Aryl-Aryl Coupling Reaction Catalyzed by a Palladium Reagent Prepared from Pd(OAc)2 and n-Bu3P

A palladium reagent prepared from Pd (OAc) 2 (0.2 eq) and n-Bu 3 P (0.6 eq) catalyzed an aryl-aryl coupling reaction.This procedure is effective for coupling reactions of aryl triflate possessing no oxygen groups with arene, and of aryl iodide with arene.In our studies of the synthesis of fully aromatized benzo[c]phenanthridine alkaloids, we found that a novel Pd reagent prepared from Pd(OAc) 2 , a bidentate ligand DPPP, and n-Bu 3 P was very versatile for coupling reactions between aromatic triflate and arene. 1 We synthesized several benzo[c]phenanthridine alkaloids, using this novel method for intramolecular biaryl coupling reactions, not only between aryl triflates and arenes, but also between aryl halides and arenes. 2 However, a stoichiometric amount of palladium reagent was usually required to obtain a coupling product between an aromatic triflate and arene in a high and satisfactory yield, although the cyclization reaction proceeded even in the presence of 0.3 eq of Pd(OAc) 2 if