Abstract
A series of pyrazolo-fused 4-azafluorenones (indeno[1,2-b]pyrazolo[4,3-e]pyridines, IPP) were synthesized via the three-component reaction between arylaldehydes, 3-methyl-1H-pyrazol-5-amine and 1,3-indanedione in an ionic liquid as a catalyst at room temperature. The applied synthetic route has the advantages of easy work-up under mild reaction conditions presenting moderate yields and an environmentally benign procedure. A theoretical study based on conceptual-density functional theory has been done, bond reactivity indices have been calculated and an electrophilic and nucleophilic character of localized orbitals has been determined to analyze the possible electronic mechanisms.
Highlights
Were synthesized via the three-component reaction between arylaldehydes, 3-methyl-1H-pyrazol5-amine and 1,3-indanedione in an ionic liquid as a catalyst at room temperature
We describe a convenient regioselective synthesis of IPP in the absence of a metal catalyst
Motivated by the versatility and benefits offered by multicomponent reactions and with the purpose of creating efficient, versatile, and eco-friendly methodologies, we planned a facile three-component reaction for the construction of fused indeno[1,2-b]-pyrazolo[4,3-e]pyridines (IPP) heterocycles using an aminopyrazole (1), an aldehyde derivative (2), and indanedione (3)
Summary
Were synthesized via the three-component reaction between arylaldehydes, 3-methyl-1H-pyrazol5-amine and 1,3-indanedione in an ionic liquid as a catalyst at room temperature. 4-Azafluorenone (5H-indeno [1,2-b]pyridin-5-one) derivatives have aroused great interest in recent years due to their antimicrobial and antimalarial activities [1,2] These compounds are inhibitors of phosphodiesterase IV [3], participate in adenosine A2a receptor binding [4], are calcium antagonists [5], and have anti-inflammatory/anti-allergic properties [6]. They are used in the treatment of hyperlipoproteinemia and neurodegenerative diseases [4], and present anticancer activity [7]. 3-methyl-1-phenyl-1H-pyrazole-5-amine (1) has been the heterocyclic most intensively studied skeleton, 5-amino-pyrazoles are the most studied amines in this strategy
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