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A convenient one-pot synthesis of 1-aryl-substituted 4-iodopyrazol-3-ols via aromatisation and oxidative iodination reactions

Posted on 28. February, 2018.

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The pyrazolones, an important class of heterocyclic compounds, are prevalent in a wide range of bioactive compounds with pharmaceutical and agricultural activities. 4-Iodopyrazole-3-ols could open the way to a quick access to many pyrazolone analogues. However, iodination is usually difficult owing to the low electrophilicity of iodide.

In this paper, the authors report a facile one-pot, metal-free and iodine-atomeconomic synthetic protocol for the preparation of a series of new 4-iodopyrazole-3-ols from inexpensive and easily available pyrazolidin-3-ones using only 2 equiv. of H2O2, 1 equiv. of NaI and a catalytic amount of H2SO4.

A convenient and economical one-pot synthesis of a series of new 1-aryl-substituted 4-iodopyrazole-3-ols from easily available pyrazolidin3-ones in the presence of sodium iodide, 30% solution of hydrogen peroxide and a catalytic amount of sulfuric acid in dichloromethane via aromatisation and oxidative iodination reactions are described. This protocol has the advantages of high atom economy, cost effectiveness, short reaction time and environmental friendliness.

Read the full article in Journal of Chemical Research, Volume 42, Number 1, January 2018, pp. 24-27.


Authors: Jingjing Liu, Shanguang Yang, Ruimei Dong, Zhudan Jin and Mingliang Wang*
School of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189, P.R. China

Keywords: 4-iodopyrazol-3-ols, pyrazolidin-3-ones, aromatisation, oxidative iodination, hydrogen peroxide

Image: Proposed possible mechanism