Characterization of -Amino Ester Enolates as Hexamers via 6Li NMR Spectroscopy

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• 作者：Anne J. McNeil ; Gilman E. S. Toombes ; Sithamalli V. Chandramouli ; Benoit J. Vanasse ; Timothy A. Ayers ; Michael K. O'Brien ; Emil Lobkovsky ; Sol M. Gruner ; John A. Marohn ; and David B. Collum
• 刊名：Journal of the American Chemical Society
• 出版年：2004
• 出版时间：May 19, 2004
• 年：2004
• 卷：126
• 期：19
• 页码：5938 - 5939
• 全文大小：101K
• 年卷期：v.126,no.19(May 19, 2004)
• ISSN：1520-5126

文摘

Low-temperature ⁶Li NMR spectroscopic studies on a chiral -amino ester enolate reveal a complex mixture of homo- and heterochiral aggregates. Subsequent warming of the samples led to rapid intra-aggregate exchange, resulting in four distinct resonances consistent with an ensemble of hexamers. An implicit fit of the aggregate populations to the Boltzmann distribution provided the free energy differences and equilibrium constants. An X-ray crystal structure obtained from the racemic enolate is consistent with the predominant aggregate in solution.