Liou Lara R, McNeil Anne J, Toombes Gilman E S, Collum David B
Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301, USA.
J Am Chem Soc. 2008 Dec 24;130(51):17334-41. doi: 10.1021/ja8016957.
The solution structures of four enolates derived from beta-amino esters are investigated using (6)Li NMR spectroscopy in conjunction with the method of continuous variation (method of Job). Ensembles of homo- and heteroaggregated enolates are generated by mixing enantiomers of a single enolate (R/S mixtures), opposite antipodes of two different enolates (R/S' mixtures), and the same antipodes of two different enolates (R/R' mixtures). The numbers of observable aggregates and their dependence on the mole fraction of the two enolates confirm the hexamer assignments. Inherent symmetries observable in the (6)Li NMR spectra show the stereochemistry of chelation about the hexagonal drum.
使用⁶Li核磁共振光谱法结合连续变化法（乔布法）研究了四种源自β-氨基酯的烯醇盐的溶液结构。通过混合单一烯醇盐的对映体（R/S混合物）、两种不同烯醇盐的相反对映体（R/S'混合物）以及两种不同烯醇盐的相同对映体（R/R'混合物）来生成均聚和杂聚烯醇盐的集合体。可观察到的聚集体数量及其对两种烯醇盐摩尔分数的依赖性证实了六聚体的归属。在⁶Li核磁共振光谱中可观察到的固有对称性显示了围绕六边形鼓的螯合立体化学。
