benzhydryl (E)-(2S,3S,5R)-3-(2-benzyloxycarbonyl-vinyl)-3-methyl-4,4,7-trioxo-4-thia-1-aza-bicyclo[3.2.0]heptane-2-carboxylate 以54 mg (30%)的产率得到sodium (E)-(2S,3S,5R)-3-(2-benzyloxycarbonyl-vinyl)-3-methyl-4,4,7-trioxo-4-thia-1-aza-bicyclo[3.2.0]heptane-2-carboxylate