Corn Stover-Derived Lewis Acid Carbon Catalyst for Efficient Hantzsch Synthesis of 1,4-Dihydropyridines

The development of sustainable heterogeneous catalysts from renewable biomass is an important strategy for advancing green organic synthesis. In this work, a series of Lewis acid carbon catalysts were prepared from corn stover via AlCl₃-assisted activation and thermal carbonization. The optimized catalyst, CS-AlCl₃ (1:1-500), exhibited a predominantly mesoporous structure with accessible aluminum-derived Lewis acid sites, as confirmed by BET, FT-IR, XRD, XPS, TEM, NH₃-TPD, and pyridine-FTIR analyses. Under optimized conditions, the catalyst efficiently promoted the Hantzsch multicomponent reaction, affording up to 97% isolated yield within 30 min in ethanol at 105 °C. The catalyst exhibited broad substrate scope (90.95-97.35% yields) and retained good catalytic activity over five consecutive reuse cycles. Pyridine poisoning, hot filtration, postreaction ICP-OES, BET, and XPS analyses confirmed that the reaction proceeds predominantly through a heterogeneous mechanism and that the superior catalytic performance originates from the synergistic interplay between a stable mesoporous carbon framework and accessible aluminum-derived Lewis acid sites. Compared with recently reported heterogeneous catalysts, CS-AlCl₃ (1:1-500) provides competitive catalytic efficiency together with the advantages of renewable biomass utilization, simple preparation, and catalyst recyclability. This work establishes a validated structure-acidity-activity relationship for biomass-derived Lewis acid carbon catalysts and demonstrates their potential for sustainable multicomponent synthesis.