[NH2:1][C:2]1[N:6]([C:7]2[C:12]([CH3:13])=[CH:11][CH:10]=[CH:9][C:8]=2[CH3:14])[N:5]=[CH:4][C:3]=1[C:15]#[N:16].[OH:17]O.N>C(O)C.ClCCl>[NH2:1][C:2]1[N:6]([C:7]2[C:12]([CH3:13])=[CH:11][CH:10]=[CH:9][C:8]=2[CH3:14])[N:5]=[CH:4][C:3]=1[C:15]([NH2:16])=[O:17]2 g (9.4 mmol) of 5-amino-1-(2,6-dimethylphenyl)-1H-pyrazole-4-carbonitrile (Example 1A) are dissolved in 25 ml of ethanol, and a mixture of 20 ml of 30% strength hydrogen peroxide and 40 ml of 25% strength ammonia is added. The solution is stirred at room temperature overnight and then concentrated to about 15 ml in a rotary evaporator. The oily emulsion resulting thereby is taken up in dichloromethane. It is washed several times with water and saturated sodium thiosulphate solution. Drying over magnesium sulphate is followed by removal of the solvent in vacuo. The residue is purified by preparative HPLC (YMC Gel ODS-AQ S 5/15 μm; eluent A: water, eluent B: acetonitrile; gradient: 0 min 30% B, 5 min 30% B, 50 min 95% B). 0.88 g (40% of theory) of the product is obtained as colourless solid.
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