Catalytic Hydrogenation of Lignin‐Derived Aromatics With Rhodium Oxide in Water

Catalytic arene hydrogenation offers a direct pathway to saturated carbocycles. It can also be exploited to upgrade lignin‐derived aromatics. We have found that one of the most easily available rhodium compounds, rhodium(III) oxide, (Rh 2 O 3 ), is a highly efficient heterogeneous catalyst for arene hydrogenation in aqueous conditions. A diverse array of arene substrates, including those derived from lignin, underwent smooth conversion into their corresponding saturated products under 5 bar of hydrogen in water. This hydrogenation protocol displayed good compatibility with functional groups and showed tuneable chemoselectivity for α , β ‐unsaturated aryl ketones. Given the easy commercial availability of Rh 2 O 3 , the method provides a convenient route for synthesising three‐dimensional alicyclic compounds from two‐dimensional aromatic precursors, including those readily accessible from lignin depolymerisation.