THE LITHIATION OF FLUORINATED BENZENES AND ITS DEPENDENCE ON SOLVENT AND TEMPERATURE
THE LITHIATION OF FLUORINATED BENZENES AND ITS DEPENDENCE ON SOLVENT AND TEMPERATURE
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DOI：
10.1039/p19950002729
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发表时间：
1995-11-07
期刊：
影响因子：
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通讯作者：
YARWOOD, TD
中科院分区：
文献类型：
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作者：
COE, PL;WARING, AJ;YARWOOD, TD
研究了氟化苯和氟化溴苯形成锂衍生物的过程。所用的碱是二异丙基氨基锂(LDA)的THF-己烷溶液、丁基锂的二乙醚-己烷溶液和丁基锂的THF-己烷溶液。锂化中间体已使用丙酮捕获，以形成氟化的2-芳基丙-2-醇，或已加热以产生苯炔，该苯炔已在狄尔斯-阿尔德加成中被呋喃捕获。 LDA的使用可以干净地去除芳环中最强的酸质子：乙醚-己烷中的丁基锂带来干净的溴-锂交换。相比之下，在- 78℃下在THF-己烷中使用丁基锂会导致自动金属化并形成更复杂的产物混合物。为了形成狄尔斯-阿尔德反应中涉及的苯炔，有必要加热反应混合物。当使用乙醚-己烷作为溶剂时，反应保持相当干净，但当添加THF时，增加的自金属化再次导致更复杂的反应混合物。
The formation of lithio derivatives from fluorinated benzenes and fluorinated bromobenzenes has been studied. The bases used were lithium diisopropylamide (LDA) in THF-hexane, butyllithium in diethyl ether-hexane and butyllithium in THF-hexane. The lithiated intermediates have been trapped using acetone, to form fluorinated 2-arylpropan-2-ols, or have been warmed to produce benzynes which have been trapped by furan in Diels-Alder additions. The use of LDA allows clean removal of the most acidic proton in the aromatic ring: butyllithium in ether-hexane brings about clean bromine-lithium exchange. In contrast, the use of butyllithium in THF-hexane at - 78 degrees C results in autometallation and the formation of more complex product mixtures, For the formation of the benzynes involved in the Diels-Alder reactions it is necessary to warm the reaction mixtures. When ether-hexane is used as solvent the reactions remain fairly clean, but when THF is added the increasing autometallation again results in more complex reaction mixtures.