(S)-6-{(2R,3S)-3-[(R)-1-(tert-Butyl-dimethyl-silanyloxy)-ethyl]-4-oxo-azetidin-2-yl}-cyclohex-1-enecarboxylic acid ethyl ester

(3S,4R)-3-<(1R)-1-tert-butyldimethylsilyloxyethyl>-4-<(1S)-2-phenylselenenylmethylcyclohex-2-enyl>-2-azetidinone

(3S,4R)-3-<(1R)-1-tert-butyldimethylsilyloxyethyl>-4-<(1R,3S)-3-triethylsilyloxy-2-oxocyclohexyl>-1-(2-diphenylmethoxycarbonyl-1-hydroxyethyl)-2-azetidinone

(3S,4R)-3-<(1R)-1-tert-butyldimethylsilyloxyethyl>-4-<(1R,3S)-3-triethylsilyloxy-2-oxocyclohexyl>-1-(diphenylmethoxycarbonyl-triphenylphosphoranylidenemethyl)-2-azetidinone