Efficient Production of Valuable Aromatic N-Heterocycles from Bio-Polyols by Heterogeneous Catalysis via Controlling Unstable Intermediate Conversion

One-step efficient production of high-valuebiobased aromatic N-heterocycles from polyols viain situ controllable utilizationof reactive pyruvaldehyde by heterogeneous Pt/CeO2 wasdemonstrated. Efficientand controllable conversion of renewable polyols to valuable N-containing products by heterogeneous catalysis, especiallyunder relativley mild conditions (<200 degrees C), remains a significantchallenge. Here, we develop a method for one-step efficient productionof 2-methylquinoxalines (2-MQs), a type of high-value aromatic N-heterocycles, directly from polyols in the presence ofsupported Pt dehydrogenation catalyst through controllably in situtrapping reactive pyruvaldehyde (PA) intermediate by aryl-1,2-diamineat the temperature of only 140 degrees C. The presence of aryl-1,2-diaminenot only enabled the formation of 2-MQs, but also markedly enhancedthe polyols' carbon utilization to near-quantitative (>98C%)level. More importantly, organic solvent-enabled kinetics controlof competitive reactions associated with PA transformation, i.e.,the condensation with aryl-1,2-diamine to produce 2-MQs and the Cannizzaroreaction to form lactic acid, allowed to access the desired 2-MQsin a controllable manner with yields ranging from 12 C% to 81 C%.The application of this approach to attain diverse 2-MQs and analoguesof interest in pharmaceutical industry has been demonstrated.

Automated summary

Efficient and controllable conversion of renewable polyols to valuable N-containing products by heterogeneous catalysis, especially under relatively mild conditions, was demonstrated. The method involved trapping reactive pyruvaldehyde (PA) intermediate by aryl-1,2-diamine to produce high-value aromatic N-heterocycles.