Pd 催化的苯酚烯丙基碳酸酯的不对称烯丙基烷基化 (AAA) 是构建烯丙基 CO 键的有效策略,允许获得高达 98% ee 的手性色满。详细探讨了 pH 值的影响和烯烃几何结构的影响,以及取代模式对 ee 和手性色满的绝对构型的影响。这些观察结果表明一种机制涉及反应性更强的 pi-烯丙基钯非对映体中间体的环化作为对映体区分步骤(Curtin-Hammett 条件)。这种方法导致了维生素 E 核心的对映选择性合成,首次对 (+)-clusifoliol 和 (-)-siccanin 进行了对映选择性全合成,以及合成了 (+)-红花紫杉酸 A 的高级中间体。
Total Synthesis of (<i>R,R,R</i>)-γ-Tocopherol through Cu-Catalyzed Asymmetric 1,2-Addition
作者:Zhongtao Wu、Syuzanna R. Harutyunyan、Adriaan J. Minnaard
DOI:10.1002/chem.201404458
日期:2014.10.27
Based on the asymmetric copper‐catalyzed 1,2‐addition of Grignard reagents to ketones, (R,R,R)‐γ‐tocopherol has been synthesized in 36 % yield over 12 steps (longest linear sequence). The chiral center in the chroman ring was constructed with 73 % ee by the 1,2‐addition of a phytol‐derived Grignard reagent to an α‐bromo enone prepared from 2,3‐dimethylquinone.
Persistent radical cation solutions from the reaction between aromatics and bromine, chlorine or iodine chloride in 1,1,1,3,3,3-hexafluoropropan-2-ol at room temperature
作者:Lennart Eberson、Michael P. Hartshorn、Finn Radner、Ola Persson
DOI:10.1039/cc9960000215
日期:——
The treatment of reactive aromatic compounds by bromine, chlorine or iodine chloride in 1,1,1,3,3,3-hexafluoropropan-2-ol gives persistent solutions of the corresponding radical cations, in spite of the fact that a nucleophile, a chloride or bromide ion, is simultaneously generated.
Radical cation mechanism of aromatic halogenation by halogens or iodine chloride in 1,1,1,3,3,3-hexafluoropropan-2-ol
作者:Lennart Eberson、Michael P. Hartshorn、Finn Radner、Ola Persson
DOI:10.1039/a705393b
日期:——
The reaction between aromatic compounds ArH and halogenating agents, viz. iodine chloride, chlorine, bromine, iodine, N-bromosuccinimide and N-chlorosuccinimide, in 1,1,1,3,3,3-hexafluoropropan-2-ol (HFP) has been investigated. EPR spectroscopy established that these reagents produced persistent radical cations ArH˙+ from ArH with Erev(ArH˙+/ArH) up to 1.6, 1.3, 1.4, 1.1, 1.5 and 1.2 V vs. Ag/AgCl
McHale et al., Journal of the Chemical Society, 1959, p. 3358,3361
作者:McHale et al.
DOI:——
日期:——
Synthesis of murrayaquinone A and analogues via ring-closing C–H arylation
作者:Robin B. Bedford、John G. Bowen、Amanda L. Weeks
DOI:10.1016/j.tet.2013.02.055
日期:2013.6
A compact synthesis of Murrayaquinone A is reported, based on sequential Buchwald-Hartwig amination/annulative C-H activation followed by oxidation of the intermediate carbazole. The methodology can be readily extended to other analogues with electron-rich quinone rings. (C) 2013 Elsevier Ltd. All rights reserved.