Synthesis of a Chiral α-(Aminooxy)arylacetic Ester. I. A Route through Optical Resolution of a Racemic α-(Phthalimidooxy)arylacetic Acid

A synthetic route has been developed to the synthesis of a chiral O-alkyloxime (S)-16, which can be a synthetic intermediate for a potent antipsedomonal cephalosporin antibiotic M-14659 (1). The oxime moiety in (S)-16 has a chiral center at the carbon atom adjacent to the oxygen atom. We have achieved that (S)-16 can be prepared via t-butyl 2-aminooxy-2-[3,4-(isopropylidenedioxy)phenyl]acetate [(S)-15] from an optically active α-(phthalimidooxy) acid (S)-12a which is obtained by resolution using quinine. It has been demostrated that M-14659 prepared from (S)-16 is completely free from its (R)-diastereomer.