ethyl 4-cyclobutyl-3-oxo-2-(triphenylphosphoranylidene)butanoate

ethyl 8-bromo-3-oxo-2-(triphenylphosphoranylidene)-4(E)-octenoate

ethyl 8-iodo-3-oxo-2-(triphenylphosphoranylidene)-4(E)-octenoate

3-((1R,2R)-2-Butyl-cyclopentyl)-3-oxo-2-(triphenyl-λ5-phosphanylidene)-propionic acid ethyl ester