Application of N,N-Dimethylethanolamine as a One-Carbon Synthon for the Synthesis of Pyrrolo[1,2-a]quinoxalines, Quinazolin-4-ones, and Benzo[4,5]imidazoquinazolines via [5 + 1] Annulation

The synthesis of N-heterocycles composes a significant part of synthetic chemistry. In this report, a Cu(II)-catalyzed green and efficient synthesis of pyrrolo[1,2-a]quinoxaline, quinazolin-4-one, and benzo[4,5]imidazoquinazoline derivatives was developed, employing N,N-dimethylethanolamine (DMEA) as a C1 synthon. Green oxidant O2 is critical in these transformations, facilitating the formation of a key intermediate─a reactive iminium ion. The method conducted under mild conditions is compatible with a diversity of functional groups, providing an appealing alternative to the previously developed protocols.