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。
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
While numerous organo(metallic)catalyst systems were documented for dearomative hydroboration of N‐aromatics, alkoxide base catalysts have not been disclosed thus far. Described herein is the first example of alkoxide‐catalyzed hydroboration of N‐heteroaromatics including pyridines, providing a broad range of reduced N‐heterocycles with high efficiency and selectivity. Mechanistic studies revealed
Regioselective Hydroboration and Hydrosilylation of N-Heteroarenes Catalyzed by a Zinc Alkyl Complex
作者:Xinxin Wang、Yu Zhang、Dan Yuan、Yingming Yao
DOI:10.1021/acs.orglett.0c02082
日期:2020.7.17
Readily available zinc alkylcomplexes showed good activity and regioselectivity in catalyzing hydroboration and hydrosilylation of N-heteroarenes. Hydroboration of benzo-fused N-heterocycles gave exclusive 1,2-addition products in 80–97% yields. Reactions of pyridines afforded a mixture of 1,2-, 1,4-, and 1,6-products in yields of 55–95%, with 1,2-dihydropyridine as the main product. Bis-hydrosilylation
Regioselective 1,4-hydroboration of pyridines catalyzed by an acid-initiated boronium cation
作者:Evan N. Keyzer、Sky S. Kang、Schirin Hanf、Dominic S. Wright
DOI:10.1039/c7cc04988a
日期:——
The reaction of the commercially available ammonium salt NH4BPh4 with a pyridine-activated pinacolborane species generates a boronium cation that facilitates the 1,4-selective hydroboration of pyridines in polar solvents. This catalytic reaction is amenable to a host of reactive functional groups and provides access to sterically bulky hydroboration products, previously inaccessible by metal-free routes