ASYMMETRIC-SYNTHESIS OF ALPHA-HYDROXY ACIDS VIA BETA-LACTAMS

A diastereoselective synthesis of beta-lactams 5a-e and 6a-e has been achieved, via a Staudinger reaction using imines derived from (1S)-(+) -camphor-10-sulfonamide, in good yields. The major diastereomers 6a-e were isolated in pure form by crystallization. The absolute configurat ion of the beta-lactam 6b was established as 3R and 4S by X-ray analys is. The major diastereomers 6b and 6c were converted into enantiomeric ally pure alpha-hydroxy ester derivatives 7-9. Copyright (C) 1996 Else vier Science Ltd