Versatile Electrochemical Synthesis of Selenylbenzo[b]Furan Derivatives Through the Cyclization of 2-Alkynylphenols

Abstract

We report an electrochemical oxidative intramolecular cyclization reaction between 2-alkynylphenol derivatives and different diselenides species to generate a wide variety of substituted-benzo[b]furans. Driven by the galvanostatic electrolysis assembled in an undivided cell, it provided efficient transformation into oxidant-, base-, and metal-free conditions in an open system at room temperature. With satisfactory functional group compatibility, the products were obtained in good to excellent yields.

Electrochemical difunctionalization of alkenes and alkynes for the synthesis of organochalcogens involving C–S/Se bond formation

“…In 2022, an electrochemical oxidative intramolecular cyclization reaction of 2-alkynylphenol derivatives and diselenides under mild conditions has been realized by Braga and co-workers (Scheme 54). 69 This annulation protocol provided an efficient method to synthesize various selenylbenzo[b]furans in good to excellent yields with satisfactory functional group compatibility. Of note, the transformation is not limited to 2-alkynylphenols, and the methoxy-2-(phenylethynyl) benzene was also tolerated well and smoothly converted to the desired product in good yield under the same reaction conditions.…”

A Comprehensive Review on Benzofuran Synthesis Featuring Innovative and Catalytic Strategies

“…The Doerner group 111 reported the synthesis of benzofuran derivatives by employing electrochemical conditions. They carried out the cyclization of 2-alkynylphenols 117 and various diselenides 116 in the presence of platinum electrodes using acetonitrile as the solvent, thereby providing substituted benzofuran heterocycles 118 in high yields.…”

Recent progress in the electrochemical selenofunctionalization of alkenes and alkynes

“…In the same year, the group of Braga also reported an electrochemical oxidative intramolecular cyclization of 2-alkynylphenol with diselenides to access selenated benzo[ b ]furans (Scheme 39). 93 The reaction was carried out in an undivided cell equipped with platinum electrodes, and n Bu 4 NClO 4 as the supporting electrolyte in CH 3 CN. In addition to 2-alkynylphenol, 2-alkynylanisole yielded the corresponding furans with yields of up to 78% under the same reaction conditions.…”