p. 2531 - 2549
(2007/10/02)1-(o-nitrobenzyloxycarbonyltriphenylphosphoranylidine)methyl-4-(2-pyridylthiocarbonyl)methyl-azetidin-2-one
((S)-2-Carboxymethyl-4-oxo-azetidin-1-yl)-(triphenyl-λ5-phosphanylidene)-acetic acid 2-nitro-benzyl ester
((S)-2-Chlorocarbonylmethyl-4-oxo-azetidin-1-yl)-(triphenyl-λ5-phosphanylidene)-acetic acid 2-nitro-benzyl ester
[(R)-2-(2-Hydroxy-ethyl)-4-oxo-azetidin-1-yl]-(triphenyl-λ5-phosphanylidene)-acetic acid 2-nitro-benzyl ester
1-(o-nitrobenzyloxycarbonyltriphenylphosphoranylidene)methyl-4-(2-pyrrolycarbonyl)methyl-azetidin-2-one