Organic Superbase-Functionalized Fiber Catalyst for Green Catalysis of C–C Bond Formation and Downstream Tandem Reaction

A high-performance basic fiber catalyst (PANTBDF) was developed by loading 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) onto a polyacrylonitrile fiber. The functionalized fibers were thoroughly characterized using Fourier transform infrared spectroscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy. The characterization results confirmed that the physical and chemical properties of the fibers aligned with the design objectives at each modification stage, verifying the successful incorporation of the desired functional groups. To evaluate the catalytic performance of the synthesized fibers, the Knoevenagel reaction was employed as a model reaction. The results revealed that PANTBDF efficiently catalyzed the Knoevenagel condensation between various aromatic aldehydes and cyano-containing compounds under mild conditions (50 °C, 3 mol % catalyst loading, deionized water as solvent) within 2 h. A total of 31 products were obtained, with isolated yields ranging from 59% to 98%. Additionally, PANTBDF demonstrated remarkable catalytic activity in the Knoevenagel–Michael multicomponent tandem reaction, producing 27 substrates with isolated yields between 53 and 94%. Remarkably, PANTBDF demonstrated exceptional recyclability by maintaining nearly consistent reaction times and yields across 12 consecutive cycles, underscoring its robust performance and practical applicability. Finally, a plausible mechanism for the heterogeneous catalytic process was proposed, providing insight into the reaction pathway.