2-oxo-3β-(2-phenylacetamido)-4β-mercaptoazetidine

Diazo-((2R,3R)-4-oxo-3-phenylacetylamino-azetidin-2-ylsulfanylcarbonyl)-acetic acid methyl ester

((2R,3R)-4-Oxo-3-phenylacetylamino-azetidin-2-ylsulfanylcarbonyl)-acetic acid methyl ester

2-oxo-bisnorpenicillin G-3-t-butyl carboxylate

2-oxo-bisnorpenicillin G-3-β-(trimethylsilyl)-ethyl carboxylate