Reactivity of the Triple Ion and Separated Ion Pair of Tris(trimethylsilyl)methyllithium with Aldehydes: A RINMR Study

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• 作者：Amanda C. Jones ; Aaron W. Sanders ; William H. Sikorski ; Kristin L. Jansen ; Hans J. Reich
• 刊名：Journal of the American Chemical Society
• 出版年：2008
• 出版时间：May 14, 2008
• 年：2008
• 卷：130
• 期：19
• 页码：6060 - 6061
• 全文大小：650K
• 年卷期：v.130,no.19(May 14, 2008)
• ISSN：1520-5126

文摘

Low-temperature rapid-injection NMR (RINMR) experiments were performed on tris(trimethylsilyl)methyllithium. In THF/Me₂O solutions, the separated ion (1S) reacted faster than can be measured at −130 °C with MeI and substituted benzaldehydes (k ≥ 2 s⁻¹), whereas the contact ion (1C) dissociated to 1S before reacting. Unexpectedly, the triple ion reacted faster with electron-rich benzaldehydes relative to electron-deficient ones. The addition of HMPA had no effect on the rate of reaction of the triple ion with p-diethylaminobenzaldehyde, and the immediate product of the reaction was the HMPA-solvated separated ion 1S, with the Peterson product forming only slowly. Thus, the aldehyde is catalyzing the dissociation of the triple ion. HMPA greatly decelerated the reaction of 1S (<10⁻¹⁰), providing an estimate of the Lewis acid activating effect of a THF-solvated lithium cation in an organolithium addition to an aldehyde.