TMK 688 is derived trom the condensation ot 5-(3'-methoxy-4'-hydroxyphenyl)-2,4-pentadienoic acid (IV) and N-aminoethyl 4-diphenylmethoxypiperidine (X) in the presence of ethyl chloroformate in dichloromethane. Synthesis of intermediate (IV): Vanillin (I) is protected with ethyl chloroformate to give (II), which is then treated with triethyl 4-phosphonocrotonate and followed by alkali hydrolysis to produce (IV).

Synthesis of intermediate (X): 4-Hydroxypiperidine (V) is protected with ethyl chloroformate to give (VI), which is then condensed with bromodiphenylmethane in the presence of sodium carbonate yielding (VII). AIkali hydrolysis of (VII) gives (VIII), which is then treated with N-(2-bromoethyl)phthalimide to yield (IX). (IX) is then deprotected by a treatment of 80% hydrazine hydrate, producing (X).