6-Methoxy-3,3-dimethyl-7-oxo-6-phenylacetylamino-4-thia-1-aza-bicyclo[3.2.0]heptane-2-carboxylic acid benzyl ester

benzyl (2S,5R,6R)-6--7-methoxycarbonyl-(E)-methylene-3,3-dimethyl-4-thia-1-azabicyclo<3.2.0>heptane-2-carboxylate

benzyl 6β-[(2,2,2-Trichloroethoxy)carbonylamino]-6α-formamidopenicillanate

benzyl 6β-penicillanate

benzyl 6α-formamido-6β-(2,2,2-trichloroethoxycarbonylamino)penicillanate 1α-oxide