Microbially-aided preparation of (S)-2-methoxycyclohexanone key intermediate in the synthesis of sanfetrinem

(S) 2-Methoxycyclohexanone 1, useful intermediate in the synthesis of Sanfetrinem 2, is obtained from (S) alpha-benzylidene cyclohexanol 4, derived from the ketone 3 through a short sequence involving as key step yeast reduction of the carbonyl group. The (R) enantiomer of 1 is similarly accessible from the (R) enantiomer of 4 obtained either upon Candida lipolytica-mediated reduction of 3 or from (R,S)-4 by porcine pancreatic lipase catalyzed acetylation with vinyl acetate. Also the saturated carbinols 7 and 8, which accompany 4 in the microbial reduction of 3, are converted into 1 through unexceptional steps. Nocardia opaca, Pichia etchelsii and Mucor subtilissimus provide from 3 upon reduction (S)-configurated 4, 7 and 8 possessing moderate-high ee values. (C) 1997, Elsevier Science Ltd.