2,5-Bis(p-bromophenyl)furan (II) was prepared by cyclodehydration of diketone (I) in refluxing acetic anhydride. Displacement of both bromine atoms by copper(I) cyanide in boiling quinoline generated the dicyano derivative (V). Alternatively, furan (V) was prepared by addition of p-cyanobenzaldehyde (III) to divinyl sulfone (IV) in the presence of a thiazolium catalyst. After conversion of the cyano groups of (V) into bis-imidate (VI), reaccion with ethanolic ammonia furnished amidine (VII). The stable symmetrical carbonate (X) was obtained by reaction of p-fluorophenyl chloroformate (VIII) with p-fluorophenol (IX) in the presence of pyridine. Finally, reaction of the bis(amidine) compound (VII) with carbonate (X) yielded the title compound.
The Friedel Crafts condensation of fumaryl chloride (I) with bromobenzene (II) gives 1,2-bis(4-bromobenzoyl)ethylene (III), which is reduced with Zn and Ac-OH to yield 1,4-bis(4-bromophenyl)butane-1,4-dione (IV). The cyclization of (IV) in refluxing Ac2O affords 2,5-bis(4-bromophenyl)furan (V) which is treated with CNCu in refluxing quinoline to provide 2,5-bis(4-cyanophenyl)furan (VI). The reaction of (VI) with HCl in ethanol gives the bis imidate (VII), which is finally treated with ammonia in ethanol to yield the target bis benzamidine.