Selective C–C coupling of terminal alkynes under an air atmosphere without base over Cu–NX–C catalysts†
Abstract
The fabrication of a silk fibroin-drived porous, in situ nitrogenated carbon skeleton with highly dispersed Cu–NX–C active sites via a sol–gel and pyrolysis treatment was demonstrated. Cu–NX–C was used to catalyze the oxidative homo-coupling of terminal alkynes with excellent functional group tolerance and high yields under an air atmosphere without base and additives. The small amount of catalyst (2 mol%) and suitable recyclability further demonstrated its good activity and stability. The excellent activity of the Cu–NX–C catalyst can be ascribed to its high surface area, porous structure, small size of the highly dispersed Cu–NX–C active sites and graphitic N. A possible mechanism was deduced according to the structural and surface valence analyses of the sample before and after the reaction. The report aims to demonstrate that such a nature-based sustainable catalyst can provide new insights into the design of coupling reaction catalysts with outstanding catalytic C–C coupling performance.