Synthesis of a chiral α-(aminooxy)arylacetic ester. II.1) a route through a chiral 2-hydroxy-2-phenylacetic acid derivative

Abstract

A simple and practical synthetic route has been developed for the synthesis of a chiral α-(aminooxy) ester (S)-16, which is a synthetic intermediate for a potent antipseudomonal cephalosporin antibiotic M-14659. In this synthetic route, the key intermediate is α-hydroxy acid (R)-7 (100%ee), which is prepared by an asymmetric reduction of α-keto ester with NaBH4-(R,R)-tartaric acid followed by a hydrolysis and an optical resolution using L-Leu-NHNH2. (S)-16 is obtained stereoselectively through 3 steps from (R)-7. HPLC analyses and NMR studies have proved that the (S)-16 thus prepared is completely optically pure.