Nickel-catalyzed oxidative coupling reactions of two different terminal alkynes using O2 as the oxidant at room temperature: facile syntheses of unsymmetric 1, 3- …
Two different terminal alkynes now can be coupled together in the presence of NiCl2· 6H2O/CuI by using an excess of one of the terminal alkyne substrates. The new method employed 20 mol% TMEDA as the ligand and environmentally benign O2 or air as the oxidant. It is the first example using Ni-salt as catalyst by employing air or O2 as oxidant, which led to efficient heterocoupling of two different alkynes.