Synthesis of 2, 5-Diamino-p-benzoquinones via Aerobic Oxidative C(sp2)-C(sp2) Bond Cleavage and Mechanistic Studies
Anandavally Asha, Jaice Ravindran, Subhadra Suma, Cherumuttathu H. Suresh,* and Ravi S. Lankalapalli*
A facile synthesis of 2, 5-diamino-p-benzoquinones (DABQs) is reported under very mild conditions by mere crystallization. Mechanistic studies by density functional theoretical (DFT) calculations revealed an oxidative C(sp2)-C(sp2) bond cleavage reaction mechanism via a dioxetane intermediate, from enamine oxidation of a mixture of ethyl vanillin and primary amines by triplet molecular oxygen. A second air oxidation event in the sequence of the reaction that results in C(sp2)-C(sp2) bond formation is also described by DFT studies. The mechanistic insights enabled synthesis of both symmetric and unsymmetric DABQs from primary amines with a broad substrate scope.
Chemistry Select 2020, 5, 2545-2550. DOI: 10.1002/slct.201904948.