(4-Methylphenyl)hydrazine → 4,5-dihydro-1-(4-methylphenyl]-5-(4-methylsulphonylphenyl)-3-trifluoromethyl-1H-pyrazole

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Reaction Steps

In a flask with an inert atmosphere (E)-1,1,1-trifluoro-4-(4-methylsulphonylphenyl)-3-butene-2-one (prepared according to the method E-1) (1.83 g, 6.58 mmoles) and 4-methylphenylhydrazine chlorohydrate (1.04 g, 6.58 mmoles) are dissolved in 50 ml de ethanol. A few drops of hydrochloric acid are added, and the mixture refluxed under an inert atmosphere for 4 days. The mixture is cooled and the product crystallised. The solution is filtered and the product recrystallised from ethanol. 4,5-dihydro-1-(4-methylphenyl]-5-(4-methylsulphonylphenyl)-3-trifluoromethyl-1H-pyrazole (0.8 g, yield: 32%) is obtained in the form of a solid with a melting point of 140-3° C.

Provenance & Evidence