Ligandless palladium catalyzed reactions of arylboronic acids and sodium tetraphenylborate with aryl halides in aqueous media

Polyfunctional biaryls are prepared by a modified Suzuki cross-coupling reaction between arylboronic acids or sodium tetraphenylborate and aryl halides ArX, X= 1, Br, Cl in aqueous solvents or neat water using a phosphine-free palladium catalyst, and in the presence of bases (Na2CO3 or NaOH). All four phenyl groups of Ph4BNa participate in the reaction. The reaction of Ph4BNa with aryl halides proceeds in water with high catalytic efficiency (250,000 catalytic cycles). (C) 1997 Elsevier Science Ltd.