Free and immobilized lecitase™ ultra as the biocatalyst in the kinetic resolution of (E)‐4‐arylbut‐3‐en‐2‐yl esters

Abstract

The influence of buffer type, co‐solvent type, and acyl chain length was investigated for the enantioselective hydrolysis of racemic 4‐arylbut‐3‐en‐2‐yl esters using Lecitase™ Ultra (LU). Immobilized preparations of the Lecitase™ Ultra enzyme had significantly higher activity and enantioselectivity than the free enzyme, particularly for 4‐phenylbut‐3‐en‐2‐yl butyrate as the substrate. Moreover, the kinetic resolution with the immobilized enzyme was achieved in a much shorter time (24–48 h). Lecitase™ Ultra, immobilized on cyanogen bromide‐activated agarose, was particularly effective, producing, after 24 h of reaction time in phosphate buffer (pH 7.2) with acetone as co‐solvent, both (R)‐alcohols and unreacted (S)‐esters with good to excellent enantiomeric excesses (ee 90–99%). These conditions and enzyme were also suitable for the kinetic separation of racemic (E)‐4‐phenylbut‐3‐en‐2‐yl butyrate analogs containing methyl substituents on the benzene ring (4b,4c), but they did not show any enantioselectivity toward (E)‐4‐(4’‐methoxyphenyl)but‐3‐en‐2‐yl butyrate (4d).