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.