Gelozymes in organic synthesis. Part IV: Resolution of glycidate esters with crude Mung bean ( Phaseolus radiatus) epoxide hydrolase immobilized in gelatin matrix

Abstract

A crude extract of Mung bean meal ( Phaseolus radiatus) possessing epoxide hydrolase activity immobilized in gelatin gel (gelozyme) is employed in the stereoselective epoxide ring opening of glycidate esters. Thus, ethyl trans-(±)-3-phenyl glycidate 1a and methyl trans-(±)-3-(4-methoxyphenyl) glycidate 1b gave (2 S,3 R)-glycidate esters (ee >99% and 45% yield) with gelatin immobilized enzyme in diisopropyl ether. The corresponding (2 R,3 S)-enantiomer of 1a was hydrolyzed by an epoxide hydrolase to predominantly give the anti-product, ethyl (2 R,3 R)-2,3-dihydroxy-3-phenylpropanoate, with a diastereomeric excess of 78% and ee 94% (40%). A small amount (5%) of racemic syn-product was also obtained as a result of the spontaneous hydrolysis. In the case of 1b, the hydrolysis product was racemic due to high reactivity of the glycidate toward water.