6β-benzyloxycarbonylamino-1ξ-oxo-1λ4-penicillanic acid methyl ester

(3R,4S)-3-(benzyloxycarbonylamino)-4-(1'-oxo-ethyl)-azetidin-2-one

((2S,3S)-2-Acetoxy-3-benzyloxycarbonylamino-4-oxo-azetidin-1-yl)-oxo-acetic acid methyl ester

methyl (3S,5R,6R)-6-benzyloxycarbonylamino-2,2-dimethylpenam-3-carboxylate

(2R) methyl 2-((3S,4S)-4-acetoxy-3-benzyloxycarbonylaminoazetidin-2-on-1-yl)-3-methylbut-3-enoate