Selective Piperidine Synthesis Exploiting Iodine-Catalyzed C<sub>sp</sub><sup>3</sup>–H Amination under Visible Light

2017-05-10T00:00:00Z (GMT) by Hongwei Zhang Kilian Muñiz
A route to selective piperidine formation through intramolecular catalytic C<sub>sp</sub><sup>3</sup>–H amination is described. This hydrocarbon amination reaction employs a homogeneous iodine catalyst derived from halogen coordination between molecular iodine and a terminal oxidant. It relies on visible light initiation and proceeds within two catalytic cycles that comprise a radical C–H functionalization and an iodine-catalyzed C–N bond formation. Under these conditions, the commonly observed preference for pyrrolidine synthesis based on halogenated nitrogen intermediates within the Hofmann–Löffler domain is effectively altered in favor of a free-radical-promoted piperidine formation. The protocol is demonstrated for a total of 30 applications.