Spin-Center Shift-Enabled Direct Enantioselective α-Benzylation of Aldehydes with Alcohols
作者:Eric D. Nacsa、David W. C. MacMillan
DOI:10.1021/jacs.7b12768
日期:2018.3.7
two-electron pathways. We report herein an enantioselective α-benzylation of aldehydes using alcohols as alkylating agents based on the mechanistic principle of spin-center shift. This strategy harnesses the dual activation modes of photoredox and organocatalysis, engaging the alcohol by SCS and capturing the resulting benzylic radical with a catalytically generated enamine. Mechanistic studies provide
大自然通常使用醇作为离去基团,因为 DNA 生物合成依赖于通过自由基介导的“自旋中心转移”(SCS)机制从核糖核苷二磷酸中去除水。然而,由于醇在双电子途径中的低反应性,醇在合成化学中作为烷化剂仍然没有得到充分利用。我们在此报告了基于自旋中心位移的机械原理,使用醇作为烷化剂的醛的对映选择性 α-苄基化。该策略利用光氧化还原和有机催化的双重激活模式,通过 SCS 与醇结合,并用催化生成的烯胺捕获产生的苄基自由基。机理研究为 SCS 作为关键的基本步骤提供了证据,确定了竞争反应的起源,
Diarylamines with the Neighboring Pyridyl Group: Synthesis and Modulation of the Amine Functionality via Intramolecular H-Bonding
作者:Tatiana V. Magdesieva、Oleg A. Levitskiy、Ivan A. Klimchuk、Yuri K. Grishin、Vitaly A. Roznyatovsky、Boris N. Tarasevich
DOI:10.1055/a-1683-0315
日期:2022.3
obtained via Cu-assisted reductiveamination of the ortho-2-pyridylarylboronic acids. Comparative analysis of the spectral and electrochemical data obtained for new diarylamines and their pyridyl-free counterparts revealed the intramolecular H-bond (IMHB) formation which significantly influences the properties of the amino group. The electron density at the N atom of the amino group is increased due
通过邻-2-吡啶基芳基硼酸的Cu辅助还原胺化获得新的含吡啶基的二芳胺。对新二芳基胺及其无吡啶基对应物获得的光谱和电化学数据的比较分析揭示了分子内 H 键 (IMHB) 的形成,这显着影响了氨基的性质。由于 N-H 键的部分弱化,氨基的 N 原子处的电子密度增加,尽管 BDE 和 H 原子提取的活化能由于两个 N 原子的螯合作用而增加。与不含吡啶基的对应物相比,含邻吡啶基的二芳基胺更容易被氧化;氧化电位值的变化与分子内氢键的强度相关,可以通过在吡啶基或苯环中插入取代基来调节。即使在具有显着 H 受体能力的极性溶剂(如 DMSO)中,IMHB 也保留,但可以在甲醇中被破坏,证明有利于 H 键的动态性质。
Catalytic meta-selective C–H functionalization to construct quaternary carbon centres
作者:Andrew J. Paterson、Sahra St John-Campbell、Mary F. Mahon、Neil J. Press、Christopher G. Frost
DOI:10.1039/c5cc03951g
日期:——
A ruthenium catalyzed meta-selective C–H functionalization of 2-phenylpyridines with tertiary halides is described to establish challenging quaternary carbon centres in a regioselective manner. Preliminary studies suggest the C–H functionalization proceeds through a radical process directed via a remote σ-activation.
<i>meta</i>
‐Selective C−H Activation of Arenes at Room Temperature Using Visible Light: Dual‐Function Ruthenium Catalysis
作者:Arunachalam Sagadevan、Michael F. Greaney
DOI:10.1002/anie.201904288
日期:2019.7.15
Ruthenium‐catalyzedmeta‐C−H activation of arenes at roomtemperature is reported to proceed under blue‐light irradiation. A variety of heteroarenes are compatible with this photochemical process, which leads to the corresponding meta C−C coupling products in good to very good yields. Initial mechanistic studies suggest a single‐electron transfer process occurs between a photoexcited RuII‐cyclometalated
The present invention is directed to compounds of formula I and pharmaceutically acceptable salts, esters, and prodrugs thereof which are inhibitors of JAK kinase. The present invention is also directed to intermediates used in making such compounds, the preparation of such a compound, pharmaceutical compositions containing such a compound, methods of inhibition JAK kinase activity, methods of inhibition the platelet aggregation, and methods to prevent or treat a number of conditions mediated at least in part by JAK kinase activity, such as undesired thrombosis and Non Hodgkin's Lymphoma.