p-nitrobenzyl 2-<(3S,4R)-3-<(1R)-(tert-butyldimethylsiloxy)ethyl>-4-<<(2R)-N-p-nitrobenzyloxycarbonylpyrrolidin-2-yl>carbonylthio>-2-oxoazetidin-1-yl>-2-triphenylphosphoranylideneacetate

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

(2S,5R,6S)-6-Bromo-6-[1-(tert-butyl-dimethyl-silanyloxy)-ethyl]-3,3-dimethyl-7-oxo-4-thia-1-aza-bicyclo[3.2.0]heptane-2-carboxylic acid methyl ester

(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

p-nitrobenzyl 2-<(3S,4R)-3-<(1R)-(tert-butyldimethylsiloxy)ethyl>-4-<<(2S)-N-p-nitrobenzyloxycarbonylpyrrolidin-2-yl>carbonylthio>-2-oxoazetidin-1-yl>-2-hydroxyacetate