Para‐Selective C−H Borylation of Aromatic Quaternary Ammonium and Phosphonium Salts

Abstract

AbstractAromatic ammonium and phosphonium salts are important synthetic intermediates and multifunctional materials, but para‐selective functionalization of the aromatic salts remains a challenge. Here we develop an ionic ligand based on our newly designed “biphenyl‐phenanthroline” skeleton and realize the Ir‐catalyzed para‐selective C−H borylation of seven types of aromatic quaternary ammonium and phosphonium salts. Gram‐scale transformation, late‐stage elaboration for drug molecule, and diversification of borylated products demonstrate the potential utility of this reaction. The mechanistic studies and computational analysis elucidate the origin of para‐selectivity.