Water → 1-(4-cyanophenyl)-5-(3,6-dimethyl-2,4-dioxo-1-(3-trifluoromethylphenyl)-1,2,3,4-tetrahydropyrimidin-5-yl)-1H-pyrazole-4-sulfonic acid

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Reaction Steps

To a suspension of the compound prepared in Example 1 (2.0 g) in acetonitrile (20 ml) was added concentrated sulfuric acid (1.08 ml) and the resulting mixture was stirred with heating under reflux for three hours. The reaction mixture was cooled to room temperature and thereto were added water (40 ml) and ethyl acetate (40 ml×1, 20 ml×1) such that the intended products were extracted into an organic layer. The organic layer was washed with saturated saline (20 ml), dried over anhydrous magnesium sulfate and then concentrated under reduced pressure. To the residue was added chloroform (10 ml) and the resulting mixture was stirred at 60° C. for thirty minutes. The mixture was stirred at room temperature overnight and the precipitated crystals were collected by filtration and washed with chloroform to afford 1-(4-cyanophenyl)-5-(3,6-dimethyl-2,4-dioxo-1-(3-trifluoromethylphenyl)-1,2,3,4-tetrahydropyrimidin-5-yl)-1H-pyrazole-4-sulfonic acid (2.06 g).

Provenance & Evidence