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A facile environment-friendly one-pot two-step regioselective synthetic strategy for 3,7-diarylpyrazolo[1,5-a]pyrimidines related to zaleplon and 3,6-diarylpyrazolo[1,5-a]pyrimidine-7-amines assisted by KHSO\(_{4}\) in aqueous media

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Abstract

3-Aminopyrazoles required for the synthesis of pyrazolo[1,5-a]pyrimidines were obtained by the reaction of enaminonitriles with hydrazine hydrate. The resulting aminopyrazoles are reacted with formylated acetophenones under reflux at \(60~ ^\circ \hbox {C}\) assisted by KHSO\(_{4}\) in aqueous media to form regioselectively 3,7-diarylpyrazolo[1,5-a]pyrimidines and 3,6-diarylpyrazolo[1,5-a]pyrimidine-7-amines. X-ray crystallography of selected compounds 5b and 7i further confirmed the regioselective formation of these products.

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Acknowledgments

Authors wish to thank Rev. Fr. Dr. Stephen Mavely, Vice Chancellor, Assam Don Bosco University for providing infrastructure for the execution of this work. Authors also wish to express their gratitude to IIT, Guwahati, Tezpur University, Tezpur, SAIF-NEHU, Shillong and SAIF-CDRI, Lucknow for providing spectral and analytical data. Our thanks are also due to the Department of Biotechnology (DBT), Government of India for a research project. SK thanks DBT-GOI for research fellowships.

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  1. Organic Research Lab., Department of Chemical Science, Assam Don Bosco University, Airport Road-Azara, Guwahati, Assam, 781017, India

    Asem Satyapati Devi, Shunan Kaping & Jai Narain Vishwakarma

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Devi, A.S., Kaping, S. & Vishwakarma, J.N. A facile environment-friendly one-pot two-step regioselective synthetic strategy for 3,7-diarylpyrazolo[1,5-a]pyrimidines related to zaleplon and 3,6-diarylpyrazolo[1,5-a]pyrimidine-7-amines assisted by KHSO\(_{4}\) in aqueous media. Mol Divers 19, 759–771 (2015). https://doi.org/10.1007/s11030-015-9606-2

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