2-((R)-4-(tert-Butyl-dimethyl-silanyloxy)-2-{(2S,3S)-3-[(R)-1-(tert-butyl-dimethyl-silanyloxy)-ethyl]-4-oxo-azetidin-2-yl}-butyrylsulfanylmethyl)-malonic acid diethyl ester

(3S,4R)-3-<(1'R)-1'-<(tert-Butyldimethylsilyl)oxy>ethyl>-4-<(1'R)-1'-(hydroxymethyl)prop-2'-enyl>azetidin-2-one

(S)-{(2R,3S)-2-Allyl-3-[(R)-1-(tert-butyl-dimethyl-silanyloxy)-ethyl]-4-oxo-azetidin-1-yl}-hydroxy-acetic acid ethyl ester

(3S,4R)-3-<(1R)-(tert-butyldimethylsiloxy)ethyl>-4-<3-(p-nitrobenzyloxycarbonylamino)propionylthio>azetidin-2-one

(1S,5R,8aS,8bR)-1-[(R)-1-(tert-Butyl-dimethyl-silanyloxy)-ethyl]-5-methoxy-2-oxo-1,2,5,6,7,8,8a,8b-octahydro-azeto[2,1-a]isoindole-4-carboxylic acid allyl ester