Povarov-type reaction using methyl as new input: direct synthesis of substituted quinolines by I2-mediated formal [3 + 2 + 1] cycloaddition.

A highly efficient molecular iodine mediated formal [3 + 2 + 1] cycloaddition reaction for the direct synthesis of substituted quinolines from methyl ketones, arylamines, and styrenes is developed. The methyl group of the methyl ketone represents uniquely reactive input in the Povarov reaction. A self-sequenced iodination/Kornblum oxidation/Povarov/aromatization mechanism has been proposed as a possible reaction sequence to account for the results observed in this study.