Diphenyl (4'-aminobiphenyl-4-ylamino)(pyridin-3-yl)methylphosphonate (1) was synthesized in 88% yield from reaction of pyridine-3-carboxaldehyde with benzidine and triphenylphosphite in the presence of titanium tetrachloride as a catalyst. Diazotization of 1 gave the corresponding diazonium salt 2 which was coupled with several hydroxyl or amino compounds to give the corresponding azo dyes 3–8 in 82-88% yields after crystallization.