Iminyl-Radicals by Oxidation of -Imino-oxy Acids: Photoredox-Neutral Alkene Carboimination for the Synthesis of Pyrrolines

The visible-light-promoted decarboxylation of -imino-oxy propionic acids for the generation of iminyl radicals has been accomplished through the use of Ir(dFCF(3)ppy)(2)(dtbbpy)PF6 as a photoredox catalyst. Different from visible-light-promoted homolysis and single-electron reduction of oxime derivatives, this strategy provides a novel catalytic cycle for alkene carboimination through a sequence comprising N-radical generation, iminyl radical cyclization, intermolecular conjugate addition to a Michael acceptor, and single-electron reduction to afford various pyrroline derivatives in an overall redox-neutral process. The indolizidine alkaloid skeleton could be easily constructed from a pyrroline derivative prepared by this synthetic method.