An Aerobic and Very Fast Pd/C-Catalyzed Ligand-Free and Aqueous Suzuki Reaction Under Mild Conditions

An aerobic, ligand-free Suzuki reaction catalyzed by Pd/C in aqueous media has been developed. This method is a very simple, efficient and mild protocol for the cross-coupling of aryl bromides with arylboronic acids, and the reactions proceeded smoothly in excellent yields within short reaction times. Control experiments demonstrated that the Pd/C-catalyzed Suzuki reaction was much quicker when performed in air or oxygen than in nitrogen. Furthermore, this protocol could be used for the synthesis of fluorinated liquid-crystalline compounds. The Pd/C catalyst could be recovered and recycled efficiently at least ten times without significant loss of catalytic activity.