Enantioselective acylation of (±)- cis-flavan-4-ols catalyzed by lipase from Candida cylindracea ( CCL) and the synthesis of enantiopure flavan-4-ones

Abstract

Lipase Candida cylindracea ( CCL) catalyzed acylation of (±)- cis-flavan-4-ols using vinyl acetate as the acyldonor in DME–toluene (1:2) gave (−)-(2 R,4 R)-4-acetoxyflavans 9a– m and (+)-(2 S,4 S)-flavan-4-ols 10a– m in high enantiomeric excess. (+)-(2 S,4 S)-Flavan-4-ols 10a– m were converted to (−)-(2 S)-flavan-4-ones 12a– m.