Methylated Arene Products Establish Ground State Electron Transfer from KOtBu in the Reductive Activation of Aryl Halides

In the presence of appropriate aryl halides, electron transfer occurs from KOtBu to form tert-butoxyl radicals that can fragment into methyl radicals. In support of electron transfer, we report the first observation of methylated arene products, arising from attack by these methyl radicals. When KOtBu is replaced by KOC(Et)3, ethyl radicals are correspondingly trapped. The conversion of KOtBu to methyl radicals happens in the presence of haloarene substrates. The reactions are not light-dependent. We illustrate the scope of the KOtBu-promoted aryl radical formation with a range of substrates that includes haloanthracenes, dihaloanthracenes, a dihalonaphthalene, and a dihalobenzene.