Thermal transformation of cyclopropylazoarenes into the five-membered nitrogen-containing heterocycles

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• 作者：R. A. Novikov ; I. P. Klimenko ; E. V. Shulishov ; V. A. Korolev and Yu. V. Tomilov
• 关键词：cyclopropylazoarenes ; thermolysis ; N ; arylpyrazolines ; N ; arylpyrazoles ; naphtho[1 ; 2 ; d]oxazoles ; heterocyclization
• 刊名：Russian Chemical Bulletin
• 出版年：2008
• 出版时间：August, 2008
• 年：2008
• 卷：57
• 期：8
• 页码：1718-1724
• 全文大小：328.2 KB

文摘

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 ¡ãC 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.