Palladium-Catalyzed Oxidation and Cyclization of Carbon-Carbon Triple Bonds in Fluorous Media Using Molecular Oxygen

Abstract

An intriguing, facile, and efficient oxidation and cyclization of alkynes catalyzed by Pd(OAc)2 in a fluorous biphasic system of N,N-dimethylacetamide (DMA) and perfluorodecalin directly with molecular oxygen is described, which opens an efficient access to tetrasubstituted furans. Under the optimized conditions, intermolecular reaction between diverse alkynes provides the corresponding mixture of regioisomers with appreciable selectivity. Intramolecular oxidation and cyclization of alkynes are also successfully demonstrated. The reaction proceeds efficiently under mild conditions with atmospheric oxygen as the sole oxidant.