Optical resolution and absolute configuration of N-benzyloxycarbonyl-alpha-alkoxyglycines

Optical resolution of racemic N-benzyloxycarbonyl-protected alpha-alkoxy-gl ycines, (+/-)-Cbz-Gly(OR)-OH (R = Et and Pr-2), was achieved by means of fr actional crystallization of diastereomeric salts with (+)-(1S,2S)-2-amino-1 -phenyl-1,3-propanediol or diastereomeric esters of (+)- or (-)-menthol. Th e D- and L-configurations were assigned to the (+)- and (-)-Cbz-Gly(OR)-OH, respectively, based on L-enantioselective enzymatic hydrolysis of (+/-)-Cb z-Gly(OR)-OR' (R = Me, Et, and Pr-i; R' = CH2CF3 and Me) using porcine panc reatic lipase and papain. Chiroptical properties and HPLC retention times o f D- and L-Gly(OR)-residue (R = Me and Pr-i)-containing peptides were compa red in relation to their configurational assignments. (C) 1999 Wiley-Liss, Inc.