Comparison of mesoporous silica and alumina supports for palladium-catalyzed carbon-carbon coupling reactions: unexpected high acceleration by supported cetyltrimethylammonium bromide

The coupling reaction of p-iodoanisole and phenylboronic acid occurs with h igh yields in aqueous medium in the presence of palladium complexes with wa ter-soluble phosphine ligands on different mesoporous inorganic supports. S ilica and alumina supports were similarly prepared and functionalized with sulfonate groups. The catalyst was immobilized by ion exchange. A novel app roach to the amphiphilization of the supports by cetyltrimethylammonium bro mide was applied to modify phase transfer steps favorably and to embed the catalyst in this bipolar surface layer. The reaction is accelerated and con versions with these embedded catalysts exceed those in homogeneous systems. (C) 2001 Elsevier Science B.V. All rights reserved.