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

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journal contribution
posted on 2023-06-12, 11:35 authored by Feng Yu, Feng-Shou Xiao
Efficient and controllable conversion of renewable polyols to valuable N-containing products by heterogeneous catalysis, especially under relativley mild conditions (<200 °C), remains a significant challenge. Here, we develop a method for one-step efficient production of 2-methylquinoxalines (2-MQs), a type of high-value aromatic N-heterocycles, directly from polyols in the presence of supported Pt dehydrogenation catalyst through controllably in situ trapping reactive pyruvaldehyde (PA) intermediate by aryl-1,2-diamine at the temperature of only 140 °C. The presence of aryl-1,2-diamine not only enabled the formation of 2-MQs, but also markedly enhanced the polyols’ carbon utilization to near-quantitative (>98 C%) level. More importantly, organic solvent-enabled kinetics control of competitive reactions associated with PA transformation, i.e., the condensation with aryl-1,2-diamine to produce 2-MQs and the Cannizzaro reaction to form lactic acid, allowed to access the desired 2-MQs in a controllable manner with yields ranging from 12 C% to 81 C%. The application of this approach to attain diverse 2-MQs and analogues of interest in pharmaceutical industry has been demonstrated.