Kinetic resolution of esters of amino acids in t‐butanol containing 5% water catalyzed by a stable industrial alkaline protease

Abstract

AbstractWe developed a procedure for the resolution of esters of amino acids in 95% t‐butanol, followed by saponification of the unreacted esters to afford both enantiomers with high yield and optical purity. The hydrolysis, catalyzed by alkaline protease, was conducted in a mixture of t‐butanol (95%) and water (5%) at 25°C, with a pH controlled at pH 8.5 by the addition of NaOH (2 M). The hydrolyzed L‐amino acid, which was insoluble under these conditions, precipitated during the course of hydrolysis. After separation of the precipitate, the pH of the filtrate was adjusted to 11.5 to saponify the unreacted ester. The D‐antipode precipitated at pH 6.2–6.5. Both optically pure antipodes were obtained with high enantiomeric excesses and yields by simple filtration. © 1994 Wiley‐Liss, Inc.