Catalytic Radical Cyclization of Oximes Induced by One-Electron Transfer

Anion radicals generated by one-electron reduction of oxime derivatives act as iminyl radical equivalents. That is, the intramolecular C–N bond formation of γ,δ-unsaturated or β-aryl oximes is induced by one-electron reduction to give various aza-heterocycles. The catalytic electron transfer processes are developed by using hydroquinones or copper reagents as electron donors. Photo-induced electron transfer is also utilized to transform of γ,δ-unsaturated oximes to dihydropyrroles. Total synthesis of peduncularine was achieved by applying the catalytic radical cyclization of oximes as a key step.