Oxidation of gem-Borylsilylalkylcoppers to Acylsilanes with Air
摘要:
1-Boryl-1-silylalkylcoppers react with molecular oxygen in the presence of pyridine to afford acylsilanes efficiently. The one-pot process consists of two reactions: alkylation of 1-boryl-1-chloro-silylmethyllithium with Grignard reagents in the presence of copper(l) cyanide and aerobic oxidation of the alkylcopper species. This procedure enables us to access the divergent synthesis of acylsilanes.
研究了三氯乙酸钠与各种有机硅氢化物在1,2-二甲氧基乙烷中的反应,形成了α-三有机甲硅烷基二氯甲烷,产率为20%至50%。通过竞争反应确定在这些二氯卡宾的插入反应中这些氢硅烷的相对速率常数。一系列烷基取代的氢硅烷的相对反应性与硅上取代基的Taftσ*常数高度相关,ϱ *值为-1.07,一系列芳基取代的氢硅烷也显示出log k rel良好的线性相关性值具有Taftσ*常数,giving *值为-1.18。反应中的氢同位素效应k H / k D1.26±0.02。基于观察到的结果,可以得出结论,Cy 2插入SiH键中是通过三中心协同过程进行的,该过程中过渡态的电荷分离不大,正如塞弗特(Seyferth)对相关的PhHgCCl 2提出的那样。 Br / XC 6 H 4 SiMe 2 H反应。
The formation and alkylation of (trimethylsilyl)-, (phenyldimethylsilyl)-, and (diphenylmethylsilyl)dichloromethyllithium. Preparation of α,α-dichloroalkylsilanes and ((Z-1-chloro-1-alkenyl)silanes
作者:Gerald L. Larson、Osvaldo Rosario
DOI:10.1016/s0022-328x(00)91990-9
日期:1979.3
lithium reagents at −78°C is Ph2MeSiCCl2Li~PhMe2SiCCl2Li > > Me3SiCCl2Li. All three of the lithium reagents are readily silylated with chlorosilanes or alkylated with primary bromides and iodides. The α,α-dichloroalkylsilanes formed from the alkylation are stereoselectively dehydrochlorinated in refluxing dimethylformamide to ((Z)-1-chloro-alkenyl)silanes.
Tandem Insertion of Halocarbenoids and Lithium Acetylides into Zirconacycles: A Novel Rearrangement to Zirconium Alkenylidenates by β-Addition to an Alkynyl Zirconocene
作者:Jozef Stec、Emma Thomas、Sally Dixon、Richard J. Whitby
DOI:10.1002/chem.201002962
日期:2011.4.18
Tandem insertion of 1,1‐dihalo‐1‐lithio species (halocarbenoids) and lithium alkynides into zirconacyclopentenes and zirconcyclopentanes affords carbocyclic products in high yields via an unusual rearrangement that probably involves addition of an organolithium species to the β‐position of a zirconium–alkyne complex to give an alkenylidene–zirconate species. A wide variety of cyclopentanoid organic
Cleavage of α-halo-substituted alkyl groups from silicon. The mechanism of catalysis by ammonia buffer
作者:J. Chojnowski、W. Stańczyk
DOI:10.1016/s0022-328x(00)86286-5
日期:1975.10
from silicon in n-propanol—water in the presence of ammonia buffer. The separate rate constants for the concurrent base-catalysed and base-plus-nucleophile-catalysed processes have been determined for the compounds XC6H4(Me2)SiCHCl2 with X = H, p-MeO, p-Me, p-Cl, m-Cl, m-CF3 and a good correlation with σ-constants found for both types of catalysis. Solvent isotope effects and steric effects of substituents
Synthesis of carbocycles by insertion of 1,1-dihalo-1-lithio species into zirconacycles
作者:Nicolas Vicart、Richard J. Whitby
DOI:10.1039/a901722d
日期:——
1,1-Dihalo-1-lithio species (halogenocarbenoids) undergo double insertion into the carbon–zirconium bonds of a zirconacyclopent-ane or -ene to produce, after hydrolysis, bicyclo[3.3.0]oct-anes and -enes.