Sulfinate-Salt-Mediated Radical Relay Cyclization of Cyclic Ethers with 2-Alkynylbenzonitriles toward 3-Alkylated 1-Indenones.

A new sulfinate salt-mediated radical relay for the completion of C(sp3 )-H bond indenylation of cyclic ethers with readily available 2-alkynylbenzonitriles by combining silver/tert-butyl peroxide (TBHP) was established, providing a wide range of 3-alkylated 1-indenones with generally good yields. Interestingly, the current reaction system can tolerate an S-centered radical and a C-centered radical in one pot, in which the S-centered radical promotes the formation of the C-centered radical to induce a radical cascade without disturbing the reaction process. A reaction mechanism is also proposed based on control experiments.