Substrate-promoted ligand-free ruthenium-catalyzed conversion of levulinic acid to γ-valerolactone

Homogeneous selective hydrogenation often relies on sophisticated yet fragile ligands to improve catalytic performance. This not only complicates the process but also increases costs, thereby severely impeding its industrial application. In this work, we report a novel ligand-free strategy for the homogeneous conversion of levulinic acid using Ru 3 (CO) 12 , which proceeds via a substrate-promoted pathway. Under mild reaction conditions, excellent turnover numbers (up to 99000) and turnover frequencies (up to 2750 h  −1 ) were achieved for the production of γ-valerolactone. Mechanistic insights reveal that a levulinic acid-derived Ru 2 (CO) 4 sawhorse-type unit was formed in situ, and a catalytic cycle is proposed based on this key intermediate, outlining a new paradigm for practical and sustainable catalysis.