Homolytic aromatic substitution of heterocyclic compounds. Part XIII. Arylation and heteroarylation of coumarin and benzo[<i>b</i>]furan using triazenes as the source of radicals. An experimental and theoretical study
作者:Gaston Vernin、Serge Coen、Jacques Metzger、Cyril Párkányi
DOI:10.1002/jhet.5570160120
日期:1979.1
In the case of benzo[b]furan, all the reactivity indices (F, Sr, and Ar) predict the position 2 to be most reactive, in agreement with the experimental results. Comparison of the mass spectra of the products indicates similarities between the spectra of arylcoumarins and arylbenzo[b]furans and the existence of a common intermediate in their fragmentation pattern, viz., the benzo[b]furan cation radical
均相芳基化(苯基中的取代基:无,对甲基,对氟,对氯,对溴,邻氯,2,4-二氯,3,5-二氯,2,3,4-研究了香豆素和苯并[ b ]呋喃的三氯,2,3,5-三氯,邻甲氧甲氧基,对甲乙氧基和邻苯基)和杂芳基化(2-噻唑基,2-苯并噻唑基,3-吡啶基)。通过在亚硝酸异戊酯的存在下将相应的1,3-二芳基三氮烯热分解生成自由基。香豆素的均质取代仅在位置3发生,与基于SCF-MO自由价的预测一致。在苯并[ b ]呋喃的情况下,所有反应指数(F,S r和A r)预测位置2最具有反应性,与实验结果一致。产物的质谱比较表明芳基香豆素和芳基苯并[ b ]呋喃的光谱之间相似,并且在其裂解模式中存在共同的中间体,即苯并[ b ]呋喃阳离子自由基。