Carbonylation Chemistry Applied to the Synthesis of Benzimidazo[2,1‐b]quinazolin‐12‐ones

A carbonylative route towards the synthesis of benzimidazo[2,1‐b]quinazolin‐12‐ones was developed. The key step in this strategy consists of an intramolecular carbonylative lactam formation, starting from N‐(2‐bromophenyl)‐1H‐benzimidazol‐2‐amines. These precursor molecules were synthesized by two different methods to introduce a variety of substituents on the aromatic ring systems. Interestingly, only near‐stoichiometric amounts of carbon monoxide were required in the ring‐closing aminocarbonylation reaction, rendering the developed strategy also suitable for late‐stage 13C‐isotopic labelling. A new synthetic route towards benzimidazo[2,1‐b]quinazolin‐12‐ones has been developed, which relies on the Pd‐catalyzed intramolecular aminocarbonylation of N‐(2‐bromophenyl)‐1H‐benzimidazol‐2‐amines. Using near stoichiometric amounts of 13CO, isotopically labelled benzimidazo[2,1‐b]quinazolin‐12‐ones were synthesized.