ENZYMATIC PREPARATION OF OPTICALLY-ACTIVE SILYLMETHANOL DERIVATIVES HAVING A STEREOGENIC SILICON ATOM BY HYDROLASE-CATALYZED ENANTIOSELECTIVE ESTERIFICATION

Kinetic resolution of ethylmethylphenylsilylmethanol, a primary alcohol having a stereogenic silicon atom, was tried by hydrolase-catalyzed enantioselective reactions. Among twenty kinds of hydrolases examined, a commercial crude papain preparation was found to exhibit the highest enantioselectivity with moderate activity toward the silicon-containing alcohol on esterification with 5-phenylpentanoic acid in an organic solvent system, and the (+)-enantiomer of 92%ee was obtained as the remaining substrate. Several silylmethanol derivatives could be also resolved by this enantioselective esterification, even though it was difficult to synthesize such chiral quaternary silanes with high optical purity by chemical methods due to the absence of leaving groups on the silicon atom. These results demonstrate that enzymes can recognize the configuration not only of carbon atoms but also of silicon atoms, and indicate the usefulness of biocatalysts for preparing optically active silanes.