Patent ID: 8278477

Claim:
A method for making 2,3-bismethoxycarbonyl-4-phenyl-5-arylhydrazono-cyclopenta-1,3-dienyltriphenylphosphonium, comprising the steps of: adding 3-oxo-3-phenyl-2-(arylhydrozono)propanal to dimethyl acetylenedicarboxylate in dichloromethane at room temperature to form an intermediate; after cyclization of the intermediate, adding triphenylphosphine to the mixture to form crude 2,3-bismethoxycarbonyl-4-phenyl-5-arylhydrazono-cyclopenta-1,3-dienyltriphenylphosphonium; and recrystallizing the crude 2,3-bismethoxycarbonyl-4-phenyl-5-arylhydrazono-cyclopenta-1,3-dienyltripbenylphosphonium to recover pure product.