Copper‐Catalyzed A3‐Coupling: Synthesis of 3‐Amino‐1,4‐diynes

Cu‐catalyzed A 3 (amine, aldehyde, and alkyne) coupling reactions were investigated for the synthesis of 3‐amino‐1,4‐diynes. Although metal‐catalyzed A 3 ‐coupling reactions have been extensively used to synthesize various propargylamines, the A 3 ‐coupling for the synthesis of 3‐amino‐1,4‐diynes has been rarely reported. In this study, various symmetrical 3‐amino‐1,4‐diynes were synthesized by the sequential Cu‐catalyzed dealkynylation of propargyl aldehydes followed by A 3 ‐coupling. Unsymmetrical 3‐amino‐1,4‐diynes were also synthesized in 49–85 % yields by Cu‐catalyzed A 3 ‐coupling.