(5R,6S)-6-((S)-1-Hydroxy-ethyl)-3-[2-(4-nitro-benzyloxycarbonylamino)-ethylsulfanyl]-7-oxo-4-thia-1-aza-bicyclo[3.2.0]hept-2-ene-2-carboxylic acid 4-nitro-benzyl ester

(5R,6S)-6-[(S)-1-(tert-Butyl-dimethyl-silanyloxy)-ethyl]-3-[2-(4-nitro-benzyloxycarbonylamino)-ethylsulfanyl]-7-oxo-4-thia-1-aza-bicyclo[3.2.0]hept-2-ene-2-carboxylic acid 4-nitro-benzyl ester

{(2R,3S)-3-[(S)-1-(tert-Butyl-dimethyl-silanyloxy)-ethyl]-2-[2-(4-nitro-benzyloxycarbonylamino)-ethylsulfanylthiocarbonylsulfanyl]-4-oxo-azetidin-1-yl}-(triphenyl-λ5-phosphanylidene)-acetic acid 4-nitro-benzyl ester

{(2R,3S)-3-[(S)-1-(tert-Butyl-dimethyl-silanyloxy)-ethyl]-2-[2-(4-nitro-benzyloxycarbonylamino)-ethylsulfanylthiocarbonylsulfanyl]-4-oxo-azetidin-1-yl}-hydroxy-acetic acid 4-nitro-benzyl ester

sodium 2-((((4-nitrobenzyl)oxy)carbonyl)amino)ethyl carbonotrithioate