Merging " Anti-Baldwin" 3- Exo-Dig Cyclization with 1,2-Alkynyl Migration for Radical Alkylalkynylation of Unactivated Olefins.

A new combination of " anti-Baldwin" 3- exo-dig cyclization with 1,2-alkynyl migration of 1,4-enynes with simple cycloalkanes was established, enabling C-C breaking and reconstruction to access a wide range of α-alkynyl ketones with generally good yields by FeCl2/di- tert-butyl peroxide (DTBP) as a catalytic oxidation system. Radical-induced C(sp3)-H functionalization of cycloalkanes was realized, leading to the direct formation of C(sp3)-C(sp3) and C(sp)-C(sp3) bonds. The mechanism for forming α-alkynyl ketones was proposed.