Disodium Salts of Pseudoephedrine-Derived Myers Enolates: Stereoselectivity and Mechanism of Alkylation.
Disodium Salts of Pseudoephedrine-Derived Myers Enolates: Stereoselectivity and Mechanism of Alkylation.
复制标题
伪麻黄碱衍生的迈尔斯烯醇化物的二钠盐：立体选择性和烷基化机制。
DOI：
10.1021/jacs.9b08176
复制
发表时间：
2019
影响因子：
15
通讯作者：
Collum,DavidB
中科院分区：
文献类型：
--
作者：
Zhou,Yuhui;Keresztes,Ivan;MacMillan,SamanthaN;Collum,DavidB
在THF溶液中使用二异丙基氨基钠（NaDA）生成假麻黄碱衍生的双阴离子迈尔斯烯醇化物。二钠盐的反应性和选择性在很大程度上反映了二锂盐的反应性和选择性，但不需要大量过量的无机盐（LiCl）或强制稀释溶液。二钠盐需要仔细控制温度，以排除有害的聚集体老化效应，这些效应可追溯到聚集体结构的变化和介入的O-烷基化。结构研究和密度泛函理论（DFT）计算表明，占主导地位的高度对称多面体完全不同的锂类似物。在过量NaDA的情况下未观察到烯醇化物-NaDA混合聚集体。速率研究表明，烷基化机制涉及干预四聚体单体预平衡，然后由四溶剂化单体的限速烷基化。DFT计算进行了探索立体化学的可能影响。衍生自在环境温度下老化的样品的晶体含有六个双阴离子亚基和两个单阴离子（仅烷氧基）亚基。本文介绍了一种制备NaDA浓溶液的新方法。
Pseudoephedrine-derived dianionic Myers enolates were generated using sodium diisopropylamide (NaDA) in THF solution. The reactivities and selectivities of the disodium salts largely mirror those of the dilithium salts but without the requisite large excesses of inorganic salts (LiCl) or mandated dilute solutions. The disodium salts require careful control of temperature to preclude deleterious aggregate aging effects traced to changes in the aggregate structure and intervening O-alkylations. Structural studies and density functional theory (DFT) computations show a dominant highly symmetric polyhedron quite different from the lithium analogue. No enolate–NaDA mixed aggregates are observed with excess NaDA. Rate studies show an alkylation mechanism involving an intervening tetramer–monomer pre-equilibrium followed by rate-limiting alkylation of tetrasolvated monomers. DFT computations were conducted to explore the possible influences on stereochemistry. A crystal deriving from samples aged at ambient temperature contains six dianionic subunits and two monoanionic (alkoxide-only) subunits. A new preparation of concentrated solutions of NaDA in THF solution is described.
IL-1 的生理、代谢和免疫作用：Kluger, M.J., J.J.
DOI：
--
发表时间：
1987
期刊：
影响因子：
--
作者：
F. Borek
通讯作者：
F. Borek