An efficient synthesis of quinazoline derivatives with the aid of low-valent titanium reagent

Quinazolin-4(3H)-ones, 1,2-dihydroquinazolin-4(3H)-ones, 3,4-dihydroquinazolines, imidazo[1,2-c]quinazolines and 5,6-dihydroimidazo[1,2-c]quinazolines were synthesized by the novel reductive reaction of nitro group, N-H bond and ortho-ester, aldehydes or ketones promoted by the low-valent titanium reagent (TiCl4-Zn system). The structures of these compounds were characterized by elemental analysis, IR and (HNMR)-H-1 spectra and further confirmed by single crystal X-ray diffraction analysis.