Bi(OTf)3-Catalyzed Diastereoselective Three-Component Povarov Reaction of Aminoquinones toward Tetrahydroquinolinequinones

We have developed a Bi(OTf)3-catalyzed three-component Povarov reaction of aminoquinones, aldehydes, and olefins that provides straightforward, one-step access to highly substituted 1,2,3,4-tetrahydroquinolinequinones in isolated yields of up to 96%, with diastereoselectivities ranging from 1.6:1 to >20:1. Mechanistic studies using E- and Z-alkene probes support a stepwise cationic pathway rather than a concerted cycloaddition, which rationalizes the observed stereochemical outcomes. The synthetic utility is further highlighted by subsequent oxidative dehydrogenation to afford quinolinequinone derivatives, a class of molecules of significant biological relevance.