COOPERATIVE CATALYST EFFECTS IN PALLADIUM-MEDIATED CYANATION REACTIONS OF ARYL HALIDES AND TRIFLATES

Substoichiometric quantities of copper or zinc species dramatically im prove both conversion rate and efficiency of Pd(0)-catalyzed cyanation reactions. The optimum reaction conditions involve the use of a nitri le solvent, NaCN, and a catalyst system employing the combination of c uprous iodide with tetrakis(triphenylphosphine)palladium(0) [Pd(PPh3)( 4)]. Beneficial effects were observed for the conversion of aryl halid es, aryl triflates, and a vinyl bromide to the corresponding nitriles. The process was demonstrated on preparative scale with a broad range of aromatic and heteroaromatic substrates containing diverse functiona lity. A dual catalytic cycle is proposed to explain the profound influ ences of the cocatalyst system.