Use of lipase-catalyzed kinetic resolution for the enantioselective approach toward sesquiterpenes containing quaternary centers: the cuparane family

The enzymatic kinetic resolution of a suitable hydroxylated precursor of the deoxygenated molecule 3, a key intermediate in a synthesis of the cuparane skeleton, was investigated by screening a range of lipases for enantioselective transesterification with vinyl acetate. CAL-B proved to be the best lipase, affording both enantiomers in high enantiomeric excess (>98% ee). Single-crystal X-ray diffraction analysis enabled assignment of the absolute configuration and the enantiospecificity of the tested lipases. (C) 2003 Elsevier Ltd. All rights reserved.