Simple Approach to Optically Active Drimane Sesquiterpenes Based on Enzymatic Resolution

Abstract

When the β-acyloxy esters (±)-10 and (±)-11 were exposed to the lipase OF-360 from Candida rugosa or immobilized lipase OF-360 in a water-saturated organic solvent, the hydrolyzed product (8aS)- was obtained in high chemical (40%) and optical (>99%ee) yields. The absolute structure of (8aS)-6 was confirmed by the fact that (8aS)-6 was converted into an authentic sample γ-keto nitrile (8aS)-17. Treatment of the diol (±)-12 with isopropenyl acetate in the presence of the lipase Godo E-4 from Pseudomonas sp. provided the unchanged (8aR)-12 (89%ee) in 42% yield.