Visible-Light-Promoted Carboimination of Unactivated Alkenes for the Synthesis of Densely Functionalized Pyrroline Derivatives

An efficient strategy which integrates visible-light-induced iminyl-radical formation with carboimination of unactivated alkenes has been developed for the easy access of densely functionalized pyrroline derivatives. With fac-[Ir(ppy)3] as photoredox catalyst, the acyl oximes were converted into iminyl radical intermediates by one electron reduction, and evolve through a cascade of intramolecular cyclization and intermolecular carbon radical trapping to give the functionalized pyrrolines. The utilization of silyl enol ethers as coupling partners not only allows the introduction of synthetically useful ketone functionalities but also renders catalyst regeneration without any external reductants. This protocol is characterized by its mild reaction conditions and the tolerance of a broad range of functionalities.