Synthesis of pyrazolo[4,3-c]quinolines and the C-C bond cleavage during reductive cyclization
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Date
2021-02-26T00:00:00
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Publisher
Japan Institute of Heterocyclic Chemistry
Abstract
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. � 2021 The Japan Institute of Heterocyclic Chemistry.