Abstract: Quinazoline is an important heterocyclic compound which has potential biological and pharmaceutical activities. It was reported that benzimidazo[1,2-c]quinazoline derivatives have a high anticancer activity. In this paper, a series of benzimidazo[1,2-c]quinazoline derivatives such as benzimidazo[1,2-c]quinazoline, 5,6-dihydrobenzimidazo[1,2-c]quinazoline and benzimidazo[1,2-c]quinazolin-5-one were synthesized via the reaction of 2-(o-nitrophenyl)benzimidazoles with triethyl orthoformate or acetone or triphosgene promoted by the low-valent titanium reagent(TiCl₄-Zn system). The products were characterized via IR, ¹H NMR, MS and elemental analysis. The structure of compound 4c was confirmed by X-ray single crystal diffraction. A possible reaction mechanism was put forward in this paper. This new method possesses the advantages of easily accessible starting materials, convenient manipulation and high yields.

Key words: Low-valent titanium, Benzimidazo[1,2-c]quinazoine, 2-(o-Nitrophenyl)benzimidazole