Benzylic C-H functionalisation by [Et3SiH + KOtBu] leads to radical rearrangements in o-tolylaryl ethers, amines

Arokianathar, Jude N. and Kolodziejczak, Krystian and Bugden, Frances E. and Clark, Kenneth F. and Tuttle, Tell and Murphy, John A. (2020) Benzylic C-H functionalisation by [Et3SiH + KOtBu] leads to radical rearrangements in o-tolylaryl ethers, amines. Advanced Synthesis and Catalysis, 362 (11). pp. 2260-2267. ISSN 1615-4150

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    Abstract

    Reaction of Et 3SiH+KO tBu with diaryl ethers, sulfides and amines that feature an ortho alkyl group leads to rearrangement products. The rearrangements arise from formation of benzyl radicals, likely formed through hydrogen atom abstraction by triethylsilyl radicals. The rearrangements involve cyclisation of the benzyl radical onto the partner arene, which, from computation, is the rate determining step. In the case of diaryl ethers, Truce-Smiles rearrangements arise from radical cyclisations to form 5-membered rings, but for diarylamines, cyclisations to form dihydroacridines are observed. (Figure presented.).