Direct Transformation of HMF into 2,5‐Diformylfuran and 2,5‐Dihydroxymethylfuran without an External Oxidant or Reductant

Abstract The selective transformation of 5‐hydroxymethylfurfural (HMF) to valuable 2,5‐diformylfuran (DFF) and 2,5‐dihydroxymethylfuran (DHMF) is highly desirable but remains a great challenge owing to its tendency to over‐oxidation and over‐reduction. In this work, HMF is directly converted into DFF and DHMF without external oxidant or reductant through a Meerwein–Ponndorf–Verley–Oppenauer (MPVO) reaction. In such a MPVO process, HMF is used as both oxidant and reductant and DFF and DHMF are simultaneously produced with a 1:1 molar ratio in the presence of a Lewis acid catalyst. Under high initial HMF concentration, a HMF conversion of up to 44.7 % can be reached within 1 h. Moreover, this atom‐efficient transformation route for HMF also provides a promising protocol for the crude separation of DHMF products from DFF products, owing to the lower solubility of DHMF compared to DFF in acetonitrile.