(3S,4R)-1-<<(allyloxy)carbonyl>hydroxymethyl>-3-<(1R)-1-<(tert-butyldimethylsilyl)oxy>ethyl>-4-<(1R)-1-<<(tert-butyldimethylsilyl)oxy>carbonyl>ethyl>azetidin-2-one

tert-butyldimethylsilyl (2R)-2-((2S,3S)-1-(2-(allyloxy)-1-chloro-2-oxoethyl)-3-((R)-1-((tert-butyldimethylsilyl)oxy)ethyl)-4-oxoazetidin-2-yl)propanoate

(R)-2-{(2S,3S)-1-[Allyloxycarbonyl-(triphenyl-λ5-phosphanylidene)-methyl]-3-[(R)-1-(tert-butyl-dimethyl-silanyloxy)-ethyl]-4-oxo-azetidin-2-yl}-propionic acid