SYNTHESES OF HIGHLY CONSTRAINED BETA-ARYL ISOHEXANOIC ACID-DERIVATIVES VIA ASYMMETRIC MICHAEL ADDITION

A series of enantiomerically pure highly sterically hindered beta-bran ched isohexanoic acid derivatives have been synthesized with high dias tereoselectivity via asymmetric Michael addition. The X-ray crystal st ructure of imethylphenyl)isohexanyl]-4-phenyl-2-oxazolidonone demonstr ated that the beta-configuration was induced from the Si-face, and tha t the torsional angle chi(2) was restricted by the bulky beta-isopropy l group to the range expected from molecular modeling. Copyright (C) 1 996 Elsevier Science Ltd