Remote Directed Isocyanation of Unactivated C(sp3)-H Bonds: Forging Seven-Membered Cyclic Ureas Enabled by Copper Catalysis.

Reported herein is an unprecedented copper-catalyzed site-selective δ-C(sp3)-H bonds activation of aliphatic sulfonamides for constructing the synthetically useful seven-membered N-heterocycles. A key to success is the use of in-situ-formed amide radicals, to activate the inert C(sp3)-H bond, and inexpensive TMSNCO, as a coupling reagent under mild conditions. To the best of our knowledge, this represents the first use of alkylamine derivatives as a five-membered synthon to prepare a seven-membered N-heterocycles.