Free and Immobilized Lecitase™ Ultra as the Biocatalyst in the Kinetic Resolution of ()-4-Arylbut-3-en-2-yl Esters.

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 ()-alcohols and unreacted ()-esters with good to excellent enantiomeric excesses (ee 90-99%). These conditions and enzyme were also suitable for the kinetic separation of racemic ()-4-phenylbut-3-en-2-yl butyrate analogs containing methyl substituents on the benzene ring (,), but they did not show any enantioselectivity toward ()-4-(4'-methoxyphenyl)but-3-en-2-yl butyrate ().