Highly Efficient Copper‐Catalyzed Synthesis of Internal Alkynes via Aerobic Oxidative Arylation of Terminal Alkynes

Abstract We have developed a novel and highly efficient, copper‐catalyzed synthesis of internal alkynes via oxidative couplings of aromatic boronic acids with terminal alkynes at room temperature. The protocol uses inexpensive copper(I) oxide [Cu 2 O] as the catalyst, oxygen in the air as the stoichiometric oxidant; no ligand and sealed reaction vessels are required, and remarkable functional group tolerability is observed with coupling occurring.