Improvements in cross coupling reactions of hypervalent siloxane derivatives

The scope of the palladium-catalyzed cross coupling reaction of aryl halide s with phenyltrimethoxysilane has been expanded to include aryl bromides, h eteroaryl bromides, and aryl chlorides; A more general Pd(0)-catalyst/ligan d system has been developed to activate bromides: palladium(ll) acetate (Pd (OAc)(2)) is activated with triphenylphosphine (PPh3) or tri-o-tolylphosphi ne (P(o-tol)(3)) (1:2 molar ratio of Pd:phosphine). Coupling of aryl chlori de derivatives required addition of 2-(dicyclohexylphosphino)biphenyl (Buch wald's ligand) to Pd(2)dba(3) (tris(dibenzylideneacetone)dipalladium(0)) (1 :1.5 molar ratio of Pd:phosphine).