Yee-Shing Wong

Novel, stereoselective syntheses of penem antibiotics: efficient, formal syntheses of SCH 34343

Abstract Novel, stereoselective syntheses of (3S, 4R, 5R)-1-(allyloxycarbonyl)methyl-3-[1-hydroxyethyl]-4-β-naphthoxy(thiocarbonyl)thio-2-azetidinone (13) and (3S, 4R, 5R, 3′S, 4′R, 5′R)-4,4′-dithio-bis-1-(allyloxy-carbonyl)methyl-3-[-1-hydroxyethyl]-2-azetidinone (22), key intermediates in the synthesis of the penem antibiotic Sch 34343, were developed starting from readily available 6-aminopenicillanic acid. Advantages of these routes include 1) the highly stereospecific introduction of the hydroxyethyl sidechain with the desired (R)-configuration and 2) the retention of the sulfur of the starting material.