Concise two-step solution phase syntheses of four novel dihydroquinazoline scaffolds

Novel two-step solution phase protocols for the synthesis of dihydroquinazolines and fused dihydroquinazoline-benzodiazepine tetracycles are reported. The methodology employs the Ugi reaction to assemble the desired diversity and acid treatment enables ring-closing transformations. The protocols are further facilitated by the use of microwave irradiation and n-butyl isocyanide to control the rate of each ring-forming transformation.