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 α′-acetoxy and α′-hydroxy-α-methoxy cyclic enones starting from α-hydroxy cyclic enones is described. Protection of 1,2-diketones, manganese(III) acetate-mediated acetoxylation followed by enzyme-mediated hydrolysis of α′-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.