Construction of Biaryls from Aryl Sulfoxides and Anilines by Means of a Sigmatropic Rearrangement.

An unprecedented S-N variant of the benzidine rearrangement for construction of biaryls has been developed. Aryl sulfoxides underwent dehydrogenative coupling with anilines by successive treatment with trifluoromethanesulfonic anhydride and trifluoromethanesulfonic acid to provide the corresponding 2-amino-2'-sulfanyl- and/or 4-amino-4'-sulfanylbiphenyls. Mechanistic studies indicate that the C-C-bond-forming sigmatropic rearrangement proceeds intramolecularly from dicationic S-N-tethered species.