Use of enantio-, chemo- and regioselectivity of acylase I. Resolution of polycarboxylic acid esters

Acylase I was used to catalyze the enantioselective butanolysis of trimethy l 2-[(carboxymethyl)oxy]succinate (E=30) and N-carboxymethylaspartate (E=9) exclusively at the most sterically hindered of tile three ester group's (t he position a to tile asymmetric centre). Gram-scale resolution allowed the preparation of the less reactive trimethyl (S)-2-[(carboxymethyl)oxy]succi nate (96% e.e.), that of the (R)-butyldimethyl regioisomer (78% e.e.) at 55 % conversion and finally the preparation of the corresponding trisodium car boxylate by saponification. Acylase I was shown to transform (+/-)-methyl N -acetylmethionine and (+/-)-valine to the corresponding (S)-amino acids thr ough ester hydrolysis-N-acetyl transfer sequence with absolute chemo- and e nantioselectivity. Butanolysis of methyl N-acetylmethionine stopped in the formation of the butyl ester (E=12), the valine derivative being totally un reactive. (C) 2001 Elsevier Science Ltd. All rights reserved.