benzhydryl (E)-(2S,3S,5R)-3-(2-benzyloxycarbonyl-vinyl)-3-methyl-7-oxo-4-thia-1-aza-bicyclo[3.2.0]heptane-2-carboxylate 以255 mg (30%)的产率得到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