Faculté des sciences

Synthesis and structure of m-terphenyl thio-, seleno-, and telluroethers

Zakai, Uzma I. ; Błoch-Mechkour, Anna ; Jacobsen, Neil E. ; Abrell, Leif ; Lin, Guangxin ; Nichol, Gary S. ; Bally, Thomas ; Glass, Richard S.

In: Journal of Organic Chemistry, 2011, vol. 75, no. 24, p. 8363–8371

Several routes for the synthesis of m-terphenyl thio-, seleno-, and telluroethers were investigated. m-Terphenyl iodides react with diphenyl diselenides or ditellurides (CsOH·H₂O, DMSO, 110 °C) to give the desired compounds in 19−84% yield which significantly extends the previously reported such reactions because o-benzyne cannot be an intermediate as previously... Plus

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    Summary
    Several routes for the synthesis of m-terphenyl thio-, seleno-, and telluroethers were investigated. m-Terphenyl iodides react with diphenyl diselenides or ditellurides (CsOH·H₂O, DMSO, 110 °C) to give the desired compounds in 19−84% yield which significantly extends the previously reported such reactions because o-benzyne cannot be an intermediate as previously suggested. However, the most general synthetic route was that involving reaction of 2,6-diaryl Grignard reagents with sulfur, selenium, or tellurium electrophiles. The m-terphenyl thio-, seleno-, and telluroethers were characterized spectroscopically and, in one case, by single-crystal X-ray analysis. Certain of these compounds showed atropisomerism and barriers for interconversion of isomers were determined by variable-temperature NMR spectroscopy. The barriers for interconverting the syn and anti atropisomers increase on going from the analogous S to Se to Te compounds. Calculations on this isomerization revealed that the barriers are due to rotation about the aryl−aryl bond and that the barriers for rotation about the aryl−chalcogen bond are much lower.