A Simple and Efficient One-Pot Synthesis of Substituted Benzo[b]furans by Sonogashira Coupling-5-endo-dig Cyclization Catalyzed by Palladium Nanoparticles in Water Under Ligand- and Copper-Free Aerobic Conditions

摘要

A simple and efficient procedure for the synthesis of 2-substi-tuted benzofb]furan derivatives has been developed by the reaction of 2-iodophenols and arylacetylenes in water catalyzed by palladium nanoparticles generated in situ in open air. The reaction does not require any additive, ligand, or co-catalyst. The reaction occurs through Sonogashira coupling of 2-iodophenols with phenylacetylenes followed by 5-endo-dig cyclization. A series of functionalized benzo[b]furan derivatives was obtained in high yields by this procedure.