SYNTHESIS OF DIARYLPYRAZOLES Russian patent published in 2008 - IPC C07D231/12 

FIELD: organic chemistry, chemical technology.

SUBSTANCE: invention relates to a method for synthesis of 3-halogenalkyl-1H-pyrazoles of the formula (I): wherein R₁ represents alkyl substituted with one or more halogen atoms; R₂ represents hydrogen atom, alkyl, cyano group, hydroxyalkyl, cycloalkyl or alkylsulfonyl; R₃ represents phenyl substituted with one or more alkyl, halogen atom; R₅ represents methyl, amino group, or its salts. Proposed method involves interaction of 1,3-diketone of the formula (II): or its salt with 4-sulfonylphenylhydrazine of the formula (III): or its salt in the reaction mixture comprising a solvent system wherein the reaction mixture if formed by combining the source of 1,3-diketone or its salt, the source of 4-sulfonylphenylhydrazine or its salt and a solvent system, and crystallization of a solid product of reaction comprising 1-(4-sulfonylphenyl)pyrazole or its salt from the reaction mixture. The source of 1,3-diketone or its salt or a mixture (mixtures) that can form by combination of 1,3-diketone source or its salt with a solvent system before its combining with source of 4-sulfonylphenylhydrazine comprises less 30 equivalents of water per equivalent of 1,3-diketone or its salt. 1-(4-sulfophenyl)pyrazole or its salt is at least 98 wt.-% of the synthesized solid reaction product. Also, invention relates to alternative method for synthesis of 3-halogenalkyl-1H-pyrazoles of the formula (I) showing the specific feature that involves using 4-sulfonylphenylhydrazine as a mineral acid salt that shows solubility in organic solvent at least 0.05 M at the reaction temperature. Except for, invention proposes a method for synthesis of 4-[5-(4-methylphenyl)-3-(trifluoromethyl)-1H-pyrazol-1-yl}benzenesulfonamide or 4-[5-(4-fluorophenyl)-3-(trifluoromethyl)-1H-pyrazol-1-yl]benzenesulfonamide. Invention provides realization of the method at high useful loading and synthesis of the end substances of high purity.

EFFECT: improved method of synthesis.

35 cl, 6 tbl, 11 ex