Distinct Promotive Effects of 1,8‐Diazabicyclo[5.4.0]undec‐7‐ene (DBU) on Polymer Supports in Copper‐Catalyzed Hydrogenation of C=O Bonds

An amidine base‐containing polymer, polystyrene‐bound 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (PS‐DBU), proved to serve as a prominent catalyst support. The combined use of selected copper salts with PS‐DBU in the catalytic hydrogenation of acetophenone qualifies DBU as beneficial to generate catalytically active species and stabilize them on the polymer. Catalyst preparation and characterization reveal that the active copper species is in a low‐valent state and the nanosized particles possibly grow on the amidine structure. The high immobilization ability of PS‐DBU almost entirely prohibited copper leaching to the product over six cycles of hydrogenation and catalyst recovery. The copper catalyst attached to PS‐DBU specifically promotes the hydrogenation of various ketones and aldehydes under 10 atm of H2 at 90 °C to afford alcoholic products in satisfactory yields. DBU‐modified polystyrene as an immobilization support for Cu: Hydrogenation of carbonyl compounds with a Cu catalyst immobilized on polystyrene‐bound 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (PS‐DBU) is reported. The PS‐DBU provides a suitable environment for formation and stabilization of catalytically active Cu species. The prepared Cu/PS‐DBU demonstrates high catalytic activity with negligible Cu leaching, robustness for recycle use, and broad functionality tolerance.