A new rapid multicomponent domino heteroannulation of heterocyclic keteneaminals: solvent-free regioselective synthesis of functionalized benzo[g]imidazo[1,2-a]quinolinediones

A highly efficient and straightforward three-component cascade reaction was developed to synthesize benzo[g]imidazo[1,2-a]quinolinedione derivatives from heterocyclic ketene aminals (HKAs), aldehydes, and 2-hydroxy-1,4-naphthoquinone (HNQ) via Et(3)N-catalyzed tandem [3 + 2 + 1] annulation under solvent-free conditions. The reactions were very mild, convenient and highly regioselective to form new fused tetracyclic target molecules.