Reusable and Ligand‐Free Palladium‐Catalyzed Suzuki‐Miyaura Cross‐Couplings of Aryl Halides with Arylboronic Acids in Tetra ‐n‐ butylammonium Bromide

Ligand‐free and reusable palladium‐catalyzed Suzuki‐Miyaura cross‐coupling reaction performed in TBAB (tetra‐ n ‐butylammonium bromide) was presented. It was found that the amount of water affected these reactions. Excellent results were obtained when there was w =1% of water in TBAB. In the presence of 3 mol% of Pd(OAc) 2 and 1.5 g of TBAB (containing w =1% of water), a number of aryl halides were coupled with arylboronic acids smoothly in moderate to excellent yields. Moreover, the Pd(OAc) 2 /TBAB system among the couplings of aryl bromides and activated chlorides could be recovered and reused three times without a loss of catalytic efficiency.