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.