(3S,4R)-1-(tert-Butyl-dimethyl-silanyl)-3-[(R)-1-(tert-butyl-dimethyl-silanyloxy)-ethyl]-4-{(1R,4R)-4-[2-(tert-butyl-dimethyl-silanyloxy)-ethyl]-2-oxo-cyclohexyl}-azetidin-2-one

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