(S)-2-{(2R,3S)-3-[(R)-1-(tert-Butyl-dimethyl-silanyloxy)-ethyl]-1-[chloro-(4-nitro-benzyloxycarbonyl)-methyl]-4-oxo-azetidin-2-ylsulfanylcarbonyl}-pyrrolidine-1-carboxylic acid 4-nitro-benzyl ester

(R)-Pyrrolidine-1,2-dicarboxylic acid 1-(4-nitro-benzyl) ester

(3S,4R)-3-<(1R)-(tert-butyldimethylsiloxy)ethyl>-4-<(2R)-N-p-nitrobenzyloxycarbonylpyrrolidin-2-yl>carbonylthioazetidin-2-one