Vanadium oxide-doped phosphazene-based covalent organic framework: a sustainable catalyst for 2,5-diformylfuran (DFF) and benzoazole synthesis

Abstract

The one-pot conversion of high-value bio-based chemicals from carbohydrates offers an economical and sustainable approach to utilizing renewable biomass resources. In this study, we have developed a V@COF-1 sustainable catalyst that provides efficient and excellent catalytic activity for the direct conversion of various carbohydrates into 2,5-diformylfuran (DFF) due to vanadium oxide supported by phosphazene polymeric framework active sites. Under the stepwise optimized reaction conditions, the formation of DFF was achieved using fructose and glucose in 92% and 87% isolated yield, respectively, in the presence of molecular oxygen in 8–12 hours. The reactivity of the catalyst was tested using various carbohydrates with good to moderate yield of DFF. The catalyst can be easily separated, regenerated, and reused six times, which signified its potential application toward the synthesis of DFF from carbohydrates. From this catalytic efficiency of V@COF-1 in the oxidation reaction, we have tested the catalytic activity for the synthesis of benzaldehyde and benzoazoles using benzyl alcohol under mild conditions. These reactions facilitate a wide substrate scope with a high yield and reuse of the catalyst without a remarkable decrease in its catalytic efficiency. To explore the application of these findings, this approach was applied to the direct conversion of xylose or ribose into furfural as an intermediate substrate, which condensed with 1,2-diaminobenzene to give fuberidazole fungicide in good yield.