traditional C −C cross‐coupling reactions they have been rarely used and Pd catalysts usually give a superior performance. Herein we report that in situ formed gold metal nanoparticles are highly active catalysts for the crosscoupling of allylstannanes and activated alkylbromides to form C −C bonds. Turnover numbers up to 29 000 could be achieved in the presence of active carbon as solidsupport, which allowed
Determination of Rate Constants in the Carbocationic Polymerization of Styrene: Effect of Temperature, Solvent Polarity, and Lewis Acid
作者:Priyadarsi De、Rudolf Faust、Holger Schimmel、Armin R. Ofial、Herbert Mayr
DOI:10.1021/ma0498262
日期:2004.6.1
electrophilicity parameter (E = 9.6) of the 1-phenylethyl cation, 1+, has been determined and combined with the nucleophilicity parameter (N = 0.78, s = 0.95) of styrene (St) to predict diffusion-limited propagation in the cationic polymerization of St by the linear free energy relationship log k = s(N + E). This prediction has been experimentally verified using two different diffusion clock methods, which
1-苯基乙基阳离子的亲电子参数(E = 9.6)1 +已确定,并与苯乙烯(St)的亲核参数(N = 0.78,s = 0.95)结合,通过线性自由能关系log k = s(N + E)。该预测已通过两种不同的扩散时钟方法进行了实验验证,它们提供了k p ± ≈2×10 9 L mol -1 s -1的值,比先前接受的值高了6个数量级,用于传播的绝对速率常数TiCl 4的-80°C下在甲基环己烷/氯甲烷60/40(v / v)中诱导St聚合。所述ķ p ±值的温度范围内保持不变-50至-80℃,这表明传播不具有焓屏障; 但是,它随着溶剂极性的增加而适度增加。路易斯酸的性质对k p ±影响很小,因为用TiCl 4或SnCl 4获得了相似的值。电离的表观速率常数, ,失活速率常数,ķ -我,和电离的表观平衡常数, 也已被确定为温度的函数。这随温度的 升高略有增加,k - i适度增加;因此, 总聚合速率随温度升高而适度降低。
Designed electron-deficient gold nanoparticles for a room-temperature C<sub>sp3</sub>–C<sub>sp3</sub> coupling reaction
作者:Qiu-Ying Yu、Hui Su、Guang-Yao Zhai、Shi-Nan Zhang、Lu-Han Sun、Jie-Sheng Chen、Xin-Hao Li
DOI:10.1039/d0cc06764d
日期:——
Room-temperature autocleavage of C–Br bonds via electron-deficient Au nanoparticles formed as a result of the rectifying contact with boron-doped carbons.
通过与硼掺杂碳的整流接触形成的电子亏损的金纳米颗粒,实现C–Br键的室温自解裂。
Cross-coupling reaction of secondary alkyl grignard reagents with allylic alcohols catalyzed by dichloro[1,1′-bis(diphenylphosphino)-ferrocene]palladium(II)
作者:Tamio Hayashi、Mitsuo Konishi、Makoto Kumada
DOI:10.1016/s0022-328x(00)93827-0
日期:1980.2
Dichloro[1,1′-bis(diphenylphosphino)ferrocene]palladium(II) was found to catalyze the reaction of allylic alcohols with 2-octylmagnesium chloride and 1-phenylethylmagnesium chloride to give the corresponding cross-coupling products in high yields.
Direct Coupling Reaction between Alcohols and Silyl Compounds: Enhancement of Lewis Acidity of Me<sub>3</sub>SiBr Using InCl<sub>3</sub>
作者:Takahiro Saito、Yoshihiro Nishimoto、Makoto Yasuda、Akio Baba
DOI:10.1021/jo061512k
日期:2006.10.1
The combination of InCl3 and Me3SiBr provided an enhanced Lewis acid system that can be used to promote a wide range of direct coupling reactions between alcohols and silyl nucleophiles in non-halogenated solvents, such as hexane or MeCN. The enhanced Lewis acidity of this system was measured by the C-13 NMR in terms of the coordination to an alcohol. Moreover, the interaction between Me3SiBr and the In(III) species was revealed by Si-29 NMR spectral analysis. Highly chemoselective allylations toward a hydroxyl moiety over ketone and acetoxy ones have been demonstrated.