Process for the preparation of an optically active ester

摘要

The invention relates to a process for the preparation of an optically active compound from raw materials comprising a di-ester and a chiral hydroxy-compound according to formula (I):
wherein:
- R 1 , R 2 , R 4 and R 5 each independently represent hydrogen or an alkyl group with 1-20 C-atoms, an alkenyl group with 2-20 C-atoms, an alkynyl group with 2-20 C-atoms,or an (hetero)aryl group with 4-20 C-atoms optionally containing one or more O, S or N atoms,
- R 3 represents an alkyl group with 1-20 C-atoms, an alkenyl group with 2-20 C-atoms, an alkynyl group with 2-20 C-atoms, or an (hetero)aryl group with 4-20 C-atoms optionally containing one or more O, S or N atoms,
- the compound according to formula (I) comprises at least one chiral centre that has an ±-carbon relative to a secondary hydroxy group,
comprising the steps of
a) bringing the di-ester, optionally a solvent, and the chiral hydroxy-compound according to formula (I) together to form a reaction system;
b) adding an asymmetric transesterification catalyst, a racemisation catalyst and optionally a racemisation catalyst re-activating compound to the reaction system;
c) bringing the reaction system to conditions where racemisation and enantioselective transesterefication take place, whereby the optically active compound is formed,
whereby steps a), b) and c) may be executed sequentially or simultaneously, and whereby the chiral hydroxy-compound according to formula (I) may in step a) be partially or wholly replaced by the combination of the corresponding ketone and a reducing agent.