Selective Piperidine Synthesis Exploiting Iodine-Catalyzed C_sp³–H Amination under Visible Light

Abstract

A route to selective piperidine formation through intramolecular catalytic Csp3–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.