(2S,5R,6S)-benzyl 6-(1,3-dioxoisoindolin-2-yl)-3,3-dimethyl-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate
4-nitrobenzyl 2-diazo-3-oxo-butanoate
(Z)-2-[(2R,3S)-1-((R)-1-Benzyloxycarbonyl-2-methyl-allyl)-3-(1,3-dioxo-1,3-dihydro-isoindol-2-yl)-4-oxo-azetidin-2-ylsulfanyl]-3-hydroxy-but-2-enoic acid 4-nitro-benzyl ester