Synergistic I2/Amine Promoted Povarov-Type Reaction for the Synthesis of 2-Acyl-3-aryl(alkyl)quinolines Using Aryl(alkyl)acetaldehydes as Alkene Surrogates

A synergistic I2/amine promoted formal [4 + 2] cycloaddition of methyl ketones, arylamines, and aryl(alkyl)acetaldehydes as alkene surrogates has been established. This protocol allowed the modular synthesis of various 2-acyl-3-aryl(alkyl)quinolines, rather than 2,4-substituted quinolines. Notably, the arylamines not only participated as reactants in this reaction but also acted as indispensable catalysts to promote enamine formation. Moreover, mechanistic investigation suggested that the reaction occurred via an iodination/Kornblum oxidation/Povarov/aromatization sequence.