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 30 °C 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.