PRACTICAL RESOLUTION OF AN ATROPOISOMERIC ALPHA,ALPHA-DISUBSTITUTED GLYCINE WITH L-PHENYLALANINE CYCLOHEXYLAMIDE AS CHIRAL AUXILIARY

L-Phenylalanine cyclohexylamide has been used as a chiral auxiliary fo r the medium-scale resolution of 2',1':1,2;1 '',2 '':3,4-dinaphthcycio hepta- 1,3-diene-6-amino-6-carboxylic acid (Bin), an alpha,alpha-disub stituted glycine with only axial dissymmetry. Coupling of X-Bin-OH (X= Ac; Bz) with H-(L)-Phe-NH-C6H11 by the EDC/HOBt method gave the dipept ide diastereoisomers X-(R)-Bin-(L)-Phe-NH-C6H11 and X-(S)-Bin-(L)-Phe- NH-C6H11, which were separated by crystallization (X=Bz) and/or chroma tography. Extensive acidic hydrolysis, followed by esterification of t he resulting free amino acid enantiomers, led to enantiomerically pure (-)-(R)-H-Bin-OMe and (+)-(S)-H-Bin-OMe with high yields. (C) 1998 El sevier Science Ltd. All rights reserved.