Photoredox Approach to <i>N</i>‑Acyl-<i>N′</i>-aryl‑<i>N</i>,<i>N′</i>-aminals Using Enamides and Their Conversion to γ‑Lactams

A photoredox catalytic approach to synthetically valuable <i>N</i>-acyl-<i>N</i>′-aryl-<i>N</i>,<i>N</i>′-aminals is described. This method uses the addition of a radical precursor to enamides, with subsequent interception of the cationic iminium intermediate with an arylamine. The reaction has been shown to be compatible with electron-rich and electron-deficient arylamines, and moderate to good levels of diastereoselectivity can be attained using a chiral enamide. Furthermore, the <i>N</i>-acyl-<i>N</i>′-aryl-<i>N</i>,<i>N</i>′-aminal reaction products can be readily cyclized, providing a novel synthetic route to valuable γ-lactams