1-Azabicyclo[3.2.0]hept-2-ene-2-carboxylicacid,3-[[(3S,5S)-5-[(dimethylamino)carbonyl]-1-[[(4-nitrophenyl)methoxy]carbonyl]-3-pyrrolidinyl]thio]-6-[(1R)-1-hydroxyethyl]-4-methyl-7-oxo-,(4-nitrophenyl)

3-[[5-[(dimethylamino)carbonypyrrolidinyl]thio]-6-(1-hydroxyethyl)-4-methyl-7-oxo-1-azabicyclo[3.2.0]hept-2-ene-2-carboxylic acid, (4-nitrophenyl)methyl ester ; 3-[[5-[(dimethylamino)carbony pyrrolidinyl] thio]-6-(1-hydroxyethyl)-4-methyl-7-oxo-1-azabicyclo[3.2.0]hept-2-ene-2-carboxylic acid, (4-nitrophenyl)methyl ester ; p-nitrobenzyl(4r,5s,6s)-3-[(3s,5s)-(5-dimethylaminocarbonyl-1-p-nitrobenzyloxycarbonyl)-pyrrolidin-3-ylsulfanyl]-6-((r)-1-hydroxy-ethyl)-4-methyl-7-oxo-1-aza-bicyclo[3.2.0]hept-2ene-4-carboxylate ; meropenem intermediates(e-8,mrpm-pnb) ; protected meropenem ; p-nitrobenzyl(1r,5s,6s)-2-[(3s,5s)-(5-dimethylaminocarbonyl-1-p-nitrobenzyloxycarbonyl)pyrrolidin-3-carboxylate ; 5) protected meropenem ; 4-nitrobenzyl (5s,6s)-3-[((3s,5s)-5-[(dimethylamino)carbonyl]-1-{[(4-nitrobenzyl)oxy]carbonyl}pyrrolidinyl)sulfanyl]-6-[(1r)-1-hydroxyethyl]-4-methyl-7-oxo-1-azabicyclo[3.2.0]hept-2-ene-2-carboxylate ; 3-[[5-[(dimethylamino)carbonyl-pyrrolidinyl]thio]-6-(1-hydroxyethyl)-4-methyl-7-oxo-1-azabicyclo[3.2.0]hept-2-ene-2-carboxylic acid, (4-nitrophenyl)methyl ester