2,3,4,6-四氟苯硼酸 以
neat (no solvent) 为溶剂,
生成 tris(2,3,4,6-tetrafluorophenyl)boroxine
参考文献:
名称:
摘要:
A general preparative procedure for polyfluorinated aryl(dihydroxy)boranes C6H5-nFnB(OH)(2) (n = 3 - 5) is described. Polyfluorinated aryl(dihydroxy)boranes are easily dehydrated to the corresponding tri(aryl)boroxins (C6H5-nFnBO)(3) by thermal or chemical treatment. The property of the acids C6H5-nFnB(OH)(2) to condensate depends on the number and on the position of the fluorine atoms in the aryl group. Examples of both classes of boron compounds were isolated as pure individuals and characterized by multinuclear NMR spectroscopy.
An “On-Cycle” Precatalyst Enables Room-Temperature Polyfluoroarylation Using Sensitive Boronic Acids
作者:Liye Chen、Haydn Francis、Brad P. Carrow
DOI:10.1021/acscatal.8b00341
日期:2018.4.6
fluorinated arylboronic acid building blocks in cross-coupling has remained challenging, because of their acute base sensitivity. We report a general solution to this problem using a true catalytic intermediate, Pd(PAd3)(p-FC6H4)Br, as a uniquely effective “on-cycle” precatalyst that allows Suzuki–Miyaura coupling to occur much faster than even the most severe protodeboronation side reactions. Control of boron
交叉偶联中使用氟化芳基硼酸结构单元仍然具有挑战性,因为它们具有敏锐的碱敏感性。我们报告了使用真正的催化中间体Pd(PAd 3)(p -FC 6 H 4)Br作为唯一有效的“循环”预催化剂,可以使Suzuki-Miyaura偶联发生的速度快得多的一般解决方案。即使是最严重的原去硼副反应。还发现控制活性酸形式和休眠酯形式之间的硼形态在平衡催化速率与试剂分解之间起着至关重要的作用。该方法与任何氟化模式,对碱不稳定的官能团以及一系列溴(杂)芳烃均兼容。
“Cationic” Suzuki–Miyaura Coupling with Acutely Base-Sensitive Boronic Acids
作者:Liye Chen、Daniel R. Sanchez、Bufan Zhang、Brad P. Carrow
DOI:10.1021/jacs.7b07687
日期:2017.9.13
base-promoted protodeboronation of polyfluoroaryl and heteroaryl boronicacids complicates their use in Suzuki-Miyaura coupling (SMC) because a base is generally required for catalysis. We report a "cationic" SMC method using a PAd3-Pd catalyst that proceeds at rt in the absence of a base or metal mediator. A wide range of sensitive boronicacids, particularly polyfluoroaryl substrates that are poorly compatible
Base-Catalyzed Aryl-B(OH)<sub>2</sub> Protodeboronation Revisited: From Concerted Proton Transfer to Liberation of a Transient Aryl Anion
作者:Paul A. Cox、Marc Reid、Andrew G. Leach、Andrew D. Campbell、Edward J. King、Guy C. Lloyd-Jones
DOI:10.1021/jacs.7b07444
日期:2017.9.20
Pioneering studies by Kuivila, published more than 50 years ago, suggested ipso protonation of the boronate as the mechanism for base-catalyzed protodeboronation of arylboronic acids. However, the study was limited to UV spectrophotometric analysis under acidic conditions, and the aqueous association constants (Ka) were estimated. By means of NMR, stopped-flow IR, and quenched-flow techniques, the
Kuivila于50年前发表的开创性研究表明,硼酸酯的ipso质子化是芳基硼酸的碱催化原脱硼硼烷的机理。但是,该研究仅限于酸性条件下的紫外分光光度法分析,并且估计了水的缔合常数(K a)。借助于NMR,停止流IR和骤冷流技术,现在已经在70°C的二恶烷水溶液中,在pH> 13的条件下,测定了30种不同的芳基硼酸的碱催化原硼酸脱氢反应的动力学。研究中包括C 6 H n F (5- n) B(OH)2的所有20个异构体半衰期跨越9个数量级:<3毫秒至6.5个月。在具有pH率分布,对组合ķ一个和Δ小号⧧值,动力学同位素效应(2 H,10 B,13 C),线性自由能的关系,并密度泛函理论计算,我们已经确定,涉及一种机械制度硼酸酯的单分子杂化与协同的ipso质子化/ C–B裂解竞争。芳基硼酸的相对路易斯酸度与它们的原脱硼氢硼酸速度不相关,特别是当存在邻位取代基时。值得注意的是,3,5-二硝基苯基硼酸
Stopped‐Flow
<sup>19</sup>
F NMR Spectroscopic Analysis of a Protodeboronation Proceeding at the Sub‐Second Time‐Scale
作者:Ran Wei、Andrew M. R. Hall、Richard Behrens、Mark S. Pritchard、Edward J. King、Guy C. Lloyd‐Jones
DOI:10.1002/ejoc.202100290
日期:2021.5.7
The protodeboronation of a reactive boronate has been analyzed by stopped‐flow 19F NMR spectroscopy. The study shows how the consideration of longitudinal relaxation, pre‐magnetization, mixing, heat transfer, pulse angle, interscan delay, and spectral interleaving, allows the kinetics of a reaction with a half‐life of 0.12 seconds to be measured by NMR.
反应性硼酸酯的原去硼酸酯化已通过停止流19 F NMR光谱法进行了分析。研究表明,通过考虑纵向弛豫,预磁化,混合,传热,脉冲角,扫描间延迟和光谱交织,可以通过NMR测量半衰期为0.12秒的反应动力学。
A new application of (polyfluoroorgano)trifluoroborate salts: the palladium-catalysed cross-coupling reaction with substituted benzenediazonium tetrafluoroborates
作者:Hermann-Josef Frohn、Nicolay Yu. Adonin、Vadim V. Bardin、Vladimir F. Starichenko
DOI:10.1016/s0022-1139(02)00157-4
日期:2002.10
influence of the number and the position of the fluorine atoms in the (polyfluorophenyl)trifluoroborate salts on the reactivity in the coupling reaction was elucidated. In addition to (polyfluorophenyl)trifluoroborate salts, the cross-coupling was expanded to a first example of a perfluoroalkenyl reagent. K[CF2CFBF3] reacted with [4-FC6H4N2][BF4] and formed CF2CF–C6H4F-4.
首次(多氟有机)三氟硼酸盐,即K [C 6 F 5 BF 3 ],K [C 6 HF 4 BF 3 ](所有三种异构体),K [3,4,5-C 6 H 2 F 3 BF 3 ]和K [CF 2 CFBF 3 ]的主要应用于作为试剂用于钯催化的交叉偶联反应。由K [C 6 H 5– n F n获得了一系列多氟联苯C 6 H 5– n F n –C 6 H 4 X-4'BF 3 ]和底物[4-XC 6 H 4 N 2 ] [BF 4 ]在Pd催化剂的存在下。阐明了(多氟苯基)三氟硼酸盐中氟原子的数目和位置对偶联反应中反应性的影响。除了(聚氟苯基)三氟硼酸盐以外,交叉偶联扩展为全氟烯基试剂的第一个实例。K [CF 2 CFBF 3 ]与[4-FC反应6 ħ 4 Ñ 2 ] [BF 4 ]和形成CF 2 CF-C 6 H ^ 4 F-4。