Comparison of the chiral recognition of prochiral substrates in the acetylation reaction by a novel lipase (CSL) from the yeast, Cryptococcus spp. S-2 with immobilized PPL : Enzyme-catalyzed desymmetrization and asymmetrization of prochiral 2-substituted 1,3-propanediols by CSL and immobilized PPL

Abstract

In order to elucidate the nature of a novel lipase (CSL), isolated from the yeast Cryptococcus spp. S-2, in chiral recognition by comparison with that of immobilized PPL, the desymmetrization and asymmetrization of prochiral 2-phenyl-1,3-propanediol ( 1a), 2-benzyl-1,3-propanediol ( 1b), 2-methyl-2-phenyl-1,3-propanediol ( 1c), 2-benzyl-2-methyl-1,3-propanediol ( 1d), 2-ethyl-2-phenyl-1,3-propanediol ( 1e), and 2-benzyl-2-ethyl-1,3-propanediol ( 1f) by acetylation was investigated. Acetylation of 1a with excess vinyl acetate by the CSL-enzyme catalyst gave the corresponding monoacetate 2a with high enantioselectivity (80% ee) in 46% yield. Very high levels of desymmetrization were observed in the tertiary systems of 1c– f, giving the corresponding monoacetates 2c– f, respectively, in >97%. In the desymmetrization of diols 1a, 1c, 1d, and 1f, the sense of chiral differentiation of CSL was opposite to that of immobilized porcine pancreatic lipase (PPL).