反应详情

3.0 g of 2-methoxy-3-methylsulfinyl-4-trifluoromethylbenzoic acid and 1.02 g of 3-hydroxy-2-methylpyrazole are suspended in 20 ml of ethyl acetate and 5.07 ml of 3-methylpyridine under an inert atmosphere and cooled to −25° C. with stirring. 1.24 g of thionyl chloride are then slowly added dropwise such that the temperature always remains below −20° C. Following the complete addition of the thionyl chloride, the mixture is stirred for a further 20 minutes. 40 μl of cold water and 20 ml of methylcyclohexane are then added. The mixture is then stirred for a further 20 minutes at −25° C. The suspension is filtered and washed once with 10 ml of methylcyclohexane and twice with 10 ml of water in each case. Drying gives 3.67 g of (5-hydroxy-1-methyl-1H-pyrazol-4-yl)[2-methoxy-3-(methylsulfinyl)-4-(trifluoromethyl)phenyl]methanone (86.5% yield).

1. stirringthe mixture is stirred for a further 20 minutes
2. stirringThe mixture is then stirred for a further 20 minutes at −25° C
3. filtrationThe suspension is filtered
4. washwashed once with 10 ml of methylcyclohexane and twice with 10 ml of water in each case
5. customDrying