Palladium-Catalyzed Arylation of α,α-Disubstituted Arylmethanols via Cleavage of a C−C or a C−H Bond To Give Biaryls

The palladium-catalyzed arylation of α,α-disubstituted arylmethanols with aryl halides proceeds
not only via C−H bond cleavage at the ortho-position, but also via cleavage of the sp2−sp3 C−C
bond with the liberation of ketones (β-carbon elimination) to give the corresponding biaryls. Both
reactions appear to occur through common arylpalladium(II) alcoholate intermediates. The results
of systematic studies with respect to which C−C or C−H bond is preferentially cleaved in the
arylation are reported. Among the important findings is the selective elimination of ortho-substituted
aryl groups even from aryl(diphenyl)methanols due to steric reasons. Thus, various biaryls having
ortho-substituents can be produced efficiently by treatment of the corresponding aryl(diphenyl or
dimethyl)methanols with aryl bromides and chlorides.