Cesium carbonate → 4-isopropyl-6-hydroxy-2-(1-phenyl-3-trifluoromethylpyrazol-5-yl-oxymethyl)-1,2-benzisothiazol-3(2H)-one 1,1-dioxide

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Reaction Conditions

Reaction Steps

A mixture 1-phenyl-3-trifluoromethyl-5-hydroxypyrazole (20.5 g; 89.92 mmol) and Cs2CO3 (17.6 g; 53.8 mmol) in methanol (50 ml) was stirred at 20° C. for 5 hours. The solvent was concentrated in vacuo, and the residue was dried in vacuo at 50° C. for 4 hours. To a solution of the above residue in 50 ml of DMF was added 2-bromomethyl-4-isopropyl-6-hydroxy-1,2-benzisothiazol-3(2H)-one 1,1-dioxide (25 g, 74.9 mmol) and the resulting mixture was stirred at room temperature (20° C.) overnight and poured into ether/brine. The above mixture was extracted with ether and the combined organic layer was dried over sodium sulfate, and concentrated in vacuo. The residue (46 g) was purified by column chromatography (silica gel; chloroform, 2% ethyl acetate in chloroform) and recrystallized from hexane to afford 25.7 g (71%) of 4-isopropyl-6-hydroxy-2-(1-phenyl-3-trifluoromethylpyrazol-5-yl-oxymethyl)-1,2-benzisothiazol-3(2H)-one 1,1-dioxide (Formula I: R1 =Ph; R2 =CF3 ; R3 =H; R4 =CH(CH3)2 ; R5 =6-OH) as a white solid.

Provenance & Evidence