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。
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。
Manganese‐Catalyzed Hydroborations with Broad Scope
作者:Pradip Ghosh、Axel Jacobi von Wangelin
DOI:10.1002/anie.202103550
日期:2021.7.12
synthetic manipulation and chemical valorization. The applications of catalytic hydrofunctionalization benefit from the use of liquid reducing agents and operationally facile setups. Metal-catalyzed hydroborations provide a highly prolific platform for reductive valorizations of stable C=X electrophiles. Here, we report an especially facile, broad-scope reduction of various functions including carbonyls
Cobalt-catalyzed double hydroboration of pyridines
作者:Finn Höeg、Lea Luxenberger、Andrey Fedulin、Axel Jacobi von Wangelin
DOI:10.1039/d3sc05418g
日期:——
acetylation afforded the bench-stable borylated N-acetyl tetrahydropyridines in good yields. The synthetic utility of this procedure was demonstrated by a gram-scale double hydroboration–acetylation sequence followed by chemical diversification. Mechanistic experiments indicated metal–ligandcooperativity involving ligand-centered C–H activation and the intermediacy of a cobalt(III) hydride species.
钴( II )络合物是从模块化膦吡啶酸平台制备的,并应用于吡啶的硼氢化反应。合成上有用但具有挑战性的四氢吡啶衍生物的双硼氢化反应已成功进行,具有高活性和区域控制。这种新方法使得能够从商业吡啶和频哪醇硼烷(HBpin)直接合成N-杂环烯丙基硼酸酯。一锅乙酰化以良好的收率提供了实验室稳定的硼基化N-乙酰基四氢吡啶。该过程的合成效用通过克级双硼氢化-乙酰化序列以及随后的化学多样化得到了证明。机理实验表明金属-配体协同作用涉及以配体为中心的C-H活化和氢化钴( III )物种的中介作用。