A new method for the synthesis of 4-amino-3,5-dimethylpyrazoles and related compounds

Abstract

Previously synthesized azopyrazoles were reduced with hydrazine hydrate without a catalyst. This reaction is an attractive alternate for the reduction of the azo functional group to obtain a new primary amine. In this study, we used a new modified method for the synthesis of some 4-aminopyrazole derivatives. 4-amino-3,5-dimethylpyrazole (I), 4-amino-3,5-dimethyl-1-phenylpyrazole (II) 4-amino-3,5-dimethyl-1-(2-hydroxyethyl)pyrazole (III) and 4-amino- 1,3,5-trimethylpyrazole (V) were obtained with high yield. 4-amino-1-(2-acetyloxy)ethyl-3,5-dimethylpyrazole (IV) and its intermediate azo compound, 4-(4-ethoxycarbonylphenylazo)-3,5-dimethyl-1-(2-acetyloxyethyl)pyrazole (B), were synthesized as original compounds and their structures were elucidated using UV, IR, 1H-NMR and mass spectroscopic methods. The mentioned method is more cheaper and provides higher yield than our previous method for the synthesis of 4-aminopyrazole derivatives.