Improvement of lipase-catalyzed kinetic resolution by tandem transesterification

Abstract

Glycidyl acetate may be prepared enantioselectively from glycidyl butyrate by sequential enzymatic resolution. First, porcine pancreas lipase selectively forms ( R)-glycidol by transesterification in dehydrated butanone. Then the lipase transesterifies ( R)-glycidol selectively to glycidyl acetate. A model incorporating ping-pong bi-bi kinetics for this tandem reaction was worked out. For both reaction steps the enantiomeric ratios were 7. Other model parameters were also determined. The experimental results were adequately described by the model. The maximum enantiomeric excess of glycidyl acetate was raised from 65 to 89% by carrying out a tandem reaction instead of a single-resolution reaction. However, the model predicts that the amount of enantiopure product that may be obtained in a tandem reaction is limited as a result of equilibrium restrictions.