Large acceleration of solvent-free Suzuki-Miyaura cross-coupling reactions at room temperature by the addition of small amounts of dioxane and water

The addition of small amounts of dioxane and water was quite useful in solvent-free Suzuki-Miyaura cross-coupling reactions. Various solid and liquid aryl bromides and chlorides reacted with boronic acids in the presence of 1 mol% of Pd(OAc)2 and 2 mol% of RuPhos at 25 °C to give the corresponding biaryls in good to excellent yields. The reactions of aryl chlorides proceeded faster than those of the corresponding bromides. 0.2 mol% of Pd(OAc)2 was sufficient for the reactions of some aryl chlorides. This procedure is especially useful for the reactions of aryl chlorides.