Ni(II) catalyzed bromination of aryl C–H bonds

• Report of an air-stable Ni(II) catalyst for C–H functionalizaton.
• C–C homocoupling was avoided by Ni(II).
• Catalytic conditions under which Ni(II) salts can catalyze C–H bromination.
• C–H halogenation happens at room temperature.
• N-bromosuccinimide (NBS), instead of hazardous Br2, is the bromine-source.

Bromination of unactivated aromatic C–H bonds without directing and/or chelating groups was achieved by employing an air stable N-heterocyclic Ni(II) complex. PhI(OAC)2 and N-bromosuccinimide have been used as the oxidizing agent and the bromine source, respectively. Yields for bromination are as high as >99%, especially in presence of electron-withdrawing groups like –NO2 and –CF3. This is a rare report on C–H bond activation with Ni(II) where, instead of homo C–C coupling, reductive elimination to form C-halogen could be achieved.

Ni(II) of distorted square planar geometry allows C–H halogenation avoiding C–C homocoupling.Figure optionsDownload as PowerPoint slide