The unsaturated nitrile (III) is prepared by Wittig reaction of 2-(4-chlorobenzoyl)pyridine (I) with phosphorane (II). Subsequent reduction of (III) with NaBH4 in boiling isopropanol provides the saturated nitrile (IV). The cyano group of (IV) is then reduced to amine (V) employing LiAlH4 in refluxing Et2O.

Metalation of 1-trityl-4-iodoimidazole (VI) with ethylmagnesium bromide, followed by addition to 4-cyanobenzaldehyde (VII) gives rise to the carbinol (VIII), which is further reduced to the diaryl methane (IX) employing triibutyltin hydride in the presence of AIBN. Trimethylaluminium-catalyzed coupling between nitrile (IX) and amine (V) provides amidine (X). The N-trityl group of (X) is finally removed under acidic conditions to furnish the title compound.