Aggregation studies of complexes containing a chiral lithium amide and n-butyllithium
Aggregation studies of complexes containing a chiral lithium amide and n-butyllithium
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DOI：
10.1021/jo702655m
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发表时间：
2008-03-21
影响因子：
3.6
通讯作者：
Williard, Paul G.
中科院分区：
文献类型：
--
作者：
Li, Deyu;Sun, Chengzao;Williard, Paul G.
使用 H-1 和 C-13 INEPT DOSy、Li-6 和 N-15 NMR 以及其他 2D NMR 技术研究了由手性氨基锂和正丁基锂在 tol-d(8) 溶液中组成的体系。当化学计量接近 1.5 当量的正丁基锂与 1 当量的胺化合物时，混合的 2:1 三聚复合物被确定为主要物质。 H-1 和 C-13 INEPT DOSY 光谱证实了溶液中存在这种锂聚集体。聚集体的分子式权重与内参的扩散系数相关，表明了该复合物的聚集数。 log D-rel 与 log FW 的图是线性的 (r > 0.9900)。 Li-6和N-15 NMR滴定实验也证实了这些结果。这些 NMR 实验表明，这种混合聚集体是导致正丁基锂不对称加成到醛上的物质。
A system consisting of a chiral lithium amide and n-BuLi in tol-d(8) solution was investigated with H-1 and C-13 INEPT DOSy, Li-6 and N-15 NMR, and other 2D NMR techniques. A mixed 2:1 trimeric complex was identified as the major species as the stoichiometry approached 1.5 equiv of n-BuLi to 1 equiv of amine compound. H-1 and C-13 INEPT DOSY spectra confirmed this lithium aggregate in the solution. The formula weight of the aggregate, correlated with diffusion coefficients of internal references, indicated the aggregation number of this complex. Plots of log D-rel vs log FW are linear (r > 0.9900). Li-6 and N-15 NMR titration experiments also corroborated these results. These NMR experiments indicate that this mixed aggregate is the species that is responsible for asymmetric addition of n-BuLi to aldehydes.