The synthesis of a series of quinazolinone derivatives such as 2-thioxoquinazolinones, imidazo[1,2-c]quinazolin-5-amines, and benzimidazo[1,2-c]quinazolin-5-amines, starting from nitro-compounds has been described. This general approach features a easy way for access to the target quinazolinone derivatives. The key cyclization step embraces the formation of a thiourea intermediate, mediated by low-valent titanium, and the other important intermediate was also obtained. A variety of substrates can participate in the process with good yields, making this methodology suitable for library synthesis in drug discovery efforts.