Palladium-catalysed synthesis of nonsymmetrically disubstituted-1,1′-biphenyls from o-substituted aryl iodides through aryl coupling and delayed hydrogenolysis

In the presence of Pd(OAc)(2) and norbornene as catalysts, two molecules of an ortho-substituted aryl iodide undergo aryl-aryl coupling to a palladium-bonded biphenylyl intermediate, which is hydrogenolyzed by benzyl alcohol to give 2,3'-disubstituted biaryl derivatives in satisfactory yields. A curious behaviour was observed with o-chloroiodobenzene, which gave activation of the C-Cl bond with four-membered ring formation.