Copper-Catalyzed Oxidative Diamination of Terminal Alkynes by Amidines: Synthesis of 1,2,4-Trisubstituted Imidazoles

An efficient copper-catalyzed synthesis of 1,2,4-trisubstituted imidazoles using amidines and terminal alkynes has been developed. Overall, the oxidative process, which involves Na2CO3, pyridine, a catalytic amount of CuCl2·2H2O, and oxygen (1 atm), consisted of a regioselective diamination of alkynes allowing the synthesis of diverse imidazoles in modest to good yields.