Abstract: S-(+)-2,2-dimethylcyclopropanecarboxylic acid (S-(+)-DMCPA) was synthesized by asymmetric hydrolysis of racemic ethyl-2,2- dimethylcyclopropane carboxylate (DMCPE) over different lipases. Among the five enzymes investigated, Novozyme 435 showed higher enantioselectivity and activity. The influence of reaction parameters, such as ionic strength, the ratio of lipase/DMCPE, buffer pH, reaction temperature, and reaction time, on the biosynthesis of S-(+)-DMCPA was investigated. The optimum DMCPE concentration, enzyme dosage, buffer pH, reaction temperature, and reaction time were 65 mmol/L, 16 g/L, 7.2, 30 oC, and 64 h, respectively. Under the optimal conditions, the higher yield of 45.6% and enantiomeric excess of 99.2% for S-(+)-DMCPA were obtained. The biocatalytic activity of Novozyme 435 was relatively stable, retaining 70.3% of the initial activity after reuse three times. The results demonstrated that lipase Novozyme 435 is a suitable biocatalyst for the synthesis of S-(+)-DMCPA and has great potential for industrial applications.

Key words: lipase, ethyl-2, 2-dimethylcyclopropanecarboxylate, asymmetric hydrolysis, S-(+)-2, 2-dimethylcyclopropanecarboxylic acid, chiral intermediate