meta-C–H functionalization of phenylethyl and benzylic alcohol derivatives via Pd/NBE relay catalysis

Abstract

The transition metal-catalyzed meta-C–H functionalization of alcohols and their hydroxylamine derivatives remains underdeveloped. Herein, we report an efficient meta-C–H arylation of both phenylethyl and benzylic alcohols and their hydroxylamine derivatives using a readily removable oxime ether directing group. Using electronically activated 2-carbomethoxynorbornene as the transient mediator and 3-trifluoromethyl-2-pyridone as the enabling ligand, this reaction features a broad substrate scope and good functional group tolerance. More importantly, with this oxime-directed meta-C–H functionalization, this method provides a dual approach for efficient access to both meta-substituted alcohols and hydroxylamines using two sets of simple deprotection conditions. This protocol leads to the efficient synthesis of bioactive compounds possessing promising reactivities for the treatment of pulmonary fibrosis.