Copper‐Catalyzed Synthesis of 5‐Arylindolo[1,2‐c]quinazolin‐6(5H)‐ones from 2‐(2‐Bromoaryl)indoles and Aryl Isocyanates under Microwave Irradiation

Abstract

Abstract2‐(2‐Bromoaryl)indoles react with aryl isocyanates by microwave irradiation in the presence of catalytic CuI along with a base to afford 5‐arylindolo[1,2‐c]quinazolin‐6(5H)‐ones. The reaction is compatible with 2‐(2‐bromoaryl)indoles bearing straight and branched alkyl chains at position 3 of indole moiety. Both electron‐donating and ‐withdrawing substituents on bromophenyl and indole moieties are well tolerated. The reaction proceeds through an initial nucleophilic addition of 2‐(2‐bromoaryl)indoles to aryl isocyanates. This is followed by an intramolecular C−N bond formation by an addition‐elimination nucleophilic aromatic substitution via Meisenheimer complexes and a copper‐catalyzed Ullmann‐type coupling.