Department of Chemistry, Brown University , 324 Brook Street,Providence, Rhode Island 02912, United States.
J Am Chem Soc. 2013 Sep 25;135(38):14367-79. doi: 10.1021/ja406912h. Epub 2013 Sep 17.
The crystal structure of a mixed aggregate containing lithiated (S)-N-ethyl-3-methyl-1-(triisopropylsilyloxy)butan-2-amine derived from (S)-valinol and cyclopentyllithium is determined by X-ray diffraction. The mixed aggregate adopts a ladder structure in the solid state. The ladder-type mixed aggregate is also the major species in a toluene-d8 solution containing an approximately 1:1 molar ratio of the lithiated chiral amide to cyclopentyllithium. A variety of NMR experiments including diffusion-ordered NMR spectroscopy (DOSY) with diffusion coefficient-formula (D-FW) weight correlation analyses and other one- and two-dimensional NMR techniques allowed us to characterize the complex in solution. Solution state structures of the mixed aggregates of n-butyl, sec-butyllithium, isopropyllithium with lithiated (S)-N-ethyl-3-methyl-1-(triisopropylsilyloxy)butan-2-amine are also reported. Identical dimeric, ladder-type, mixed aggregates are the major species at a stoichiometric ratio of 1:1 lithium chiral amide to alkyllithium in toluene-d8 solution for all of the different alkyllithium reagents.
通过 X 射线衍射确定了含有来自 (S)-缬氨醇和环戊基锂的锂化 (S)-N-乙基-3-甲基-1-(三异丙基甲硅烷基氧基)丁-2-胺的混合聚集体的晶体结构。混合聚集体在固态中采用梯形结构。在含有锂化手性酰胺与环戊基锂摩尔比约为 1:1 的甲苯-d8 溶液中，梯形混合聚集体也是主要物种。包括扩散有序 NMR 光谱（DOSY）与扩散系数公式（D-FW）重量相关分析在内的各种 NMR 实验以及其他一维和二维 NMR 技术使我们能够对溶液中的配合物进行表征。还报道了锂化 (S)-N-乙基-3-甲基-1-(三异丙基甲硅烷基氧基)丁-2-胺与正丁基、仲丁基、异丙基锂的混合聚集体在甲苯-d8 溶液中的溶液态结构。在所有不同的烷基锂试剂中，对于锂手性酰胺与烷基锂的化学计量比为 1:1 的甲苯-d8 溶液中，相同的二聚体、梯形混合聚集体是主要物种。
