Biohydrogenation of unsaturated compounds by Saccharomyces cerevisiae. Part 2: (S)-(–)-Ethyl 4-hydroxy-3-methylbutanoate as a chiral synthon for the preparation of (25S)-26-hydroxycholesterol

Abstract
(25S)-26-Hydroxycholesterol (1b) has been synthesized from stigmasterol (4a) and (S)-(–)-ethyl 4-hydroxy-3-methylbutanoate (2a), the latter having the necessary chirality for the synthesis of the steroidal side-chain.