N-arylation of benzimidazole with arylboronate, boroxine and boronic acids.: Acceleration with an optimal amount of water

The coupling of benzimidazole 1 with arylboronate, boroxine, and boronic acids is accelerated efficiently by the addition of an optimal amount of water. This coupling reaction proceeds in nearly quantitative yield at 30degreesC under an atmosphere of air within 24 hours. Under these conditions, the reaction tolerates both electron-donating and electron-withdrawing substituents at the ortho-, meta, or para-positions of the phenylboronic acid.