Synthesis of novel carbohydrate-based valine-derived formamide organocatalysts by CuAAC click chemistry and their application in asymmetric reduction of imines with trichlorosilane
作者:Xin Ge、Chao Qian、Xinzhi Chen
DOI:10.1016/j.tetasy.2014.10.003
日期:2014.11
organocatalysts combining carbohydrate and N-formyl-l-valine derivatives were prepared by CuII-catalyzed diazotransfer and CuI-catalyzed azide–alkyne 1,3-dipolar cycloaddition CuAACclickchemistry. It was found that the carbohydrate-based valine-derived formamide organocatalyst had high catalytic activity for the asymmetric reduction of imines with trichlorosilane. The reduction can proceed at room
An efficient proline-based homogeneous organocatalyst with recyclability
作者:Qiang Li、Yuan Li、Jingdong Wang、Yingjie Lin、Zhonglin Wei、Haifeng Duan、Qingbiao Yang、Fuquan Bai、Yaoxian Li
DOI:10.1039/c7nj03912c
日期:——
organocatalyst was developed for the asymmetric reduction of imines. This catalyst could be separated by cyclodextrin-modified Fe3O4@SiO2 magnetic nanoparticles and then released back into a fresh reaction for use more than seven times. Furthermore, a new catalytic mechanism was proposed and investigated through theoretical calculations.
在这项工作中,开发了均相有机催化剂用于亚胺的不对称还原。该催化剂可通过环糊精改性的Fe 3 O 4 @SiO 2磁性纳米颗粒分离,然后释放回新鲜反应中使用七次以上。此外,提出了一种新的催化机理,并通过理论计算进行了研究。
Chiral Brønsted Acid-Catalyzed Metal-Free Asymmetric Direct Reductive Amination Using 1-Hydrosilatrane
作者:Vladislav Skrypai、Sami E. Varjosaari、Fawwaz Azam、Thomas M. Gilbert、Marc J. Adler
DOI:10.1021/acs.joc.8b03073
日期:2019.5.3
The asymmetric direct reductive amination of prochiral ketones with aryl amines using 1-hydrosilatrane with a chiral Brønsted acid catalyst is reported. This is the first known example of chiral Brønsted acid-catalyzed asymmetric reductive amination using a silane as the hydride source. The reaction features a highly practical reducing reagent and proceeds efficiently at room temperature without a
<i>C</i>
<sub>2</sub>
‐Symmetric Bicyclic Bisborane Catalysts: Kinetic or Thermodynamic Products of a Reversible Hydroboration of Dienes
作者:Xian‐Shuang Tu、Ning‐Ning Zeng、Ru‐Ye Li、Yu‐Quan Zhao、De‐Zhen Xie、Qian Peng、Xiao‐Chen Wang
DOI:10.1002/anie.201808289
日期:2018.11.12
C2‐symmetric bicyclic bisborane catalysts by addition reactions of internal dienes with the Piers borane, HB(C6F5)2, and an analogue, HB(p‐C6F4H)2. The dependence of the addition pattern on the reaction temperature allowed us to selectively prepare two diastereomericcatalysts from a single diene precursor. The bisboranes prepared in situ exhibited excellent activity (turnover numbers up to 200 at −40 °C)
我们通过内部二烯与Piers硼烷HB(C 6 F 5)2和类似物HB(p- C 6 F 4 H)2的加成反应制备了新型的手性C 2对称双环双硼烷催化剂。加料方式对反应温度的依赖性使我们能够从单一的二烯前体中选择性地制备两种非对映体催化剂。原位制备的双硼烷在亚胺加氢反应中表现出出色的活性(在-40°C时的转换数高达200)和对映选择性(高达95% ee)。
Pinene-Derived Monodentate Phosphoramidites for Asymmetric Hydrogenation
the asymmetric hydrogenation of imines and olefins. The iridium-catalyzedhydrogenation of imines provided up to 81 % ee, whereas in the rhodium-catalyzed hydrogenation of functionalized olefinsenantioselectivities of up to 99 % ee were achieved. In this particular application, the different chiral elements of the ligand structure led to synergistic effects and the enantioselectivity is dominated by
基于蒎烯衍生的手性胺的亚磷酰胺配体已通过简单的程序以良好的产率制备。合成方案的关键步骤是对环状蒎烯-吡啶衍生物进行立体选择性氢化,产生(非对映异构)仲胺,仲胺被分离并用不同的氯亚磷酸酯处理以产生设想的亚磷酰胺。配体的绝对构型是在 NMR 分析的基础上确定的,并通过典型配体的硼烷加合物的 X 射线衍射分析得到证实。新配体用于亚胺和烯烃的不对称氢化。亚胺的铱催化氢化提供高达 81% ee,而在官能化烯烃的铑催化氢化中,实现了高达 99% ee 的对映选择性。