Electroreductive Remote Benzylic C(sp³)–H Arylation of Aliphatic Ethers Using Cyanoarenes for the Synthesis of α-(Hetero)aryl Ethers

Abstract

An iodoarene-driven electroreductive remote C(sp3)–H arylation of unsymmetrical 1-(o-iodoaryl)alkyl ethers with cyanoarenes for the site selective synthesis of α-(hetero)aryl ethers is developed. With the introduction of cyanoarenes as both aryl sources and electron transfer mediators, this method includes an iodoarene-driven strategy to enable the regiocontrollable formation of two new bonds, one C(sp2)–H bond, and one C(sp2)–C(sp3) bond, in a single reaction step through the sequence of halogen atom transfer (XAT), hydrogen atom transfer (HAT), radical–radical coupling, and decyanation.

Electroreduction strategy: a sustainable tool for the generation of aryl radicals

“…51 a Encouraged by these achievements, Li et al described a novel electroreductive HAT strategy for the precise activation of remote C(sp 3 )–H bonds by aryl radicals generated from aryl halides, establishing a novel and environmentally sustainable route to remote C(sp 3 )–H aryl/heteroarylation (Scheme 22). 52 The reaction was conducted in a simply operated undivided cell equipped with zinc as the sacrificial anode and graphite rod as the cathode, and a series of C(sp 3 )–H aryl/heteroarylation products were synthesized in moderate to good yields. Note that besides aryl iodides, the aryl bromides/chlorides with high reduction potentials could also be used as aryl radical precursors to activate the molecular C(sp 3 )–H bonds, although the efficiency was lower.…”