Water-soluble palladacycles as precursors to highly recyclable catalysts for the suzuki coupling of aryl bromides in aqueous solvents

A family of water-soluble palladacycles was prepared from benzylamine or benzaldehyde imine ligands bearing hydrophilic functional groups. The palladacycles derived from N,N-dimethyl-p-hydroxybenzylamine (7) and sodium 4-(N-benzylideneamino) benzenesulfonate (10) gave active catalysts for the Suzuki coupling of aryl bromides and activated aryl chlorides in combination with (2-di-tert-butylphosphinoethyl)trimethylammonium chloride (t-Bu-Amphos). The catalyst derived from 10/t-Bu-Amphos could be used for 12 reaction cycles in the Suzuki coupling of 4-bromotoluene at 80 degrees C before a significant loss of catalyst activity was observed.