A new and efficient chemoenzymatic route to both enantiomers of α′-acetoxy and α′-hydroxy-α-methoxy cyclic enones

Abstract

A chemoenzymatic synthesis of both enantiomers of the pharmacologically interesting alpha'-acetoxy and alpha'-hydroxy-alpha-methoxy cyclic enones starting from alpha-hydroxy cyclic enones is described. Protection of 1,2-diketones, manganese(III) acetate-mediated acetoxylation followed by enzyme-mediated hydrolysis of alpha'-acetoxy enones gives acetoxy enones 3a-d and hydroxy enones 4a-d with high enantiomeric excesses (up to 99%) and good yields. The transesterification of rac-4b in the presence of DMAP afforded (+)-4b and (-)-3b in high enantiomeric excesses (91-94%) and good chemical yields. (c) 2006 Elsevier Ltd All rights reserved.