An efficient synthesis of o-nitrophenyl tethered pyrazole-4-carbaldehydes was achieved via Vilsmeier-Haack formylation of hydrazone derivatives which were subjected to Claisen-Schmidt condensation and Morita-Baylis-Hillman (MBH) reaction with various methyl ketones and activated alkenes respectively to generate the corresponding chalcones and MBH adducts. However, successive Fe-mediated reductive cyclization was followed by an unusual C-C bond cleavage which afforded the pyrazolo[4,3-c]quinolines devoid of diverse substituents at C-4 position.

中文翻译：

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吡唑并[4,3-的合成

通过V衍生物的Vilsmeier-Haack甲酰化反应实现了邻硝基苯基束缚的吡唑-4-甲醛的有效合成，hydr衍生物经过Claisen-Schmidt缩合和Morita-Baylis-Hillman（MBH）反应，分别与各种甲基酮和活化的烯烃反应，得到生成相应的查耳酮和MBH加合物。然而，连续的铁介导的还原环化反应之后是不寻常的CC键断裂，从而提供了在C-4位置没有各种取代基的吡唑并[4,3- c ]喹啉。