Process for the preparation of taxane derivatives

Process for the preparation of a compound of the formula (VIII) ##STR15## in which:

• Ar represents a phenyl or .alpha.- or .beta.-naphthyl radical unsubstituted or substituted by at least one substituent selected from the group consisting of a halogen atom and an alkyl, alkenyl, alkynyl, aryl, arylalkyl, alkoxy, alkylthio, aryloxy, arylthio, hydroxyl, hydroxyalkyl, mercapto, formyl, acyl, acylamino, aroylamino, alkoxycarbonylamino, amino, alkylamino, dialkylamino, carboxyl, alkoxycarbonyl, carbamoyl, dialkylcarbamoyl, cyano, and a trifluoromethyl radical, wherein the alkyl radical and alkyl portions of the other radicals comprise 1 to 4 carbon atoms, the alkenyl and alkynyl radicals comprise 3 to 8 carbon atoms, and the aryl radicals are phenyl or .alpha.- or .beta.-naphthyl radicals;
• R.sub.3 represents a trihalomethyl radical or a phenyl radical substituted by a trihalomethyl radical;
• and
• R.sub.4 represents a hydrogen atom, a benzoyl radical, or a a radical R.sub.2 --O--CO-- in which R.sub.2 represents:
• a straight or branched alkyl radical comprising 1 to 8 carbon atoms, an alkenyl radical comprising 2 to 8 carbon atoms, an alkynyl radical comprising 3 to 8 carbon atoms, a cycloalkyl radical comprising 3 to 6 carbon atoms, a cycloalkenyl radical comprising 4 to 6 carbon atoms, or a bicycloalkyl radical comprising 7 to 10 carbon atoms, these radicals being unsubstituted or substituted with at least one substituent selected from the group consisting of a halogen atom, a hydroxyl radical, an alkoxy radical comprising 1 to 4 carbon atoms, a dialkylamino radical in which each alkyl portion comprises 1 to 4 carbon atoms, a piperidino radical, a morpholino radical, a 1-piperazinyl radical (unsubstituted or substituted at position 4 by an alkyl radical comprising 1 to 4 carbon atoms or by a phenylalkyl radical in which the alkyl portion comprises 1 to 4 carbon atoms), a cycloalkyl radical comprising 3 to 6 carbon atoms, a cycloalkenyl radical comprising 4 to 6 carbon atoms, a phenyl radical, a cyano radical, a carboxyl radical, or an alkoxycarbonyl radical in which the alkyl portion comprises 1 to 4 carbon atoms, wherein the cycloalkyl, cycloalkenyl, or bicycloalkyl radicals may be substituted by at least one alkyl radical comprising 1 to 4 carbon atoms;
• a phenyl radical unsubstituted or substituted by at least one substituent selected from the group consisting of an alkyl radical comprising 1 to 4 carbon atoms and an alkyloxy radical comprising 1 to 4 carbon atoms;
• or
• a saturated or unsaturated nitrogen-containing heterocyclic radical comprising 5 or 6 members, unsubstituted or substituted by at least one alkyl radical comprising 1 to 4 carbon atoms;
• and
• G.sub.1 and optionally G.sub.2 represent a protecting group of the hydroxyl functional group;
• wherein said process comprises esterifying a compound of the formula (III) ##STR16## in which G.sub.1 and G.sub.2 are described above, by means of an acid of the formula (VII) ##STR17## in which Ar, R.sub.3, and R.sub.4 are described above.