Synthesis of o-(diphenylphosphinoyloxy)anilines by the rhodium-catalyzed reaction of nitroarenes and diphenylphosphine oxide

A rhodium complex Rh 2 (OAc) 4 catalyzed the reaction of nitrobenzenes and diphenylphosphine oxide HP( O)Ph 2 giving o -(diphenylphosphinoyloxy)anilines predominantly, which were accompanied by small amounts of the p -isomers. Nitorobenzenes possessing a bulky o -substituent, particularly o -( t -butyl)nitrobenzenes, underwent the reaction in high yields. The reaction is considered to involve the reductive formation of O -phosphinoyl- N -arylhydroxyamines from nitrobenzenes, and o -phosphinoyloxylation by the rearrangement.