Synthesis of Benzo[4,5]imidazo[1,2‑c]pyrimidin-1-amines and Their Analogs via Copper-Catalyzed C–N Coupling and Cyclization

2-(2-Bromovinyl)­benzimidazoles and 2-(2-bromophenyl)­benzimidazoles react with cyanamide by microwave irradiation in dimethylformamide in the presence of a catalytic amount of CuI along with a base to give the corresponding benzo­[4,5]­imidazo­[1,2-c]­pyrimidin-1-amines and benzo­[4,5]­imidazo­[1,2-c]­quinazolin-6-amines, respectively, in moderate to good yields. 2-(2-Bromophenyl)­indoles also react with cyanamide under similar conditions to afford indolo­[1,2-c]­quinazolin-6-amines. The reaction pathway seems to proceed via a sequence such as intermolecular C–N coupling, C–N formative cyclization, and tautomerization.