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The use of enaminones and enamines as effective synthons for MSA-catalyzed regioselective synthesis of 1,3,4-tri- and 1,3,4,5-tetrasubstituted pyrazoles

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Abstract

In the present work, an efficient regioselective synthesis of 1,3,4-tri- and 1,3,4,5-tetrasubstituted pyrazoles via a methanesulfonic acid (MSA)-catalyzed reaction of hydrazones with enaminones or enamines is reported. Mechanistically, the formation of the title compounds involves the [2+3] cycloaddition of hydrazones with enaminones or enamines followed by aromatization with acid and oxygen. This convenient method under mild conditions with various hydrazones, enaminones, and enamines was well-tolerated to afford products in good to excellent yields. Compared with the literature methods, this strategy has advantages such as materials that are available economically, metal-free catalysis, excellent regioselectivity, and high efficiency.

Graphical abstract: The use of enaminones and enamines as effective synthons for MSA-catalyzed regioselective synthesis of 1,3,4-tri- and 1,3,4,5-tetrasubstituted pyrazoles

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Publication details

The article was received on 16 Jul 2019, accepted on 29 Aug 2019 and first published on 29 Aug 2019


Article type: Paper
DOI: 10.1039/C9NJ03701B
New J. Chem., 2019, Advance Article

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    The use of enaminones and enamines as effective synthons for MSA-catalyzed regioselective synthesis of 1,3,4-tri- and 1,3,4,5-tetrasubstituted pyrazoles

    L. Duan, H. Zhou, Y. Gu, P. Gong and M. Qin, New J. Chem., 2019, Advance Article , DOI: 10.1039/C9NJ03701B

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