Copper-catalyzed oxidative diamination of terminal alkynes by amidines: synthesis of 1,2,4-trisubstituted imidazoles.
Résumé
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.