1-(Ethoxycarbonyl)ethylidenetriphenylphosphorane 5717-37-3 Ethyl 2-(triphenylphosphoranylidene)propanoate Ethyl 2-(triphenylphosphoranylidene)propionate NSC76468 Propanoic acid, 2-(triphenylphosphoranylidene)-, ethyl ester Propionic acid, 2-(triphenylphosphoranylidene)-, ethyl ester