Preparation of optically active diol derivatives by the enzymatic hydrolysis of cyclic carbonates

A simple enzymatic method for the preparation of optically active 1,2- and 1,3-diol derivatives is disclosed. In the screening of enzymes, racemic 4-[(2-benzyloxy)ethyl]-1,3-dioxolan-2-one (1a) was enantioselectively hydrolyzed by porcine pancreas lipase (PPL) to give optically active (R)-1a and (S)-4-(benzyloxy)butane-1,2-diol (2a). The addition of 10% i-Pr2O to the reaction system dramatically improved the reactivity to afford optically pure (R)-1a in 31% yield. PPL also catalyzed the hydrolysis of several five-membered cyclic carbonates with high enatioselectivity. It is noteworthy that the increment of the carbon number of the substituents reflects the drastic increase in enantioselectivity. On the other hand, the hydrolyses of six- and seven-membered cyclic carbonates were also catalyzed by PPL. In particular, the reaction of a six-membered substrate enantioselectively proceeded. This reaction afforded optically active 1,3-diol derivatives which could not be directly prepared by hitherto known methods using hydrolytic enzymes.