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Letters in Organic Chemistry

Editor-in-Chief

ISSN (Print): 1570-1786
ISSN (Online): 1875-6255

Four-Component Synthesis of pyrano[2,3-c]pyrazoles Catalyzed by Triphenylphosphine in Aqueous Medium

Author(s): Imene Amine Khodja, Amina Fisli, Oumeima Lebhour, Raouf Boulcina, Boudjemaa Boumoud and Abdelmadjid Debache

Volume 13, Issue 2, 2016

Page: [85 - 91] Pages: 7

DOI: 10.2174/1570178613666151203213214

Price: $65

Abstract

Background: The pyrano[2,3-c]pyrazoles have various biological properties such as antiinflammatory, anti-cancer, antifongical, analgesics and have a potential inhibitor for human ChK1 kinase. For these reasons several synthetic methods are reported. For our part we want to propose a method which respects the environment.

Method: To achieve our study we used as a model the condensation reaction of hydrazine hydrate, ethyl acetoacetate, benzaldehyde and malononitrile in the respective proportions of 1/1/1/1 and in the presence of Triphenylphosphine in various concentrations and different solvents.

Results: We found that the optimal conditions for this reaction are 10 mol% of catalyst in refluxed H2O. Given these results and to show the generality of the procedure, we applied the optimized reaction conditions for the synthesis of various dihydropyrano[2,3-c]pyrazoles from a range of substituted aromatic and heteroaromatic aldehydes. We have also applied these conditions by changing hydrazine by phenylhydrazine. The desired products are obtained in good to excellent yields.

Conclusion: We describe a simple, efficient and benign method for the dihydropyrano[2,3-c]pyrazoles synthesis by a four-component condensation between hydrazine (or phenylhydrazine), ethyl acetoacetate, malononitrile and a variety of aromatic and heteroaromatic aldehydes, catalyzed by Triphenylphosphine.

Keywords: Aqueous medium, multicomponent reaction, pyrano[2, 3-c]pyrazoles, triphenylphosphine.

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