Selective Monoarylation of Dibromoarenes with Polymeric Palladium Catalyst
Y. Uozumi*, M. Kikuchi
Institute for Molecular Science, Okazaki, Japan
21 September 2005 (online)
A selective monoarylation of dibromoarenes with arylboronic acids was successfully achieved in water by use of a polystyrene-poly(ethylene glycol) (PS-PEG) resin-supported palladium catalyst. The cross-coupling reaction of o-, m- and p-dibromoarenes 2 with electron-rich and electron-deficient arylboronic acids (1.0 equiv) took place in the presence of catalyst 1 (1-2 mol%) and triphenylphosphine in aqueous potassium carbonate and toluene [1% (v/v)] to give bromobiaryls 3 with high selectivity (14 combinations, 75-95% yields, 3:4 = 81:19 ³ 99:<1). The catalyst 1 was readily recovered by filtration and reused without significant loss of catalytic activity and selectivity (89-94% yields, 3:4 = 98:2-99:1 for three times). Unsymmetrically substituted teraryls 5 were synthesized in one pot by sequential arylation of dibromoarenes with two kinds of arylboronic acids.