RESOLUTION OF HOMOALLYLIC ALCOHOLS CONTAINING DITHIOKETENE ACETAL FUNCTIONALITIES - SYNTHESIS OF OPTICALLY-ACTIVE GAMMA-LACTONES BY A COMBINATION OF CHEMICAL AND ENZYMATIC METHODS

Racemic homoallylic alcohols 1-3 containing dithioketeneacetal functionalities were prepared by addition of aldehydes to the allylic anions of ketene dithioacetals or 2-alkenyl-1,3-dithiane in a regio- and stereoselective manner. Lipase-catalyzed hydrolyses of the corresponding acetates 7-9 afforded optically active alcohols 1-3, which were treated with mercuric chloride to give gamma-lactones such as natural hop lactone, whiskey lactone, and cognac lactone.