Et3N-catalyzed oxidative dehydrogenative coupling of α-unsubstituted aldehydes and ketones with aryl diamines leading to quinoxalines using molecular oxygen as oxidant

A novel Et3N-catalyzed oxidative dehydrogenative coupling of alpha-unsubstituted carbonyl compounds with aryl diamines leading to quinoxaline derivatives using molecular oxygen as oxidant has been developed. Six hydrogen dissociations involving 2 sp(3) C-H bonds activation are realized under mild conditions in this approach. Plausible mechanism is proposed for this novel Et3N-catalyzed transformation on the basis of the aboratively designed mechanistic studies including the radical detection by EPR. (C) 2012 Elsevier Science. All rights reserved. (C) 2012 Elsevier Ltd. All rights reserved.