Dibromination of alkenes with LiBr and H<sub>2</sub>O<sub>2</sub>under mild conditions
作者:Nayara Silva Martins、Eduardo E. Alberto
DOI:10.1039/c7nj04300g
日期:——
Electron-rich and electron-poor alkenes, and alkenes bearing protecting groups can be efficiently and stereoselectively converted to trans-dibromides using LiBr/H2O2 and AcOH as a proton source in 1,4-dioxane. For most substrates addition of 0.1 mol% of PhTeTePh enhances the reaction rate and the yield of the products. Experimental data suggest that the brominating agent prepared in situ is molecular
使用LiBr / H 2 O 2和AcOH作为1,4-二恶烷中的质子源,可以将富电子和电子贫乏的烯烃以及带有保护基的烯烃高效,立体选择性地转化为反式二溴化物。对于大多数底物,添加0.1 mol%的PhTeTePh可以提高反应速率和产物的收率。实验数据表明,原位制备的溴化剂是分子溴,LiBr有助于H 2 O 2的活化,从而在未经催化的实验中使用AcOH作为温和的质子源进行溴化反应。放大是可行的:在室温下一小时的反应中,将10.0 mmol的1-辛烯定量转化为1,2-二溴辛烯。