Microwave Assisted Lewis Acid Catalysis for Green Synthesis of Sustainable Nitrogen Heterocycles from Biomass-Derived Alcohols

Biobased alcohols derived from lignocellulose have attracted widespread attention in the field of high-value utilization due to their structural diversity, renewability, and excellent conversion potential. However, directly utilizing these alcohol compounds to efficiently construct molecular frameworks still faces challenges, such as poor selectivity and high energy consumption. In this study, we propose a microwave-assisted Lewis acid (FeCl3) cocatalysis strategy to achieve the efficient conversion of various biomass-derived alcohols, such as lactic acid, lactic acid esters, primary alcohols, secondary alcohols, diols, and natural product alcohols, into biobased nitrogen heterocycles (quinolines and pyridines). This method enhances the tandem dehydration and dehydrogenation process of biomass alcohols through the rapid and uniform heating of microwaves and the synergistic activation of substrates by an FeCl3 Lewis acid, thereby significantly improving conversion efficiency and product selectivity. Moreover, the strategy successfully realized the one-pot synthesis of the drug molecule Cinchophen from biomass-derived raw materials, demonstrating good application potential. Compared to traditional methods, this approach is not only applicable to various structural types of biomass-derived alcohols but also achieves selective activation and conversion of the O–H bond, reflecting a higher level of reaction control and green advantages in sustainable conversion.