Direct 2,2,2-Trifluoro and 2,2-Difluoroethoxylation of a Model Macrocyclic Ar−H Substrate via Ni-Catalysis

Abstract

Herein, we describe the trifluoro- and difluoroethoxylation of C(sp²)-H bonds using nickel(II) complexes incorporating a model macrocyclic arene substrate. Due to the coordinative properties of the macrocyclic substrate, we were able to detect and characterize the just-formed C(sp²)−OCH₂CF₃−Ni(II) species by HRMS and IRPD. DFT studies on the C(sp²)−OCH₂CF₃ bond formation mechanism indicate that it involves a Ni(III)/Ni(I) reductive elimination followed by oxidation to Ni(II) rather than the higher energy barrier Ni(IV)/Ni(II) reductive elimination. This mechanistic investigation deepens the versatile redox abilities of Ni compounds and might help in designing new catalysts for the 2,2,2-trifluoroethoxylation and 2,2-difluoroethoxylation of arene C−H bonds.