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(2007/10/02)Pivaloyloxymethyl (2S,5R,6S)-3,3-dimethyl-6-(2-methyl-allyl)-7-oxo-4-thia-1-azabicyclo<3.2.0>heptane-2-carboxylate
6α-bromopenicillanic acid pivalolyloxymethyl ester
3-Methyl-2-[(3S,4R)-3-(2-methyl-allyl)-2-oxo-4-phenylacetylsulfanyl-azetidin-1-yl]-but-2-enoic acid 2,2-dimethyl-propionyloxymethyl ester