p-nitrobenzyl (5R,6S)-6-<(1R)-(tert-butyldimethylsiloxy)ethyl>-2-<((RS)-N-p-nitrobenzyloxycarbonylpiperidin-2-yl)methyl>-2-penem-3-carboxylate

(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