<i>In Situ</i> Cu Nanoparticle Deposition on a Graphite Felt Cathode Enabling Diverse Electrochemical Oxidative Functionalization Cyclization of Alkynes

We developed a novel in situ Cu nanoparticle deposition on a graphite felt cathode for enabling diverse electrochemical oxidative functionalization cyclization reactions of alkynes. Two series of trifluoromethylated and phenylsulfonylated dioxodibenzothiazapine derivatives were produced in good to high yields. This protocol features simple and high efficiency, good regioselectivity, mild conditions, and a broad scope and good compatibility of substrates in one pot. Also, the role of the in situ modified Cu@GF electrode was studied in depth by a variety of determination methods and some control experiments through using an H-type electrolytic cell with a Nafion 117 diaphragm, and a plausible electrochemical oxidative reaction mechanism was proposed. Moreover, the electrochemical reaction system could be recycled for at least four times with no obvious efficiency reduction, representing its sustainability. This strategy of cathode modification for accelerating anodic electrochemical oxidative reactions would provide a sustainable and alternative route for the electrochemical transformations inaccessible by traditional chemical reactions.