Synthesis of N-aminopyrazoles by Fe(II)-catalyzed rearrangement of 4-hydrazonomethyl-substituted isoxazoles

Ekaterina E. Galenko, Viktor K. Ivanov, Mikhail S. Novikov, Andrey A. Zolotarev, Alexander F. Khlebnikov

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3 Citations (Scopus)

Abstract

A novel effective method is reported for the preparation of 1-amino-1H-pyrazole-4-carboxylic acid derivatives by Fe(II)-catalyzed rearrangement of isoxazoles having (2,4-dinitrophenylhydrazono)methyl substituent at C4. The reaction proceeds smoothly for both E and Z isomers of 4-(hydrazonomethyl)isoxazoles, and this means it is not necessary to separate mixtures of E/Z-isomers of the hydrazones prepared by reaction of 5-methoxy/pirrolidino-4-carbonylisoxazoles and 2,4-dinitrophenylhydrazine. The rearrangement proceeds via the formation of an aziridine intermediate which can be isolated in certain cases. The 2-nitro group in the synthesized 1-[(2,4-dinitrophenyl)amino]-1H-pyrazole-4-carboxylic esters can be selectively reduced in two steps via acylation of the amino group followed by hydrogenation-deacylation using H2-Pd/C.

Original languageEnglish
Pages (from-to) 6288-6298
Number of pages11
JournalTetrahedron
Volume74
Issue number43
DOIs
Publication statusPublished - 25 Oct 2018

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Scopus subject areas

  • Biochemistry
  • Drug Discovery
  • Organic Chemistry

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