Environmentally friendly synthesis of biaryls: Suzuki reaction of aryl bromides in water at low catalyst loadings

Pd(DPPF)Cl2 is shown to be an extremely active catalyst for the Suzuki reaction of aryl bromides in water. This green procedure provides biaryls in excellent yields and high turnover numbers (TONs) (TONs up to 870,000 for the reaction of 1-bromo-4-nitrobenzene and phenylboronic acid). A small amount of PEG-2000 also allows the recycling of the palladium catalyst for three times without any significant loss of catalytic activity.