Pyrrolidine-derived functionalizedchiralionicliquids (FCILs) have been found to catalyzeasymmetric S N 1 α-alkylations of ketones and aldehydes with up to 99 % yield, >99:1 dr and 87 % ee. The FCIL catalysts enable S N 1 α-alkylations of cyclicketones, particularly of 3- and 4-substituted cyclohexanones with excellent diastereoselectivity and good enantioselectivity, featuring unprecedented desymmetrization
已发现吡咯烷衍生的官能化手性离子液体 (FCIL) 可催化酮和醛的不对称 SN 1 α-烷基化反应,产率高达 99%,>99:1 dr 和 87% ee。FCIL 催化剂使环酮,特别是 3-和 4-取代环己酮的 SN 1 α-烷基化具有优异的非对映选择性和良好的对映选择性,为这些类型的不对称反应提供了前所未有的去对称化和动力学拆分过程。介绍了这项研究的全部细节以及提议的烯胺过渡态。
Asymmetric S<sub>N</sub>1 α-Alkylation of Cyclic Ketones Catalyzed by Functionalized Chiral Ionic Liquid (FCIL) Organocatalysts
Ionicliquid works better: The first intermolecular asymmetric α‐alkylation of cyclicketones was realized by using functionalizedchiralionicliquids as catalysts. The reaction proceeded with good to excellent yields and high ee. Highly stereoselective desymmetrization of 4‐substituted cyclohexanones with >99:1 d.r. and up to 87 % ee were achieved by using this protocol.
How Constant Are Ritchie's “Constant Selectivity Relationships”? A General Reactivity Scale for n-, π-, and σ-Nucleophiles
作者:Shinya Minegishi、Herbert Mayr
DOI:10.1021/ja021010y
日期:2003.1.1
literature data for the reactions of these nucleophiles with other carbocations to yield electrophilicity parameters E for tritylium, tropylium, and xanthylium ions. While the E parameters for tropylium and xanthylium ions appear to be generally applicable, it is demonstrated that the E parameters of tritylium ions can be used to predict reactivities toward n-nucleophiles as well as hydride transfer
已在 20 摄氏度确定了二苯甲基离子 (Ar(2)CH(+)) 与 n-亲核试剂的 82 次反应的动力学。通过方程 log k = s(N + E) 进行评估,得出反应性参数 N 和 s对于 15 个 n-亲核试剂(水、氢氧化物、胺等)。除了水 (s = 0.89) 和 (-)SCH(2)CO(2)(-) (s = 0.43) 之外的所有亲核试剂都具有非常相似的斜率参数 (0.52 < s < 0.71),表明大多数 n-亲核试剂大致遵循 Ritchie 的常数选择性关系(s = 常数)。水的不同斜率参数被认为是 1986 年报道的偏离 Ritchie 关系的主要原因。 二苯鎓离子与 n-亲核试剂(H(2)O 除外)反应速率常数的相关分析里奇的基础' s 方程 log k = N(+) + log k(0) 产生一组经过统计验证的 N(+) 参数用于 Ritchie 型亲核试剂和 log k(0)
empirical nucleophilicity parameter, and s is a nucleophile-specific slope parameter. From plots of log k versus E of the benzhydrylium ions are derived the solventnucleophilicity parameters s and N, the latter of which are designated as N1 to emphasize that their use in the quoted correlation equation gives rise to first-order rate constants. A linear correlation between N1 and Kevill's solvent nucleophilicity
二苯甲基鎓离子(二芳基碳鎓离子)与不同组成的溶剂混合物(水/乙腈、甲醇/乙腈、乙醇/乙腈、乙醇/水和三氟乙醇/水)的反应速率已通过常规紫外-可见光谱法测定、停流方法和激光闪光技术。已经表明,一阶速率常数遵循先前公布的关系 log k(20°C) = s(N + E),其中 E 是经验亲电性参数,N 是经验亲核性参数,s 是亲核试剂特异性斜率参数。从二苯鎓离子的 log k 与 E 的关系图推导出溶剂亲核性参数 s 和 N,后者被指定为 N1 以强调它们在引用的相关方程中的使用会产生一阶速率常数。报告了 N1 和基于 S-甲基二苯并噻吩鎓离子的 Kevill 溶剂亲核性 NT 之间的线性相关性,这允许将两组数据相互转换。由于 N1 值与之前报道的 pi 系统 (www.cup.uni-muenchen.de/oc/mayr/) 的亲核参数 N 直接相当,因此具有溶剂分解生成的碳正离子的 Friedel-Crafts