PROCESS FOR PREPARING CEPHALOTAXINE ESTERS

摘要

A process for preparing cephalotaxine esters corresponding to the following general formula I which comprises the cephalotaxine backbone: C(R1) (R2) (XH)COO[CTX] wherein CTX represents the cephalotaxine backbone, being optionally substituted and/or dehydrogenated, in which formula I, X is a heteroatom, preferably an oxygen, a sulfur or a nitrogen, R1 and R2, taken separately, may be alkyl, cycloalkyl, heteroalkyl, aryl, heteroaryl, heterocycloalkyl or aralkyl groups, said groups being optionally interrupted by ester functions, or groups that can form one or more rings or a heterocycle together, consisting in bringing the corresponding cephalotaxine compound, or salts, isomers or tautomeric forms thereof, which is free or which is in the form of a metal alkoxide corresponding to the following general formula CTXOM, wherein CTX represents the cephalotaxine backbone, being optionally substituted and/or dehydrogenated, in which M is a hydrogen atom or a metal atom, into contact with a heterocyclic side chain precursor having both a bifunctional protected (bidentate) and activated (acylating) form of an acid bearing a hydrogenated heteroatom, in the alpha (a) position with respect to the carboxyl group, and corresponding to the following general formula: in which case W is a carbon, sulfur, silicon or bore atom, X, R1 and R2 have respectively the same meaning as above, it being possible for R1 and R2 to form a ring or a heterocycle together, and Y and Z are alkyl or heteroalkyl radicals, or monovalent heteroatoms, which may be identical or different, in an independent manner, or may fuse so as to give a divalent heteroatom, it being possible for the X-W bond to be covalent or ionic.