(4R,5R,6S)-3-(Diphenoxy-phosphoryloxy)-6-(1-hydroxy-ethyl)-4-methyl-7-oxo-1-aza-bicyclo[3.2.0]hept-2-ene-2-carboxylic acid 4-nitro-benzyl ester
(4R,5S,6S)-6-(1-Hydroxy-ethyl)-4-methyl-3-[(S)-1-(4-nitro-benzyloxycarbonyl)-pyrrolidin-3-ylsulfanyl]-7-oxo-1-aza-bicyclo[3.2.0]hept-2-ene-2-carboxylic acid 4-nitro-benzyl ester
ethyl acetimidate hydrochloride
(4R,5S,6S)-6-(1-Hydroxy-ethyl)-4-methyl-7-oxo-3-((S)-pyrrolidin-3-ylsulfanyl)-1-aza-bicyclo[3.2.0]hept-2-ene-2-carboxylic acid
(4S,5R,6S)-3-(Diphenoxy-phosphoryloxy)-6-(1-hydroxy-ethyl)-4-methyl-7-oxo-1-aza-bicyclo[3.2.0]hept-2-ene-2-carboxylic acid 4-nitro-benzyl ester