclic radical, or a saturated heterocyclic radical containing 4 to 6 carbon atoms, optionally substituted with one or more alkyl radicals containing 1 to 4 carbon atoms, R.sub.3 represents an unbranched or branched alkyl radical containing 1 to 8 carbon atoms, an unbranched or branched alkenyl radical containing 2 to 8 carbon atoms, an unbranched or branched alkynyl radical containing 2 to 8 carbon atoms, a cycloalkyl radical containing 3 to 6 carbon atoms, a phenyl or .alpha.- or .beta.-naphthyl radical optionally substituted with one or more identical or different atoms or radicals selected from halogen atoms, alkyl, alkenyl, alkynyl, aryl, aralkyl, alkoxy, alkylthio, aryloxy, arylthio, hydroxyl, hydroxyalkyl, mercapto, formyl, acyl, acylamino, aroylamino, alkoxycarbonylamino, amino, alkylamino, dialkylamino, carboxyl, alkoxycarbonyl, carbamoyl, alkylcarbamoyl, dialkylcarbamoyl, cyano, nitro and trifluoromethyl radicals, or a 5-membered aromatic heterocycle containing one or more identical or different hetero atoms selected from nitrogen, oxygen and sulphur atoms and optionally substituted with one or more identical or different substituents selected from halogen atoms, alkyl, aryl, amino, alkylamino, dialkylamino, alkoxycarbonylamino, acyl, arylcarbonyl, cyano, carboxyl, carbamoyl, alkylcarbamoyl, dialkylcarbamoyl and alkoxycarbonyl radicals, with the proviso that, in the substituents of the phenyl, .alpha.- or .beta.-naphthyl and aromatic heterocyclic radicals in the definitions of R.sub.2 and R.sub.3, the alkyl radicals and the alkyl portions of the other radicals contain 1 to 4 carbon atoms, and the alkenyl and alkynyl radicals contain 2 to 8 carbon atoms, and the aryl radicals are phenyl or .alpha.- or .beta.-naphthyl radicals, R.sub.4 represents an alkoxy radical containing 1 to 6 carbon atoms in an unbranched or branched chain and R.sub.5 represents an alkoxy radical containing 1 to 6 carbon atoms in an unbranched or branched chain, said process comprising: esterifying a product of formula (III): ##STR31## in which R.sub.4 and R.sub.5 are defined as above with an acid of formula (IV): ##STR32## in which R.sub.1 and R.sub.3 are defined as above, and either R.sub.6 represents a hydrogen atom and R.sub.7 represents a group protecting the hydroxyl function, or R.sub.6 and R.sub.7 together form a saturated 5- or 6-membered heterocycle, or with a derivative of said acid, to obtain an ester of formula (V): ##STR33## in which R.sub.1, R.sub.3, R.sub.4, R.sub.5, R.sub.6 and R.sub.7 are defined as above, and replacing the protective group(s) of said ester of formula (V), represented by R.sub.7 or R.sub.6 and R.sub.7 together, by hydrogen atoms. 9. A process for preparing a new taxoid of the following formula (I): ##STR34## in which: Z represents a hydrogen atom, R.sub.4 represents an alkoxy radical containing 1 to 6 carbon atoms in an unbranched or branched chain and R.sub.5 represents an alkoxy radical containing 1 to 6 carbon atoms in an unbranched or branched chain, said process comprising: treating 10-deacetylbaccatin III of formula (IX): ##STR35## with a silyl halide of formula: in which the symbols R, which may be identical or different, represent an alkyl radical containing 1 to 6 carbon atoms, optionally substituted with a phenyl radical, a cycloalkyl radical containing 3 to 6 carbon atoms or a phenyl radical, to obtain a product of formula (XI): ##STR36## in which R is defined as above, treating said product of formula (XI) with a product of formula: in which R'.sub.4 represents a radical such that R'.sub.4 --O is identical to R.sub.4 defined above and X.sub.1 represents a halogen atom or a reactive ester residue, to obtain a product of formula (XIII): ##STR37## in which R and R.sub.4 are defined as above, replacing the silyl protective groups of said product of formula (XIII) by hydrogen atoms to obtain a product of formula (XIV): ##STR38## in which R.sub.4 is defined as above, and etherifying said compound of formula (XIV) selectively at position 7 with a product of formula (XV): in which R'.sub.5 represents a radical such that R'.sub.5 --O is identical to R.sub.5 defined as above and X.sub.2 represents a reactive ester residue or a halogen atom, to give the product of formula (I) in which Z represents a hydrogen atom. 10. A process for preparing a taxoid of the following formula (I): ##STR39## in which: Z represents a radical of formula (II): ##STR40## in which: R.sub.1 represents a benzoyl radical optionally substituted with one or more identical or different atoms or radicals selected from halogen atoms, alkyl radicals containing 1 to 4 carbon atoms, alkoxy radicals containing 1 to 4 carbon atoms, and trifluoromethyl radicals, a thenoyl radical, a furoyl radical, or a radical R.sub.2 --O--CO-- in which R.sub.2 represents: an alkyl radical containing 1 to 8 carbon atoms, an alkenyl radical containing 2 to 8 carbon atoms, an alkynyl radical containing 3 to 8 carbon atoms, a cycloalkyl radical containing 3 to 6 carbon atoms, a cycloalkenyl radical containing 4 to 6 carbon atoms or a bicycloalkyl radical containing 7 to 10 carbon atoms, these radicals being optionally substituted with one or more substituents selected from halogen atoms; hydroxyl radicals; alkoxy radicals containing 1 to 4 carbon atoms; dialkylamino radicals in which each alkyl portion contains 1 to 4 carbon atoms; piperidino radicals; morpholino radicals; 1-piperazinyl radicals optionally substituted at position 4 with an alkyl radical containing 1 to 4 carbon atoms or with a phenylalkyl radical in which the alkyl portion contains 1 to 4 carbon atoms; cycloalkyl radicals containing 3 to 6 carbon atoms; cycloalkenyl radicals containing 4 to 6 carbon atoms; phenyl radicals optionally substituted with one or more atoms or radicals selected from halogen atoms, alkyl radicals containing 1 to 4 carbon atoms and alkoxy radicals containing 1 to 4 carbon atoms; cyano radicals; carboxyl radicals; and alkoxycarbonyl radicals in which the alkyl portion contains 1 to 4 carbon atoms, a phenyl or .alpha.- or .beta.-naphthyl radical optionally substituted with one or more atoms or radicals selected from halogen atoms; alkyl radicals containing 1 to 4 carbon atoms; and alkoxy radicals containing 1 to 4 carbon atoms, a 5-membered aromatic heterocyclic radical, or a saturated heterocyclic radical containing 4 to 6 carbon atoms, optionally substituted with one or more alkyl radicals containing 1 to 4 carbon atoms, R.sub.3 represents an unbranched or branched alkyl radical containing 1 to 8 carbon atoms, an unbranched or branched alkenyl radical containing 2 to 8 carbon atoms, an unbranched or branched alkynyl radical containing 2 to 8 carbon atoms, a cycloalkyl radical containing 3 to 6 carbon atoms, a phenyl or .alpha.- or .beta.-naphthyl radical optionally substituted with one or more identical or different atoms or radicals selected from halogen atoms, alkyl, alkenyl, alkynyl, aryl, aralkyl, alkoxy, alkylthio, aryloxy, arylthio, hydroxyl, hydroxyalkyl, mercapto, formyl, acyl, acylamino, aroylamino, alkoxycarbonylamino, amino, alkylamino, dialkylamino, carboxyl, alkoxycarbonyl, carbamoyl, alkylcarbamoyl, dialkylcarbamoyl, cyano, nitro and trifluoromethyl radicals, or a 5-membered aromatic heterocycle containing one or more identical or different hetero atoms selected from nitrogen, oxygen and sulphur atoms and optionally substituted with one or more identical or different substituents selected from halogen atoms, alkyl, aryl, amino, alkylamino, dialkylamino, alkoxycarbonylamino, acyl, arylcarbonyl, cyano, carboxyl, carbamoyl, alkylcarbamoyl, dialkylcarbamoyl and alkoxycarbonyl radicals, with the proviso that, in the substituents of the phenyl, .alpha.- or .beta.-naphthyl and aromatic heterocyclic radicals in the definitions of R.sub.2 and R.sub.3, the alkyl radicals and the alkyl portions of the other radicals contain 1 to 4 carbon atoms, and the alkenyl and alkynyl radicals contain 2 to 8 carbon atoms, and the aryl radicals are phenyl or .alpha.- or .beta.-naphthyl radicals, R.sub.4 represents an alkoxy radical containing 1 to 6 carbon atoms in an unbranched or branched chain and R.sub.5 represents an alkoxy radical containing 1 to 6 carbon atoms in an unbranched or branched chain, said process comprising: treating a product of formula (XVI): ##STR41## in which R.sub.1, R.sub.3, R.sub.6 and R.sub.7 are defined as above, with a product of formula (X): in which the symbols R, which may be identical or different, represent an alkyl radical containing 1 to 6 carbon atoms, optionally substituted with a phenyl radical, or a cycloalkyl radical containing 3 to 6 carbon atoms or a phenyl radical, to obtain a product of formula (XVII): ##STR42## in which R, R.sub.1, R.sub.3, R.sub.6 and R.sub.7 are defined as above, functionalizing said compound of formula (XVII) at position 10 with a product of formula: in which R'.sub.4 represents a radical such that R'.sub.4 --O is identical to R.sub.4 defined as above and X.sub.1 represents a halogen atom or a reactive ester residue, to give a product of formula (XVIII): ##STR43## in which R, R.sub.1, R.sub.3, R.sub.4, R.sub.6 and R.sub.7 are defined as above, replacing the silyl protective group of said product of formula (XVIII) by a hydrogen atom to give a product of formula (XIX): ##STR44## in which R.sub.1, R.sub.3, R.sub.4, R.sub.6 and R.sub.7 are defined as above which, when reacted with a product of formula (XV): in which R'.sub.5 represents a radical such that R'.sub.5 O is identical to R.sub.5 defined above and X.sub.2 represents a reactive ester residue or a halogen atom, yields the product of formula (V): ##STR45## in which R.sub.1, R.sub.3, R.sub.4, R.sub.5, R.sub.6 and R.sub.7 are defined as above and replacing the protective group(s) of formula (V) with one or two hydrogen atoms to give a product of formula (I) in which Z represents a radical of formula (II). 11. A process for preparing a taxoid of the following formula (I): ##STR46## in which: Z represents a hydrogen atom or a radical of formula (II): ##STR47## in which: R.sub.1 represents a benzoyl radical optionally substituted with one or more identical or different atoms or radicals selected from halogen atoms, alkyl radicals containing 1 to 4 carbon atoms, alkoxy radicals containing 1 to 4 carbon atoms, and trifluoromethyl radicals, a thenoyl radical, a furoyl radical, or a radical R.sub.2 --O--CO-- in which R.sub.2 represents: an alkyl radical containing 1 to 8 carbon atoms, an alkenyl radical containing 2 to 8 carbon atoms, an alkynyl radical containing 3 to 8 carbon atoms, a cycloalkyl radical containing 3 to 6 carbon atoms, a cycloalkenyl radical containing 4 to 6 carbon atoms or a bicycloalkyl radical containing 7 to 10 carbon atoms, these radicals being optionally substituted with one or more substituents selected from halogen atoms; hydroxyl radicals; alkoxy radicals containing 1 to 4 carbon atoms; dialkylamino radicals in which each alkyl portion contains 1 to 4 carbon atoms; piperidino radicals; morpholino radicals; 1-piperazinyl radicals optionally substituted at position 4 with an alkyl radical containing 1 to 4 carbon atoms or with a phenylalkyl radical in which the alkyl portion contains 1 to 4 carbon atoms; cycloalkyl radicals containing 3 to 6 carbon atoms; cycloalkenyl radicals containing 4 to 6 carbon atoms; phenyl radicals optionally substituted with one or more atoms or radicals selected from halogen atoms, alkyl radicals containing 1 to 4 carbon atoms and alkoxy radicals containing 1 to 4 carbon atoms; cyano radicals; carboxyl radicals; and alkoxycarbonyl radicals in which the alkyl portion contains 1 to 4 carbon atoms, a phenyl or .alpha.- or .beta.-naphthyl radical optionally substituted with one or more atoms or radicals selected from halogen atoms; alkyl radicals containing 1 to 4 carbon atoms; and alkoxy radicals containing 1 to 4 carbon atoms, a 5-membered aromatic heterocyclic radical, or a saturated heterocyclic radical containing 4 to 6 carbon atoms, optionally substituted with one or more alkyl radicals containing 1 to 4 carbon atoms, R.sub.3 represents an unbranched or branched alkyl radical containing 1 to 8 carbon atoms, an unbranched or branched alkenyl radical containing 2 to 8 carbon atoms, an unbranched or branched alkynyl radical containing 2 to 8 carbon atoms, a cycloalkyl radical containing 3 to 6 carbon atoms, a phenyl or .alpha.- or .beta.-naphthyl radical optionally substituted with one or more identical or different atoms or radicals selected from halogen atoms, alkyl, alkenyl, alkynyl, aryl, aralkyl, alkoxy, alkylthio, aryloxy, arylthio, hydroxyl, hydroxyalkyl, mercapto, formyl, acyl, acylamino, aroylamino, alkoxycarbonylamino, amino, alkylamino, dialkylamino, carboxyl, alkoxycarbonyl, carbamoyl, alkylcarbamoyl, dialkylcarbamoyl, cyano, nitro and trifluoromethyl radicals, or a 5-membered aromatic heterocycle containing one or more identical or different hetero atoms selected from nitrogen, oxygen and sulphur atoms and optionally substituted with one or more identical or different substituents selected from halogen atoms, alkyl, aryl, amino, alkylamino, dialkylamino, alkoxycarbonylamino, acyl, arylcarbonyl, cyano, carboxyl, carbamoyl, alkylcarbamoyl, dialkylcarbamoyl and alkoxycarbonyl radicals, with the proviso that, in the substituents of the phenyl, .alpha.- or .beta.-naphthyl and aromatic heterocyclic radicals in the definitions of R.sub.2 and R.sub.3, the alkyl radicals and the alkyl portions of the other radicals contain 1 to 4 carbon atoms, and the alkenyl and alkynyl radicals contain 2 to 8 carbon atoms, and the aryl radicals are phenyl or .alpha.- or .beta.-naphthyl radicals, R.sub.4 represents an alkoxy radical containing 1 to 6 carbon atoms in an unbranched or branched chain and R.sub.5 represents an alkoxy radical containing 1 to 6 carbon atoms in an unbranched or branched chain, said process comprising reacting activated Raney nickel, in the presence of an aliphatic alcohol containing 1 to 3 carbon atoms or an ether, with a product of formula (XXI): ##STR48## in which R.sub.4 is defined as above, and R' and R", which may be identical or different, represent a hydrogen atom or an alkyl radical containing 1 to 6 carbon atoms, an alkenyl radical containing 2 to 6 carbon atoms, an alkynyl radical containing 3 to 6 carbon atoms, a cycloalkyl radical containing 3 to 6 carbon atoms or a cycloalkenyl radical containing 3 to 6 carbon atoms, optionally substituted, or alternatively R' and R", together with the carbon atom to which they are linked, form a cycloalkyl radical containing 3 to 6 carbon atoms or a cycloalkenyl radical containing 4 to 6 carbon atoms, and Z.sub.1 represents a hydrogen atom or a radical of formula (XXII): ##STR49## in which R.sub.1 and R.sub.3 are defined as above and either R.sub.6 represents a hydrogen atom and R.sub.7 represents a group protecting the hydroxyl function, or R.sub.6 and R.sub.7 together form a saturated 5- or 6-membered heterocycle, to obtain a product of formula (XXIII): ##STR50## followed, when Z.sub.1 represents a radical of formula (XXII), by replacing the protective group(s) represented by R.sub.6 or R.sub.6 and R.sub.7 together by hydrogen atoms under the following conditions: 1) when R.sub.6 represents a hydrogen atom and R.sub.7 represents a group protecting the hydroxyl function, said replacing the protective groups by hydrogen atoms is accomplished with at least one inorganic or organic acid in an organic solvent selected from alcohols, ethers, esters, aliphatic hydrocarbons, halogenated aliphatic hydrocarbons, aromatic hydrocarbons and nitrites at a temperature from -10.degree. to 60.degree. C., or with a source of fluoride ions, or with catalytic hydrogenation, or 2) when R.sub.6 and R.sub.7 together form a saturated 5- or 6-membered heterocycle of formula (VI): ##STR51## in which R.sub.1 is defined as above and R.sub.8 and R.sub.9, which may be identical or different, represent a hydrogen atom or an alkyl radical containing 1 to 4 carbon atoms, or an aralkyl radical in which the alkyl portion contains 1 to 4 carbon atoms, or an aryl radical, or alternatively R.sub.8 represents an alkoxy radical containing 1 to 4 carbon atoms or a trihalomethyl radical or a phenyl radical substituted with a trihalomethyl radical and R.sub.9 represents a hydrogen atom, or alternatively R.sub.8 and R.sub.9, together with the carbon atom to which they are linked, form a 4- to 7-membered ring, and further wherein when: a) R.sub.1 represents a tert-butoxycarbonyl radical and R.sub.8 and R.sub.9, which may be identical or different, represent an alkyl radical or an aralkyl or aryl radical, or alternatively R.sub.8 represents a trihalomethyl radical or a phenyl radical substituted with a trihalomethyl radical and R.sub.9 represents a hydrogen atom, or alternatively R.sub.8 and R.sub.9 together form a 4- to 7-membered ring, said replacing the protective groups by hydrogen atoms is accomplished by treating the ester of formula (V) with an inorganic or organic acid, and optionally, with an organic solvent, to obtain the product of formula (VII): ##STR52## in which R.sub.3, R.sub.4 and R.sub.5 are defined as in claim 1, and acylating said product of formula (VII) with benzoyl chloride in which the phenyl ring is optionally substituted; thenoyl chloride; furoyl chloride; or a product of formula (VIII): in which R.sub.2 is defined as above and X represents a halogen atom or a residue --O--R.sub.2 or --O--CO--O--R.sub.2, to obtain a product of formula (I) in which Z represents a radical of formula (II), ##STR53## or b) R.sub.1 represents an optionally substituted benzoyl radical, a thenoyl or furoyl radical or a radical R.sub.2 O--CO-- in which R.sub.2 is defined as above, R.sub.8 represents a hydrogen atom or an alkoxy radical containing 1 to 4 carbon atoms or a phenyl radical substituted with one or more alkoxy radicals containing 1 to 4 carbon atoms and R.sub.9 represents a hydrogen atom, said replacing of the protective group formed by R.sub.6 and R.sub.7 together by two hydrogen atoms is accomplished in the presence of at least one inorganic or organic acid in a stoichiometric or catalytic amount, and in an organic solvent selected from alcohols, ethers, esters, aliphatic hydrocarbons, halogenated aliphatic hydrocarbons and aromatic hydrocarbons at a temperature of from -10.degree. to 60.degree. C. 12. A process according to claim 8, wherein said esterifying step is performed with an acid of formula (IV) in the presence of a condensing agent and an activating agent in an organic solvent at a temperature of from -10.degree. to 90.degree. C. 13. A process according to claim 8, wherein said esterifying step is performed with an acid of formula (IV) in the form of the symmetrical anhydride thereof, in the presence of an activating agent in an organic solvent at a temperature of from 0.degree. to 90.degree. C. 14. A process according to claim 8, wherein said esterifying step is performed with the acid of formula (IV) in halide form or in the form of a mixed anhydride with an aliphatic or aromatic acid, optionally prepared in situ, in the presence of a base, in an organic solvent at a temperature of from 0.degree. to 80.degree. C. 15. A process according to claim 8, further comprising replacing the protective group(s) R.sub.7 or R.sub.6 and R.sub.7 together by hydrogen atoms, wherein: 1) when R.sub.6 represents a hydrogen atom and R.sub.7 represents a group protecting the hydroxyl function, said replacing the protective groups by hydrogen atoms is accomplished with at least one inorganic or organic acid in an organic solvent selected from alcohols, ethers, esters, aliphatic hydrocarbons, halogenated aliphatic hydrocarbons, aromatic hydrocarbons and nitrites at a temperature from -10.degree. to 60.degree. C., or with a source of fluoride ions, or with catalytic hydrogenation, 2) when R.sub.6 and R.sub.7 together form a saturated 5- or 6-membered heterocycle of formula (VI). ##STR54## in which R.sup.1 is defined as in claim 8 and R.sub.8 and R.sub.9, which may be identical or different, represent a hydrogen atom or an alkyl radical containing 1 to 4 carbon atoms, or an aralkyl radical in which the alkyl portion contains 1 to 4 carbon atoms, or an aryl radical, or alternatively R.sub.8 represents an alkoxy radical containing 1 to 4 carbon atoms or a trihalomethyl radical or a phenyl radical substituted with a trihalomethyl radical and R.sub.9 represents a hydrogen atom, or alternatively R.sub.8 and R.sub.9 together with the carbon atom to which they are linked, form a 4- to 7-membered ring, and further wherein when: a) R.sub.1 represents a tert-butoxycarbonyl radical and R.sub.8 and R.sub.9 which may be identical or different, represent an alkyl radical or an aralkyl or aryl radical, or alternatively R.sub.6 represents a trihalomethyl radical or a phenyl radical substituted with a trihalomethyl radical and R.sub.9 represents a hydrogen atom, or alternatively R.sub.8 and R.sub.9 together form a 4- to 7-membered ring, the ester of formula (V) is treated with an inorganic or organic acid, and optionally, in an organic solvent, to obtain the product of formula (VII): ##STR55## in which R.sub.3, R.sub.4 and R.sub.5 are defined in claim 8, and said product of formula (VII) is acylated with benzoyl chloride in which the phenyl ring is optionally substituted or thenoyl chloride, or furoyl chloride or a product of formula (VIII): in which R.sub.2 is defined in claim 8 and X represents a halogen atom or a residue --O--R.sub.2 or --O--CO--O--R.sub.2, to obtain a product of formula (I) in which Z represents a radical of formula (II), b) when R.sub.1 represents an optionally substituted benzoyl radical, a thenoyl or furoyl radical or a radical R.sub.2 O--CO-- in which R.sub.2 is defined as above, R.sub.6 represents a hydrogen atom or an alkoxy radical containing 1 to 4 carbon atoms or a phenyl radical substituted with one or more alkoxy radicals containing 1 to 4 carbon atoms and R.sub.9 represents a hydrogen atom, the protective group formed by R.sub.6 and R.sub.7 is replaced by hydrogen atoms in the presence of at least one inorganic or organic acid in a stoichiometric or catalytic amount, and in an organic solvent selected from alcohols, ethers, esters, aliphatic hydrocarbons, halogenated aliphatic hydrocarbons and aromatic hydrocarbons at a temperature of from -10.degree. to 60.degree. C. 16. A process according to claim 15, wherein when R.sub.6 and R.sub.7 together form a saturated 5- or 6-membered heterocycle of formula (VI), and R.sub.8 and R.sub.9 which may be identical or different, represent an aralkyl radical in which the alkyl portion contains 1 to 4 carbon atoms, the aryl portion of said aralkyl radical represents a phenyl radical optionally substituted with one or more alkoxy radicals containing 1 to 4 carbon atoms. 17. A process according to claim 15, wherein when R.sub.6 and R.sub.7 together form a saturated 5- or 6-membered heterocycle of formula (VI), and R.sub.8 and R.sub.9, which may be identical or different, represent an aryl radical, said aryl radical is a phenyl radical optionally substituted with one or more alkoxy radicals containing 1 to 4 carbon atoms. 18. A process according to claim 15, wherein said temperature ranges from 15.degree. to 30.degree. C. 19. A process according to claim 15, wherein said source of fluoride ions is a hydrofluoric acid/triethylamine complex. 20. A process according to claim 15, wherein said trihalomethyl radical is trichloromethyl. 21. A process according to claim 15, wherein when said ester of formula (V) is treated in an organic solvent, said organic solvent is an alcohol. 22. A process according to claim 7, wherein said activated Raney nickel is present in step (b) in an ethanolic suspension and further wherein said acid in step (c) is an ethanolic solution of hydrochloric acid.