Synthesis of optically active α-methylene γ-lactones through lipase-catalyzed kinetic resolution

Abstract

The lipase-catalyzed kinetic resolution of the γ-hydroxy esters 1a,b and their subsequent acid-mediated cyclization afford the optically active α-methylene γ-lactones 2a,b in high yields (71–89%) and in up to 95% enantiomeric excess. The direct enzymatic lactonization of the racemic γ-hydroxy esters 1a,b to the lactones 2a,b represents a less satisfactory alternative, since poor enantioselectivies have been obtained.