(3S,4S)-3-[(R)-1-(tert-butyldimethylsilyloxy)ethyl]-4-[1,1-di(allyloxycarbonyl)ethyl]-2-azetidinone

HO2CCH(CH3)CO2All

allyl 1-benzoyl-3-methyl-2-oxopiperidine-3-carboxylate

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

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