Homocoupling of Terminal Alkynes Catalysed by Ultrafine Copper Nanoparticles on Titania

Copper nanoparticles on titania effectively catalyse the oxidative homocoupling of terminal alkynes in the presence of piperidine as a base in tetrahydrofuran (THF) or under solvent-free conditions. A wide range of diynes have been synthesised in high yields using low catalyst loading (1 mol-% Cu). The copper catalyst (mainly as Cu2O) has been characterised by different means, is easy to prepare, can be reutilised several times, works either in air or under inert atmosphere and was shown to be superior to other commercially available copper sources.