Remote Selective C−H Halogenation of Arylphosphine Oxides with Ferric Halides

We developed the remote selective C−H bromination for the synthesis of C4′‐brominated biarylphosphine oxides using FeBr 3 as a brominating reagent. C3′‐Brominated products were obtained in reactions with substrates bearing a 2,4,6‐triisopropyl substituent on the bottom ring. Moreover, direct access to C5‐chlorinated peri ‐substituted(1‐naphthalenyl)phosphines is developed using FeCl 3 as a chlorinating reagent. These halogenated compounds can be utilized for cross‐coupling reactions to construct functionalized phosphine oxides.