Abstract
A copper(II)/HOBt-catalyzed procedure for the synthesis of dipeptides and "general" amides has been developed using microwave irradiation to considerably hasten the reaction. As an alternative of using traditional carboxylic acids activation, the method relies on the use of N-acyl imidazoles as activated amino partners. By doing so, a nonconventional way to reach dipeptides and amides has been proposed through the challenging and less studied N → C direction synthesis. A series of dipeptides and "general" amides has been successfully synthesized and the applicability of the method has been illustrated in gram-scale syntheses. The mild reaction conditions proposed are completely adequate for couplings in the presence of sensitive amino acids, affording the products without detectable racemization. Furthermore, experimental observations prompted us to propose a plausible reaction pathway for the couplings.