Synthesis of Isoquinolines and Heterocycle-Fused Pyridines via Three-Component Cascade Reaction of Aryl Ketones, Hydroxylamine, and Alkynes

An efficient one-pot synthesis of isoquinolines and heterocycle-fused pyridines by three-component reaction of aryl ketones, hydroxylamine, and alkynes is developed. The reaction involves condensation of aryl ketones and hydroxylamine, rhodium­(III)-catalyzed C–H bond activation of the in situ generated aryl ketone oximes, and cyclization with internal alkynes. This protocol enables rapid assembly of multisubstituted isoquinolines as well as γ-carbolines, furo­[2,3-c]­pyridines, thieno­[2,3-c]­pyridines, and benzofuro­[2,3-c]­pyridines from readily available substrates.