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

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.)

Lithiation‐functionalisation of triazoles bearing electron‐withdrawing N‐substituents : challenges and solutions

The regioselective lithiation of 1,2,3-triazoles provides an opportunity to introduce additional functionality, however this simple functionalisation strategy using triazoles bearing electron-withdrawing N-substituents has not been investigated until now. Herein, we demonstrate that the lithiated triazole intermediates can readily decompose, even at −78 °C. In addition, lithiation-deuteration studies reveal lithiation can take place competitively on both the triazole and the electron-withdrawn aryl ring. Careful control of reaction conditions is therefore required to i) minimise decomposition pathways; and ii) facilitate regioselective functionalisation of the triazole

Make - underpinning concepts of the synthesis of systems where non-covalent interactions are important: general discussion

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