posted on 2023-06-12, 11:35authored byFeng 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.