Thermal transformation of cyclopropylazoarenes into the five-membered nitrogen-containing heterocycles
作者:R. A. Novikov、I. P. Klimenko、E. V. Shulishov、V. A. Korolev、Yu. V. Tomilov
DOI:10.1007/s11172-008-0227-0
日期:2008.8
Cyclopropylazoarenes containing methoxy groups in the aromatic ring give the corresponding N-arylpyrazolines on the reflux in o-dichlorobenzene or on SnCl2 catalysis at 80 °C in good yields. The products can be smoothly oxidized into the corresponding pyrazoles. Thermolysis of cyclopropylazoarenes containing hydroxy groups in the aromatic ring proceeds more complicated. Thus in the case of resorcin azo derivative, strong resinification of the reaction mixture is observed and the corresponding N-arylpyrazoline is isolated only in −40% yield. Under similar conditions, thermolysis of 1-cyclopropyl- and 1-(1-methylcyclopropyl)azo-2-naphthol proceeds otherwise and unexpectedly leads to naphtho[1,2-d]oxazole derivatives with degradation of the cyclopropane ring.
芳香环中含有甲氧基基团的环丙基偶氮烯类化合物在邻二氯苯中回流或在 SnCl2 催化下于 80 °C 时生成相应的 N-芳基吡唑啉类化合物,收率良好。这些产物可以顺利地氧化成相应的吡唑。芳香环中含有羟基的环丙基偶氮烯烃的热分解过程较为复杂。因此,在间苯二酚偶氮衍生物的情况下,反应混合物会出现强烈的树脂化现象,相应的 N-芳基吡唑啉只能以-40%的产率分离出来。在类似的条件下,1-环丙基和 1-(1-甲基环丙基)偶氮-2-萘酚的热分解过程与此不同,意外地生成了环丙烷环降解的萘并[1,2-d]恶唑衍生物。