Synthesis and basicity of 4-(N,N-dimethylamino)-2-arylquinazolines

The reaction of substituted N-phenylbenzimidoyl chlorides with N,N-dimethylcynanamide in the presence of titanium tetrachloride has yielded seven 4-(N,N-dimethylamino)-2-arylquinazolines substituted on the phenyl ring with electron donating or withdrawing groups. pKa values have been determined for these compounds and analyzed in conjunction with the Hammett sigma constants to observe the influence of these phenyl substituents upon the basicity of 4-(N,N-dimethylamino)-2-arylquinazolines. The rho value, single crystal X-ray analysis and N-15-nmr spectra give evidence about the preferential site of protonation in such systems.