Lewis Acid Catalyzed Benzylic C–H Bond Functionalization of Azaarenes; Addition to Imines and Enones

Abstract

Lewis acid catalyzed benzylic C–H bond functionalization of alkyl-substituted azaarenes is described. The addition to N-tosyl imines proceeded under solvent-free conditions using various Lewis acids. Cu(OTf)₂ was the best Lewis acid, and 1,2-addition proceeded at 60–120 °C, giving products in 23–92% yield. On the other hand, strongly Lewis acidic rare-earth metal triflates, Sc(OTf)₃ and Y(OTf)₃, were essential to promote the 1,4-addition of alkyl-substituted azaarenes to enones, and products were obtained in 60–96% yield.

Key words

nitrogen heterocycles - C–H bond functionalization - enones - imines - Lewis acids

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