Chemoenzymatic synthesis of enantiomerically enriched 2-oxobicyclo[ m.1.0]alkan-3-yl acetate derivatives

Abstract

Racemic α′-acetoxy α,β-unsaturated cyclopentanone and cyclohexanone have been resolved into the corresponding enantiomerically enriched α′-hydroxylated and acetoxylated compounds with 96–97% ee via PLE hydrolysis. Stereoselectivity in the palladium(II)-catalyzed reaction between the enantiomerically enriched α′-acetoxylated compounds and diazomethane has been investigated. In the α′-acetoxylated cyclopentenone, preferential cyclopropanation occurs in the anti-form, whereas α′-acetoxylated cyclohexenone affords both syn- and anti-products ( syn: anti, 61:36%). The relative configuration of the products was determined by NOE experiments.