Kinetic resolution of 2-chloro-3,3,3-trifluoropropanoic acid esters catalyzed by lipase from Candida rugosa

Abstract

By screening around 30 commercially available lipases and esterases, two enzymes, C. rugosa lipase and P. fluorescens esterase, were found to posess catalytic activity and enantioselectivity (E˜10) for the hydrolysis of 2-chloro-3,3,3-trifluoropropanoic acid (CTFPA) methyl and ethyl ester. Both enzymes were tentatively assigned to be (S)-selective based on the assumption that they have the same stereopreference as in the hydrolysis of methyl 2-chloropropanoate, which is a non-fluorinated analogue of CTFPA. The enzymes were applied in the kinetic resolution of CTFPA ethyl ester and 95% ee of the remaining ester could be achieved at 60% conversion. The crosslinked enzyme aggregate (CLEA) of C. rugosa lipase was found to catalyze enantioselective transesterification (E˜40) of CTFPA methyl ester with ethanol. By conducting the transesterification in a 10-mL packed-bed reactor containing CLEA, it was possible to convert racemic CTFPA methyl ester into the mixture of (S)-methyl and (R)-ethyl esters with 82% and 90% ee, respectively, at 4.0 g/L-1/h-1 space-time yield, which decreased to 1.0 g/L-1/h-1 after four repetitive batches.