Synthesis of Aryl Alkynes via Copper Catalyzed Decarboxylative Alkynylation of 2-Nitrobenzoic Acids.

An efficient protocol for the synthesis of internal aryl alkynes was achieved via Cu-catalyzed decarboxylative cross-coupling reactions, and to the best of our knowledge, this is the first example of a Cu-catalyzed decarboxylative alkynylation of benzoic acids with terminal alkynes. This approach utilizes simple Cu salt as catalyst and O2, an abundant, clean, and green material, as the oxidant. The reaction tolerates various functional groups, and a variety of internal aryl alkynes were synthesized in 46-83% yields.