[(2R,3S)-3-((R)-1-Hydroxy-ethyl)-2-((1R,3S)-3-hydroxy-2-oxo-cyclohexyl)-4-oxo-azetidin-1-yl]-(triphenyl-λ5-phosphanylidene)-acetic acid benzhydryl ester

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

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

benzhydryl (4S,8S,9R,10S)-4-hydroxy-10-<(1R)-1-hydroxyethyl>-11-oxo-1-azatricyclo-<7.2.0.03,8>undec-2-ene-2-carboxylate

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