Direct Construction of Quinoxaline Derivatives from Vicinal Diols and o‐Nitroanilines via NaOH‐Mediated Intermolecular Cascade Redox and Annulation Reactions

An alkali base, such as NaOH, alone can effectively mediate the intermolecular cascade redox and annulation reactions of o‐nitroanilines with vicinal diols, providing an efficient transition metal‐free method for direct construction of the useful quinoxaline derivatives. This method tolerates a wide range of substrates, can be readily performed in open air and scaled up for gram synthesis of several pharmaceutically and biologically active quinoxaline derivatives. Studies revealed that the nitro group works as the internal oxidant and the diols the reductant. Possible reaction paths were also proposed based on control reactions. For simple operation of the reactions, requiring no external reducing and oxidizing reagents, no inert atmosphere protection and no transition metal catalysts/ligands but only a water‐soluble alkali base, and having no transition metal residue contaminant in the products, this method may be a relatively greener and practical way for construction of the quinoxaline skeleton, especially for the pharmacy‐ or biology‐oriented quinoxaline derivatives. NaOH alone can mediate the annulation of o‐nitroanilines and vicinal diols in open air for quinoxaline skeleton construction. This method has a wide substrate scope, can be scaled up for gram synthesis of pharmaceutically‐active quinoxaline derivatives, and has advantages of simple operation, requiring no external reducing and oxidizing reagents, and having no transition metal residue contaminant in the products.