Copper-Catalyzed Direct Deaminative Borylation of Anilines – A Retro-Chan–Evans–Lam Reaction

Abstract

Arylboronic esters are indispensable intermediates in synthesis. We report a direct deaminative borylation of anilines enabled by anomeric amide activation with copper catalysis. The transformation proceeds via in situ generation of aryl radicals from isodiazene intermediates, followed by interception with a Cu–Bpin species derived from bis(pinacolato)diboron. Key to the success of this process is the use of an N-fluorosulfonamide oxidant, which promotes copper catalyst turnover and generates an electrophilic radical competent for polarity-matched hydrogen-atom transfer with the isodiazene intermediate. The method operates under mild conditions, tolerates electron-neutral and electron-rich anilines, and is applicable to pharmaceutically relevant substrates. The resulting aryl boronates can be further elaborated through oxidation or Suzuki–Miyaura cross-coupling, enabling modular C–C bond formation from simple aniline precursors.