(2S,5R,6R)-6-{2-[2-(2-Benzyloxycarbonylamino-ethoxy)-ethoxy]-ethanesulfonylamino}-3,3-dimethyl-7-oxo-4-thia-1-aza-bicyclo[3.2.0]heptane-2-carboxylic acid methoxymethyl ester

(2S,5R,6S)-6-(1,3-dihydro-1,3-dioxo-2H-isoindol-2-yl)-3,3-dimethyl-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylic acid methyl ester

methoxymethyl 6-β-<(benzyloxycarbonyl)methylsulfonamido>penicillinate

methoxymethyl 6-β-<(p-nitrobenzyloxycarbonyl)methylsulfonamido>penicillinate

(2S,5R,6R)-6-{2-[2-(2-Benzyloxycarbonylamino-ethoxy)-ethoxy]-ethanesulfonylamino}-3,3-dimethyl-4,4,7-trioxo-4λ6-thia-1-aza-bicyclo[3.2.0]heptane-2-carboxylic acid methoxymethyl ester