Iridium nitrenoid-enabled arene C−H functionalization

Abstract

Direct arene C−H functionalization via nucleophilic aromatic substitution remains a challenging task. Here we report an iridium nitrenoid-catalysed arene C−H functionalization strategy, making use of readily available aryl azides as electrophiles to react with different nucleophilic reaction partners. The practicality of this methodology is demonstrated by enantioselective synthesis of chiral 2-amino-2′-hydroxy-1,1′-binaphthyl, a class of building blocks, ligands and catalysts in asymmetric transformation, using β-naphthols and β-naphthyl azides as starting materials under the catalysis of a tailored oxazoline-chelated iridium complex. Mechanistic studies and density functional theory calculations show that the reaction proceeds through an iridium nitrenoid-mediated C−H functionalization pathway. The reported arene C−H functionalization strategy serves as a blueprint to expand the applicability of nucleophilic aromatic substitution reactions and is particularly valuable for the synthesis of aniline-containing molecules. Effective strategies for direct arene C−H functionalization are sought after. Here arene C−H functionalization via iridium nitrenoid-catalysed nucleophilic aromatic substitution allows the coupling of aryl azides with different carbon nucleophiles and is applied to the enantioselective synthesis of NOBINs