(2S,5R,6S)-6-[(R)-1-(tert-Butyl-dimethyl-silanyloxy)-ethyl]-3-[1-(4-fluoro-benzenesulfonyl)-meth-(Z)-ylidene]-7-oxo-1-aza-bicyclo[3.2.0]heptane-2-carboxylic acid 4-nitro-benzyl ester

(3S,4R)-3-[(R)-1-(tert-Butyl-dimethyl-silanyloxy)-ethyl]-4-(3-trimethylsilanyl-prop-2-ynyl)-azetidin-2-one