Regioselectively controlled synthesis of 3(5)-(trifluoromethyl)pyrazolylbenzenesulfonamides and their effects on a pathological pain model in mice

• Regioselectively controlled synthesis of (1H-pyrazolyl)benzene-sulfonamides.
• Regioselective synthesis of (4,5-dihydropyrazol-1-yl)benzene-sulfonamides.
• Effect of dihydropyrazol-benzenesulfonamides on a pathological pain model in mice.
• Dihydropyrazol-benzenesulfonamides exhibited anti-hiperalgesic effect on mice.
• Dihydropyrazol-benzenesulfonamides are prototype analgesics to treat arthritis.

This study reports a facile and controllable synthetic method for the preparation of both 1,3- and 1,5-isomers of 4-(3(5)-aryl-3(5)-(trifluoromethyl)-1H-pyrazol-1-yl)benzenesulfonamides, as well as a new series of 4-(3-aryl-5-hydroxy-5-(trifluoromethyl)-4,5-dihydropyrazol-1-yl)benzenesulfonamides, from the cyclocondensation reaction of 4-aryl-1,1,1-trifluoro-4-methoxybut-3-en-2-ones or 1-aryl-4,4,4-trifluoro-butane-1,3-diones or their enolic forms with 4-hydrazinylbenzenesulfonamide. All compounds of the new series of 3-substituted 1-(4-benzenesulfonamide)-5-hydroxy-5-(trifluoromethyl)-4,5-dihydropyrazoles were tested for their effect on a pathological pain model in mice. The compounds 3a, 3b, 3c, 3e, and 3f presented anti-hyperalgesic action, while the compounds 3a, 3c, 3d, 3f, and 3g exhibited anti-edematogenic effects, without causing locomotive disorders in animals, thus making them comparable to Celecoxib in an arthritic pain model.

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