A novel approach to a precursor of the carbapenem antibiotic PS-5 via aziridine stereospecific carbonylation

Cobalt cartonyl-catalyzed carbonylative ring expansion of optically pure ci s-1-benzyl-3-ethyl-2-hydroxymethylaziridine (5) to trans-beta -lactam (8) a fforded a key precursor of the carbapenem antibiotic (+)-PS-5. Aziridine (5 ) was obtained in both enantiomerically pure forms by Amano PS lipase-catal yzed esterification in n-hexane using vinyl acetate as acyl donor. The ster eochemical pathway of the carbonylation reaction was proved by configuratio nal assignments through chemical correlation.