Site‐Selective Pd‐Catalyzed C(sp³)−H Arylation of Heteroaromatic Ketones

Abstract

A ligand-controlled site-selective C(sp 3 )À H arylation of heteroaromatic ketones has been developed using Pd catalysis. The reaction occurred selectively at the αor βposition of the ketone side-chain. The switch from αto βarylation was realized by addition of a pyridone ligand. The αarylation process showed broad scope and high site-and chemoselectivity, whereas the β-arylation was more limited. Mechanistic investigations suggested that α-arylation occurs through CÀ H activation/oxidative addition/reductive elimination whereas β-arylation involves desaturation and aryl insertion.