Site-Selective Remote Radical C−H Functionalization of Unactivated C−H Bonds in Amides Using Sulfone Reagents

A general and practical strategy for remote site-selective functionalization of unactivated aliphatic C−H bonds in various amides by radical chemistry is introduced. C−H bond functionalization is achieved by using the readily installed N-allylsulfonyl moiety as an N-radical precursor. The in situ generated N-radical engages in intramolecular 1,5-hydrogen atom transfer to generate a translocated C radical which is subsequently trapped with various sulfone reagents to afford the corresponding C−H functionalized amides. The generality of the approach is documented by the successful remote C−N₃, C−Cl, C−Br, C−SCF₃, C−SPh, and C−C bond formation. Unactivated tertiary and secondary C−H bonds, as well as activated primary C−H bonds, can be readily functionalized by this method.