Maceration of Plant Tissues by Pectin trans-Eliminase

Methyl (±)-11-(2-hydroxyethyl)thio-6,11-dihydrodibenzb,e]oxepin-2-carboxylate (5) was enantioselectively acylated with acetic anhydride in an organic medium by Lipase Amano P to give methyl (–)-11-(2-acetoxyethyl)thio-6,11-dihydrodibenzb,e]oxepin-2-carboxylate (8), and the (+)-enantiomer by Lipase Sigma Type VII. Using Lipase Amano P, (+)- and (–)-(5) could be prepared with high optical purity (84–94% e.e.). These products were respectively converted to (+)- and (–)-KW-4099, which had antiallergic activity with complete retention of the optical purity.