One‐Step Approach to 2,5‐Diformylfuran from Fructose by Proton‐ and Vanadium‐Containing Graphitic Carbon Nitride

5‐Hydroxymethylfurfural (HMF) was selectively synthesized from fructose by using protonated graphitic carbon nitride [g‐C 3 N 4 (H + )] as a solid acid. With g‐C 3 N 4 as the same precursor material, 2,5‐diformylfuran (DFF) was efficiently obtained from aerobic oxidation of HMF by using vanadium‐doped g‐C 3 N 4 (V–g‐C 3 N 4 ) as an environmentally benign heterogeneous catalyst with atmospheric pressure of molecular oxygen as the oxidant. In addition, a combination of g‐C 3 N 4 (H + ) and V–g‐C 3 N 4 successfully afforded the direct synthesis of DFF from fructose through g‐C 3 N 4 (H + )‐promoted fructose dehydration and V–g‐C 3 N 4 ‐catalyzed successively aerobic oxidation of HMF to DFF in a one‐pot and two‐step process. Moreover, a bifunctional catalyst made of protonated V–g‐C 3 N 4 [V–g‐C 3 N 4 (H + )] allowed one‐pot as well as one‐step direct transformation of fructose into DFF. Under optimized conditions, 80 % yield of HMF and 82 % yield of DFF were obtained from g‐C 3 N 4 (H + )‐promoted fructose dehydration and V–g‐C 3 N 4 ‐catalyzed HMF oxidation, respectively. Stepwise addition of g‐C 3 N 4 (H + ) and V–g‐C 3 N 4 in the one‐pot process improved the DFF yield up to 63 % from fructose. In contrast, V–g‐C 3 N 4 (H + )‐catalyzed direct one‐step transformation of fructose into DFF led to a DFF yield of 45 %. The research highlights a one‐step approach to DFF from fructose with functional g‐C 3 N 4 catalyst.