Pyridine undergoes addition of pinacolborane at 50 °C in the presence of a rhodium catalyst, giving N-boryl-1,2-dihydropyridine in a high yield. The selective 1,2-hydroboration also takes place in the reactions of substituted pyridines. In the reaction of 3-substituted pyridines, 3-substituted N-boryl-1,2-dihydropyridines are formed regioselectively.
在铑催化剂的存在下,吡啶在 50 °C 下加入频哪醇硼烷,以高产率得到 N-boryl-1,2-dihydropyridine。选择性的 1,2-硼氢化反应也发生在取代吡啶的反应中。在3-取代吡啶的反应中,3-取代的N-boryl-1,2-二氢吡啶区域选择性地形成。
Ni–O Cooperation versus Nickel(II) Hydride in Catalytic Hydroboration of <i>N</i>-Heteroarenes
作者:Jianguo Liu、Jia-Yi Chen、Mengjing Jia、Bangrong Ming、Jiong Jia、Rong-Zhen Liao、Chen-Ho Tung、Wenguang Wang
DOI:10.1021/acscatal.8b05136
日期:2019.5.3
An air-stable half-sandwich nickel(II) complex bearing a phosphinophenolato ligand, Cp*Ni(1,2-Ph2PC6H4O) (1), has been designed and synthesized for activation of HBpin and catalytic hydroboration of N-heteroarenes such as pyridine. Through addition of the H–B bond across the Ni–O bond, 1 reacts with HBpin to afford an 18-electron Ni(II)–H intermediate [H1(Bpin)] featuring an oxygen-stabilized boron
设计并合成了具有膦基酚基配体Cp * Ni(1,2-Ph 2 PC 6 H 4 O)(1)的空气稳定的半三明治镍(II)配合物。N-杂芳烃,例如吡啶。通过跨Ni-O键添加H-B键,1与HBpin反应,得到18电子Ni(II)-H中间体[H 1((Bpin)]的特征在于氧稳定的硼部分,其易于还原吡啶类似物以得到1,2-硼氢化产物,从而在温和条件下完成催化循环。1和Cp * NiH(PPh 3)(3 H)在催化硼氢化反应中的活性存在明显差异,从而证明了膦基酚基配体传递硼基的必要性。后者缺乏功能性氧原子,并且对于催化过程是惰性的。
Catalytic 1,2-Regioselective Dearomatization of N-Heteroaromatics via a Hydroboration
作者:Heng Liu、Maxim Khononov、Moris S. Eisen
DOI:10.1021/acscatal.8b00074
日期:2018.4.6
catalyzed highly 1,2-regioselective dearomatization of pyridines via a hydroboration process is reported herein. Twelve different kinds of meta- and para-substituted pyridines are applicable to this reaction, giving the corresponding N-boryl-1,2-dihydropyridine products in high yields. Other N-heteroaromatic compounds, such as benzo-fused N-heterocycles, pyrazines, pyrimidines, 1,3,5-triazine, and benzothiazole
甲基or和氢化物配合物(C 5 Me 5)2 ThMe 2和[(C 5 Me 5)2 Th(H)(μ-H)] 2通过氢硼化过程催化吡啶的高度1,2-区域选择性脱芳香化反应。在此报告。十二种间位和对位取代的吡啶适用于该反应,给出相应的N-硼基-1,2-二氢吡啶产物的收率高。还发现其他N-杂芳族化合物,例如苯并稠合的N-杂环,吡嗪,嘧啶,1,3,5-三嗪和苯并噻唑也具有高化学选择性的硼氢化。包括同位素效应研究在内的动力学表明,催化剂,吡啶和频哪醇硼烷的浓度具有一级依赖性,而脱芳香化的最终产物的释放是速率确定的步骤。在化学计量反应和动力学研究的基础上提出了一个合理的机制。
Atom-efficient regioselective 1,2-dearomatization of functionalized pyridines by an earth-abundant organolanthanide catalyst
作者:Alexander S. Dudnik、Victoria L. Weidner、Alessandro Motta、Massimiliano Delferro、Tobin J. Marks
DOI:10.1038/nchem.2087
日期:2014.12
synthesis. Dearomatization of pyridine derivatives is an important transformation to access a wide range of valuable nitrogenous natural products, pharmaceuticals and materials. Here, we report an efficient 1,2-regioselective organolanthanide-catalysed pyridine dearomatization process using pinacolborane, which is compatible with a broad range of pyridines and functional groups and employs equimolar