ZK-807834 is obtained by condensation of the diaryl ether (I) with the phenol (II) by means of K2CO3 to afford the bisaryl ether (III). Reaction of the cyano group of (III), first with HCl in ethanol and then with ammonia, yields the corresponding amidino compound (IV), which is finally demethylated with HBr.
Coupling of 4-methyl-2,3,5,6-tetrafluoropyridine (I) with two molecules of 3-hydroxybenzonitrile (II) in the presence of NaH in hot DMF produced the 2,6-bis(phenoxy)pyridine (III). Conversion of the nitrile groups of (III) into the target bisamidine was then achieved by formation of the corresponding imidate (IV) with ethanol and HCl, followed by treatment with ethanolic ammonia at 60 C in a sealed tube.