Tandem Pd-catalyzed annulation/coupling of acetylenic enamines with aryl triflates

Abstract

A cascade of 5-exo-dig intramolecular nucleophilic addition of enamine to terminal alkyne followed by cross coupling has been demonstrated for the first time. Two new C–C bonds are stereoselectively forged by a single Pd-complex capable of catalyzing two mechanistically diverse transformations. Mechanistic investigations identified cyclization as the rate limiting step relying on the facile displacement of OTf, weakly bound to the Pd-center, by the alkyne.