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

Abstract

The synthesis of <i>N</i>-heterocycles composes a significant part of synthetic chemistry. In this report, a Cu(II)-catalyzed green and efficient synthesis of pyrrolo[1,2-<i>a</i>]quinoxaline, quinazolin-4-one, and benzo[4,5]imidazoquinazoline derivatives was developed, employing <i>N,N</i>-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.