(1E,5R)-3-Phenylmethyl-4-thia-2,6-diazabicyclo[3.2.0]hept-2-en-7-one

(E)-2-((1R,5R)-3-Benzyl-7-oxo-4-thia-2,6-diaza-bicyclo[3.2.0]hept-2-en-6-yl)-3-hydroxy-but-2-enoic acid benzhydryl ester