Univerzita PardubiceFakulta chemicko- technologická

Univerzita Pardubice

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Publikace detail

A simple new method of the synthesis of methyl 1,4,5-trisubstituted-1H-pyrazole-3-carboxylates

Autoři: Brož Břetislav | Šimůnek Petr

Rok: 2012

Druh publikace: ostatní - přednáška nebo poster

Strana od-do: nestránkováno

Tituly:

Jazyk	Název	Abstrakt	Klíčová slova
eng	A simple new method of the synthesis of methyl 1,4,5-trisubstituted-1H-pyrazole-3-carboxylates	A new method for the synthesis of methyl 1,4,5-trisubstitued-1H-pyrazole-3-carboxylates which doesn’t involve using of hydrazines has been studied. This method can be carried out very simply and under mild conditions. Regarding the complex topic of the synthesis of persubstituted 1H-pyrazoles and the importance of pyrazole derivatives as pharmacophores and pesticides, this procedure could be a useful expansion of existing synthetic methods for the preparation of these substances. Several derivatives have been prepared by means of the basic-catalyzed reaction of 'push-pull"-polarized β-enaminoesters with benzenediazonium-tetrafluoroborates. The reaction mechanism has not been completely described yet, but it probably comprises a double azo-coupling with a subsequent intramolecular cyclization followed by releasing of nitrogen and the corresponding arene. The crucial effect of the basic catalyst has been determined: the reaction does not proceed without its presence and the right choice of the catalyst can affect the regioselectivity of the reaction. This work follows the recent studies on the synthesis of 3-acyl-4-amino-1-aryl-1H-pyrazoles [1–3]. The structures of the prepared products have been verified by means of GC/MS and NMR spectroscopy, some of them also by X-ray diffraction. The reaction conditions and procedures will be further discussed.	synthesis; 1,4,5-trisubstituted-1H-pyrazole-3-carboxylates