High-Turnover Aromatic C–H Borylation Catalyzed by POCOP-Type Pincer Complexes of Iridium
作者:Loren P. Press、Alex J. Kosanovich、Billy J. McCulloch、Oleg V. Ozerov
DOI:10.1021/jacs.6b03656
日期:2016.8.3
presence of stoichiometric quantities of sacrificial olefin, which is hydrogenated to consume the H2 equivalents generated in the borylation of C-H bonds with HBpin. Smaller olefins such as ethylene or 1-hexene were more advantageous to catalysis than sterically encumbered tert-butylethylene (TBE). Olefin hydroboration is a competing side reaction. The synthesis and isolation of multiple complexes potentially
已经证明了使用 Ir 的 POCOP 型钳形复合物对芳烃与 HBpin(pin = 频哪酸酯)的催化 CH 硼化,在某些情况下转换数超过 10 000。CH 活化的选择性基于空间偏好,并且在很大程度上反映了在其他 Ir 硼化催化剂中发现的选择性。(POCOP)Ir 系统中的催化取决于化学计量数量的牺牲烯烃的存在,该牺牲烯烃被氢化以消耗在 CH 键与 HBpin 的硼酸化中产生的 H2 等价物。较小的烯烃如乙烯或 1-己烯比空间阻碍的叔丁基乙烯 (TBE) 更有利于催化。烯烃硼氢化反应是一种竞争性副反应。可能与催化相关的多种复合物的合成和分离允许检查几个关键的基本反应。这些实验表明,催化中的 CH 活化步骤表面上涉及将芳族 CH 键氧化加成到三配位 (POCOP) Ir 物质上。烯烃对于获得这种 14 电子单价 Ir 中间体在机械上至关重要。此处 Ir(I) 处的 CH 活化与使用由中性双齿配体支持的最先进
Rhodium Boryl Complexes in the Catalytic, Terminal Functionalization of Alkanes
作者:John F. Hartwig、Kevin S. Cook、Marko Hapke、Christopher D. Incarvito、Yubo Fan、Charles Edwin Webster、Michael B. Hall
DOI:10.1021/ja045090c
日期:2005.3.1
P(p-Tol)(3) to generate the conventional rhodium(III) species CpRh(PEt(3))(H)(Bpin) (4) and CpRh[P(p-tol)(3)](Bpin)(2) (5). Compounds 2 and 3 also react with alkanes and arenes to form alkyl- and arylboronate esters at temperatures similar to or below those of the catalyticborylation of alkanes and arenes. Further, these compounds were observed directly in catalytic reactions. The enthalpies and free energies
Nickel-catalyzed borylation of arenes and indoles via C–H bond cleavage
作者:Takayuki Furukawa、Mamoru Tobisu、Naoto Chatani
DOI:10.1039/c5cc01378j
日期:——
The first nickel-catalyzed method for the borylation of carbon–hydrogen bonds in arenes and indoles is described. The use of an N-heterocyclic carbene ligand is essential for an efficient reaction, with an N-cyclohexyl-substituted derivative being optimal. This method is readily applied to the gram scale synthesis of 2-borylindole.
platinum-catalyzed borylation of aromatic C–H bonds. N-Heterocyclic carbene-ligated platinum catalysts are found to be efficient catalysts for the borylation of aromatic C(sp2)–H bonds when bis(pinacolato)diboron is used as the boron source. The most remarkable feature of these Pt catalysts is their lack of sensitivity towards the degree of steric hindrance around the C–H bonds undergoing the borylation reaction