Ni-Catalyzed hydrocyanation of alkenes with formamide as the cyano source
作者:Xiao Shu、Yuan-Yuan Jiang、Lei Kang、Luo Yang
DOI:10.1039/c9gc04275j
日期:——
“CN” generation from formamide dehydration! A novel Ni-catalyzed hydrocyanation of various alkenes to provide aliphatic nitriles is developed by generating hydrocyanic acid in situ from safe and readily available formamide. Excellent linear or branched regio-selectivity, wide substrate scope, cheap and stable nickel salt as a pre-catalyst, a safe cyano source, slow generation of “CN” to obviate catalyst
B(
<scp>
C
<sub>6</sub>
F
<sub>5</sub>
</scp>
)
<scp>
<sub>3</sub>
‐Catalyzed
</scp>
Hydroboration of Alkenes with
<scp>
<i>N</i>
‐Heterocyclic
</scp>
Carbene Boranes
<i>via</i>
B—H Bond Activation
作者:Qiaotian Wang、Wei Meng、Xiangqing Feng、Haifeng Du
DOI:10.1002/cjoc.202000489
日期:2021.4
Significantly, excellent regioselectivities were obtained in some cases. Mechanisticstudies indicate that the B—H bond cleavage is likely involved in the rate‐determining step. In addition, an electrophilic addition of NHC‐borenium cation to alkenes and the subsequent formation of carbocation are also postulated. The current work provides a promising method for the activation of stable borane adducts
在这项工作中,开发了一种新的活化N-杂环卡宾硼烷(NHC-硼烷)的方式,该方式是通过以沮丧的Lewis对方式通过路易斯酸B(C 6 F 5)3氢化物提取生成高反应性的两性离子物质。B(C 6 F 5)3的合适底物包括苯乙烯,β-甲基苯乙烯,苯乙烯和烷基烯烃等多种烯烃。催化硼氢化以高至高收率提供所需的产品。显着地,在某些情况下获得了优异的区域选择性。机理研究表明,在确定速率的步骤中可能涉及到B键的断裂。此外,还假定将NHC-硼阳离子亲电加成到烯烃中,并随后形成碳正离子。目前的工作为稳定硼烷加合物的活化提供了一种有前途的方法,这可能在将来引起一些有趣的转变。
Substituent Effect Studies of Aryl-Assisted Solvolyses. I. The Acetolysis of 2,2-Bis(substituted phenyl)ethyl<i>p</i>-Toluenesulfonates
The substituent effect on the acetolysis of 2,2-bis(substituted phenyl)ethyl p-toluenesulfonates at 90.10 °C can be described accurately in terms of the Yukawa–Tsuno (LArSR) relationship, giving a ρ value of −4.44 and an r value of 0.53. The substituent effect correlation of this system carrying two aryls is quite comparable to that of the 2-methyl-2-phenylpropyl system carrying a single aryl group, suggesting the close similarity in the structure of the transition states between the systems. The results can be reasonably accounted for on the basis of the accepted mechanism of this reaction, involving a rate-determining aryl-assisted transition state where only one aryl group of the two β-aryl groups participates.
The potential of a dicationic strontium ansa‐arene complex for Lewisacid catalysis has been explored. The key to its synthesis was a simple salt metathesis from SrI2 and 2 Ag[Al(ORF)4], giving the base‐free strontium‐perfluoroalkoxyaluminate Sr[Al(ORF)4]2 (ORF=OC(CF3)3). Addition of an ansa‐arene yielded the highly Lewisacidic, dicationic strontium ansa‐arene complex. In preliminary experiments,
双阳离子锶的电位安莎-arene复合物的路易斯酸催化已探索。合成的关键是从SrI 2和2 Ag [Al(OR F)4 ]进行简单的盐复分解,得到无碱锶-全氟烷氧基铝酸盐Sr [Al(OR F)4 ] 2(OR F = OC(CF 3)3)。一个的加成袢-arene,得到高度路易斯酸性,双阳离子锶袢-arene复杂。在初步实验中,该配合物已成功用作催化剂,可将CO 2还原为CH 4 和令人惊讶地控制的异丁烯聚合反应。