Cobalt disulfide promotes the selective rearrangement–hydrodeoxygenation of furan alcohols to cyclopentenones

Developing an efficient catalyst for converting furan alcohols to cyclopentenones for fine chemical synthesis is crucial but challenging due to the easy overhydrogenation side reactions to tetrahydrofuran alcohols and cyclopentanones. This study demonstrates that cobalt disulfide (CoS₂) exhibits an unprecedented yield of 80.1% during rearrangement–hydrodeoxygenation of furan alcohol to cyclopentenone. CoS₂ acts not only as the Lewis acid sites for the rearrangement step but also as adjustable H₂ activation sites for the CC hydrogenation of 4-hydroxy-2-cyclopentenone intermediates, promoting the efficient synthesis of cyclopentenone. Furthermore, it exhibits, for the first time, a similar synthesis route toward 3-methyl cyclopentenone from 5-methyl furan alcohol and 2,5-dihydroxymethyl furan. In addition, we further explored the high-value utilization of cyclopentenones to high-density fuels with densities of 0.904–0.908 g/mL via self-photosensitized [2 + 2] cycloaddition and subsequent hydrodeoxygenation. This study presents the green and efficient synthesis of two cyclopentenones and a way for their high-value utilization as high-density fuels.