Gold Catalyzed [3+2] Oxidative Annulation of 1,3‐Enyne with Indole

Abstract

An efficient new method has been developed for the synthesis of ketone‐integrated cyclopentene‐fused indoline derivatives with a high regioselectivity through gold‐catalyzed oxidative cyclo‐coupling of 1,3‐enynes with indoles by using 2,6‐dichloropyridine N‐oxide as the terminal oxidant. A plausible mechanism has been proposed, in which, a cascade process of nucleophilic trapping of the vinyl gold carbene surrogate with indole followed by the subsequent intramolecular cyclization provides the dearomative formal [3+2] cycloaddition product. In addition, a scale‐up reaction and further derivation via cyclopentene’s epoxidation & hydrazone derivative’s 1,5‐ electrocyclization have been performed.