Sustainable production of value-added N-heterocycles from biomass-derived carbohydrates via spontaneous self-engineering

Synthetic N-heterocyclic compounds,such as quinoxalines,have shown a crucial role in pharmaceutical as well as food and dye industries.However,the traditional synthesis toward N-heterocycles relies on multistep energy and cost-intensive non-sustainable processes.Here,we report a facile approach that allows one-step conversion of biomass-derived carbohydrates to valuable quinoxalines in the presence of aryl-1,2-diamines in water without any harmful metal catalysts/organic solvents via spontaneously engineering involved cascade reactions under hydrothermal conditions.Aryl-1,2-diamines are revealed as the key to propel this transformation through boosting carbohydrate fragmentation into small 1,2-dicarbonyl intermediates and subsequently trapping them for constituting stable quinoxaline scaffolds therefore avoiding a myriad of undesired side reactions.The tunability of product selectivity can be also achievable by adjusting the basicity of the reaction environment.Both batch and continuous-flow integrated processes were verified for production of quinoxalines in an ex-ceptionally eco-benign manner(E-factor＜1),showing superior sustainability and economic viability.