Visible-Light Reductive Cyclization of Nonactivated Alkyl Chlorides

Nonactivated alkyl chlorides are readily available and bench-stable feedstocks; however, they exhibit an inherent chemical inertness, in part, due to their large negative reduction potentials, which have precluded their widespread use as radical precursors in visible-light photocatalysis. Herein, we highlight some recent strategies for activating challenging organic halides under light irradiation, with special emphasis in C(sp³)–halide bonds. In this line, a brief summary of the reactivity of Vitamin B₁₂, F₄₃₀ cofactor and derivatives is required to comprehend the chemistry behind our developed Cu/M (M = Co, Ni) dual catalytic system. Catalyst design has been key for developing a mild and general photoredox methodology for the intramolecular reductive cyclization of nonactivated alkyl chlorides with tethered alkenes. The cleavage of strong C(sp³)–Cl bonds is mediated by a highly nucleophilic low-valent cobalt or nickel intermediate generated by visible-light photoredox reduction employing a copper photosensitizer.