Background: Pyrazolopyridines are interesting fused heterocyclic pharmacophores that combine pyrazole and pyridine; two privileged nuclei extensively studied and with a wide range of applications. They can be obtained by a broad variety of synthetic methods among which multicomponent reactions have gained importance, especially from 5-aminopyrazoles and dielectrophilic reagents. However, the search for new approaches more in tune with sustainable chemistry and the use of unconventional heating in three-component synthesis are open and highly relevant study fields. Methods: A novel, practical and efficient three-component synthesis of cycloalkane-fused pyra-zolo[4,3-e]pyridines was developed through a tandem reaction of 5-aminopyrazoles, cyclic ke-tones and electron-rich olefins, using microwave induction in perfluorinated solvent and iodine as catalyst. objective: To apply the principles of sustainable chemistry through a microwave-induced synthesis in perfluorinated solvent to obtain novel cycloalkane-fused pyrazolo[4,3-e]pyridines, taking advantage of the versatility of electron-rich olefins in iodine-catalyzed cascade heterocyclizations. Results: The microwave-induced three-component approach applied in this work promoted the construction of 10 new pyrazolopyridines with high speed and excellent control of regioselec-tivity, favoring the linear product with good yields; where the versatility of electron-rich olefins in iodine-catalyzed cascade heterocyclizations, granted the additional benefit of easy isolation and the possibility to reuse the fluorous phase. Conclusions: Although pyrazolopyridines have been synthetically explored because of their structural and biological properties, most of the reported synthetic methods use common or even toxic organic solvents and conventional heating or multi-step processes. In contrast, this study applied a multicomponent methodology in a single step by microwave induction and with the versatility provided in this case by the use of perfluorinated solvent, which allowed easy isolation of the final product and recovery of the fluorous phase.

中文翻译：

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5-氨基吡唑、环酮和富电子烯烃串联反应区域选择性合成环烷稠合吡唑并[4,3-e]吡啶

背景：吡唑并吡啶是一种有趣的稠合杂环药效团，结合了吡唑和吡啶；两个特权核心得到了广泛的研究和广泛的应用。它们可以通过多种合成方法获得，其中多组分反应变得重要，特别是从 5-氨基吡唑和亲电试剂。然而，寻找更符合可持续化学的新方法以及在三组分合成中使用非常规加热是开放且高度相关的研究领域。方法：利用微波，通过5-氨基吡唑、环酮和富电子烯烃的串联反应，开发出一种新颖、实用、高效的环烷烃稠合吡唑并[4,3-e]吡啶三组分合成方法。在全氟溶剂中以碘为催化剂进行感应。目标：利用富电子烯烃在碘催化级联杂环化中的多功能性，应用可持续化学原理，在全氟溶剂中通过微波诱导合成获得新型环烷烃稠合吡唑并[4,3-e]吡啶。结果：本工作中采用的微波诱导三组分方法促进了10种新型吡唑并吡啶的高速构建和良好的区域选择性控制，有利于线性产物的良好收率；其中富电子烯烃在碘催化级联杂环化中的多功能性赋予了易于分离和重新使用氟相的可能性的额外优点。结论：虽然吡唑并吡啶因其结构和生物学特性而被合成探索，但大多数报道的合成方法使用常见甚至有毒的有机溶剂和传统的加热或多步骤过程。相比之下，本研究通过微波感应一步应用了多组分方法，并通过使用全氟化溶剂提供了多功能性，从而可以轻松分离最终产物并回收氟相。