Protecting-group-free ortho-C–H borylation of anilines enabled by mesoionic carbene-Ir complex

Abstract

We describe an iridium-catalyzed ortho-selective C–H borylation of unprotected anilines. The employing strong σ-donating cyclometalated mesoionic carbene as C^C bidentate ligand is crucial for the high ortho-selectivity. Computational studies support outer-sphere X–H···Oboryl hydrogen bond interactions, which are strengthened by bidentate C^C ligand introduction. The method shows broad substrate scope and high functional group tolerance.

Keywords

• Protecting-group-free
• C–H borylation
• Hydrogen bonding
• Regioselectivity
• Mesoionic carbene