192049-49-3 4-Thia-2,6-diazabicyclo[3.2.0]hept-2-ene-6-acetic acid,a-(1-methylethylidene)-7-oxo-3-(phenylmethyl)-,(4-nitrophenyl)methyl ester,(1R,5R)- 4-Thia-2,6-diazabicyclo[3.2.0]hept-2-ene-6-acetic acid,a-(1-methylethylidene)-7-oxo-3-(phenylmethyl)-,(4-nitrophenyl)methyl ester,(1R,5R)-