32593-01-4Relevant academic research and scientific papers
High Site Selectivity in Electrophilic Aromatic Substitutions: Mechanism of C-H Thianthrenation
Berger, Florian,Duan, Meng,Houk, K. N.,Juliá, Fabio,Lu, Chenxi,Mateos, Javier,Plutschack, Matthew B.,Ritter, Tobias,Shao, Qianzhen,Xue, Xiao-Song
supporting information, p. 16041 - 16054 (2021/10/12)
The introduction of thianthrene as a linchpin has proven to be a versatile strategy for the C-H functionalization of aromatic compounds, featuring a broad scope and fast diversification. The synthesis of aryl thianthrenium salts has displayed an unusually highpararegioselectivity, notably superior to those observed in halogenation or borylation reactions for various substrates. We report an experimental and computational study on the mechanism of aromatic C-H thianthrenation reactions, with an emphasis on the elucidation of the reactive species and the nature of the exquisite site selectivity. Mechanisms involving a direct attack of arene to the isolatedO-trifluoracetylthianthreneS-oxide (TT+-TFA) or to the thianthrene dication (TT2+) via electron transfer under acidic conditions are identified. A reversible interconversion of the different Wheland-type intermediates before a subsequent, irreversible deprotonation is proposed to be responsible for the exceptionalparaselectivity of the reaction.
