An alternative CuCl–piperidine‐catalyzed oxidative homocoupling of terminal alkynes affording 1,3‐diynes in air

Abstract

CuCl with the use of a catalytic amount of piperidine as additive shows high catalytic activity for the oxidative homocoupling reactions of terminal alkynes in toluene at 60• C in air to afford 1,3-diynes in high yields.

Aerobic Copper-Catalyzed Organic Reactions

“…119 High yields were obtained for a variety of substrates, although higher temperatures were necessary in comparison to classical conditions. In an effort to identify a “greener” modification of the Hay coupling, Chen and coworkers reported solvent-free conditions, using just 3 mol% CuCl and 3 mol% pyridine in air.…”

Toward a mechanistic understanding of oxidative homocoupling: the Glaser–Hay reaction

“…[9][10][11][12] In most experiments, a ligand excess or an external base is added because it has been demonstrated that the reaction is faster under basic conditions. Different bases ranging from ammonium hydroxide employed by Glaser to organic amines [11][12][13] (e.g. piperidine, NEt 3 , etc.)…”

Copper‐catalyzed homo‐ and cross‐coupling reactions of terminal alkynes in ethyl lactate

“…On the basis of the originally employed palladium/copper and other bicatalyst systems for oxidative couplings of terminal alkynes, numerous efforts have been made to explore easy, low‐cost and efficient new procedures to run these reactions. The employment of a single alternative transition metal catalyst such as palladium, copper, nickel and cobalt in the reactions has been found to be an improved protocol in terms of atom economics. In addition, discovering new oxidants constitutes another frontier of the modern Glaser reaction.…”