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.Key words: biphenyls, aryl–aryl coupling, multistep reactions, palladium, palladacycles, C-H activation, catalysis.