Oxidative radical arylation of anilines with arylhydrazines and dioxygen from air.

Substituted 2-aminobiphenyls have been prepared from arylhydrazine hydrochlorides and anilines in biphasic radical arylation reactions with dioxygen from air as a most simple and readily available oxidant. Under optimized conditions, the free amino functionality of the aniline leads to high ortho:meta regioselectivities, now even for anilines bearing a donor substituent in the para position. Finally, the mild and metal-free new access to aminobiphenyls was shown to be applicable on a gram scale.