Electrochemical oxidation-induced etherification via C(sp<sup>3</sup>)─H/O─H cross-coupling.

Wang, Huamin; Liang, Kailun; Xiong, Wenpeng; Samanta, Supravat; Li, Wuqin; Lei, Aiwen · Sci Adv · 2020

basic_science · Level V

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Abstract

Direct electrochemical construction of C─O bonds through C(sp<sup>3</sup>)─H functionalization still remains fundamentally challenging. Here, electrochemical oxidation-induced benzylic and allylic C(sp<sup>3</sup>)─H etherification has been developed. This protocol not only offers a practical strategy for the construction of C─O bonds using nonsolvent amounts of alcohols but also allows direct electrochemical benzylic and allylic C(sp<sup>3</sup>)─H functionalization in the absence of transition metal catalysis. A series of alcohols and benzylic and allylic C(sp<sup>3</sup>)─H compounds were compatible with this transformation. Mechanistically, the generation of aryl radical cation intermediates is the key to this C(sp<sup>3</sup>)─H etherification, as evidenced by radical probe substrate (cyclopropane ring opening) and electron paramagnetic resonance experiments.