(5R)-6β-[(R)-1-Hydroxyethyl]-3-[[2-[[[(4-nitrophenyl)methoxy]carbonyl]amino]ethyl]thio]-7-oxo-1-azabicyclo[3.2.0]hept-2-ene-2-carboxylic acid (4-nitrophenyl)methyl ester

(4-nitrophenyl)methyl [5R-[5alpha,6alpha(R*)]]-6-(1-hydroxyethyl)-3-[[2-[[[(4-nitrophenyl)methoxy]carbonyl]amino]ethyl]thio]-7-oxo-1-azabicyclo[3.2.0]hept-2-ene-2-carboxylate