Copper-Mediated Intramolecular Oxidative C–H/C–H Cross-Coupling of α‑Oxo Ketene N,S‑Acetals for Indole Synthesis

CuCl2-mediated intramolecular C–H/C–H cross-dehydrogenative coupling (CDC) of thioalkyl-substituted α-acetyl or α-aroyl ketene N,S-acetals afforded 2-thioalkyl indoles. Tunable C–S bond transformations of the resultant indoles led to highly functionalized N-heterocyclic compounds. A β-thioalkyl is necessary to activate the N,S-acetal substrate and enable the CDC reaction to occur, and the relevant mechanism studies revealed that the CDC reaction follows a radical pathway.