Eight new linear octiphenyls containing two or three kinds of linkage were synthesized by the Ullmann homo-coupling reaction of iodoquaterphenyl. Among them, five compounds were alternatively synthesized by the Kharash-type Grignard cross-coupling of biphenylylmagnesium bromide and diiodoquaterphenyl or of terphenylylmagnesium iodide and diiodoquaterphenyl in the presence of bis (acetylacetonato) nickel (II). Spectral studies proved that the octiphenyls thus prepared displayed highly characteristic infrared, ultraviolet, and nuclear magnetic resonance spectra. Empirical Huckel molecular orbital calculations of the longest wavelength absorption bands of the octiphenyls were also performed. The calculated and observed wavelengths were in rather good agreement, except for the cases of two compounds.
A series of twenty-seven polyphenyls, including quater-to sexiphenyls, was synthesized by the cross-coupling reaction of aryl Grignard reagents with arylene diiodides in the presence of bis (acetylacetonato) nickel (II). Twenty of them were obtained in fairly good yields (50-95%) under mild conditions at temperatures below ca. 60°C in ether-benzene solution within a few hours. In the cases of the remaining seven polyphenyls, however, lower yields (1-34%) were inevitable owing to the sterically crowded geometry of the reactant (s). Thus, the Kharash-type Grignard cross-coupling reaction was proved to be an efficient and convenient method for synthesizing a variety of polyphenyls, except in the cases of reactants with remarkably crowded geometry. The infrared, ultraviolet, and proton magnetic resonance spectral properties of several polyphenyls including three new compounds, 3-(2-biphenylyl)-o-quaterphenyl, 6'-(3-biphenylyl)-m-quaterphenyl, and 3, 4'-di (2-biphenylyl) biphenyl, are presented and discussed.
Role of the Base and Control of Selectivity in the Suzuki-Miyaura Cross-Coupling Reaction
作者:Carlos F. R. A. C. Lima、Ana S. M. C. Rodrigues、Vera L. M. Silva、Artur M. S. Silva、Luís M. N. B. F. Santos
DOI:10.1002/cctc.201301080
日期:2014.3.11
The outcome of the Suzuki–Miyaura cross‐coupling for the direct competition reaction between two boronic acids was evaluated under routine synthesis conditions. The reactionselectivity was found to depend on the amount of the base used, with fewer bases favoring the reactivity of the boronic acid with lower pKa (stronger acid). The dependence of the reactionselectivity on base stoichiometry was found
在常规合成条件下,对两个硼酸之间直接竞争反应的Suzuki-Miyaura交叉偶联的结果进行了评估。发现反应选择性取决于所用碱的量,较少的碱有利于硼酸具有较低的p K a(强酸)的反应性。发现反应选择性对碱化学计量的依赖性随竞争性硼酸的p K a值差异的增加而增加。这些结果证实了酸碱化学反应与Suzuki-Miyaura反应催化循环之间的关系。此外,结果表明,在这些特定条件下,最易发生金属转移反应的有机硼是硼酸根阴离子R B(OH)3 - ,而不是中性硼酸ř B(OH)2。因此,碱在反应机理中的主要作用是通过将硼酸转化为相应的有机硼酸盐来提高硼酸对Pd-卤化物络合物的反应性。另外,硼酸是重要的反应副产物,它会影响Suzuki反应的选择性,因为它在反应介质中的逐渐形成会干扰酸碱平衡。
Studies of Polyphenyls and Polyphenylenes. I. The Syntheses and Infrared and Electronic Spectra of Several Sexiphenyls
作者:Eiichi Ibuki、Shigeru Ozasa、Kazue Murai
DOI:10.1246/bcsj.48.1868
日期:1975.6
Ullmann reaction of iodobiphenyl and diiodobiphenyl. Infrared studies indicated that the fine structure in the 780–810 cm−1 region suggests the presence of consecutive m-phenylene units, and that the positions of the strong or medium bands in the 820–840 cm−1 region indicate approximately the number of continuous p-phenylene units. The electronic spectra commonly displayed a prominent E-band in the narrow
通过碘联苯和二碘联苯的乌尔曼反应合成了七种线性六联苯。红外研究表明,780-810 cm-1 区域的精细结构表明存在连续的间亚苯基单元,820-840 cm-1 区域中强或中带的位置表明大约有连续对亚苯基单元。电子光谱通常在 192-207 nm 的狭窄区域显示出突出的 E 带。260 nm 以上的强 K 带被认为表明存在一个或多个对亚苯基单元。
Acid-catalyzed rearrangements in arenes: interconversions in the quaterphenyl series
作者:Sarah L Skraba-Joiner、Carter J Holt、Richard P Johnson
DOI:10.3762/bjoc.15.258
日期:——
equilibrium product. This isomer is unchanged by the reaction conditions and all other quaterphenyl isomers rearrange to m,p' as the dominant or sole product. DFT computations with inclusion of implicit solvation support a complex network of phenyl and biphenyl shifts, with barriers to rearrangement in the range of 10–21 kcal/mol. Consistent with experiments, the lowest energy arenium ion located on this
芳烃通过中间性经历的苯基,烷基,卤素和其它基团的重排的本位arenium其中质子连接在相同碳作为迁移取代基的离子。此处已研究了六个四苯基异构体之间的相互转化,作为线性聚苯基重排的模型。所有反应均在微波反应器中于150°C的二氯乙烷中的1 M CF 3 SO 3 H(TfOH)中进行30-60分钟,并通过高场NMR分析评估产物的形成。在这些反应条件下,m,p′-四苯基为平衡产物。该异构体在反应条件下保持不变,所有其他四苯基异构体均重排为m,p'作为主导产品或唯一产品。包含隐含溶剂化的DFT计算支持复杂的苯基和联苯转移网络,重排障碍在10–21 kcal / mol的范围内。与实验一致,位于该表面上的最低能量的芳族离子是由于m,p'-四苯基的质子化所致。这支持了基于碳正离子能量的热力学控制。