The reaction of acetophenone hydrazones with TeCl4 in the presence of DBU gave a mixture of divinyl ditellurides and divinyl tellurides, which easily reacted with Cu powder in refluxing toluene to afford divinyl tellurides in good yields. The reaction of divinyl tellurides with bromine (1.2 eq.) gave the corresponding tellurium dibromide rather than the addition of the double bond whereas 3 molar amount
<i>N</i>-Bromosuccinimide and Lithium Bromide: An Efficient Combination for the Dibromination of Carbon-Carbon Unsaturated Bonds
作者:Min Shi、Li-Xiong Shao
DOI:10.1055/s-2006-941558
日期:——
Compounds possessing unsaturated bonds such as alkenes, alkynes, allenes, and methylenecyclopropanes (MCPs) can be dibrominated within minutes by NBS and lithium bromide in THF at room temperature in good to excellent yields under mild conditions.
FeBr3-catalyzed dibromination of alkenes and alkynes
作者:Yun Fa Zheng、Jian Yu、Guo Bing Yan、Xu Li、Song Luo
DOI:10.1016/j.cclet.2011.05.005
日期:2011.7
The dibromination of alkenes and alkynes with bromosuccinimide and sodium bromide catalyzed by FeBr3 under mild conditions has been developed. The trans-dibromo compounds were exclusively obtained with excellent yields.
Selective 1,2-dihalogenation and oxy-1,1-dihalogenation of alkynes by N-halosuccinimides
作者:Jinhua Liu、Wenjuan Li、Chao Wang、Yao Li、Zhiping Li
DOI:10.1016/j.tetlet.2011.06.047
日期:2011.8
1,2-Dihalogenation and oxy-1,1-dihalogenation of alkynes by N-halosuccinimides can be selectively realized through using different reaction conditions. alpha,beta-Dihalo alkenes were obtained exclusively using THF as solvent without using any catalyst, while alpha,alpha-dihalo ketones were synthesized using a mixed solvent of THF and H2O in the presence of FeCl3 center dot 6H(2)O. Terminal aromatic alkynes are smoothly transformed into alpha,alpha-dihalo ketones on water without a catalyst. (C) 2011 Elsevier Ltd. All rights reserved.