5-(trifluoroMethyl)pyridine-2-sulfonaMide synthesis

Yield:332366-24-2 10%

Reaction Conditions:

Stage #1: 5-trifluoromethylpyridine-2(1H)-thionewith chlorine in water;acetic acid at 0; for 0.75 - 1 h;
Stage #2: with ammonium hydroxide in water;acetic acid at 0; for 0.166667 h;

Steps:

20 5-(Trifluoromethyl)pyridine-2-sulfonamide (117)

5-(Trifluoromethylpyridin-2(1H-thione (116), 10.0 g, 55.8 mmol) was placed in a flask containing 100 mL of water and 50 mL of acetic acid. The mixture was cooled to 0° C. and chlorine gas was bubbled into the mixture for 45-60 minutes. Water (100 mL) was added and a precipitate formed which was collected by filtration. This solid was cooled in an ice bath and in a separate flask 100 mL of cone. NH₄OH was also cooled in an ice bath. After 10 minutes, the cooled NH₄OH solution was added to the solid and the mixture was stirred overnight at room temperature. The mixture was then extracted with Et₂O (100 mL). The aqueous layer was collected and concentrated to give crude product that was purified by column chromatography on silica gel using EtOAc/hexanes gradients to afford 1.30 g of (117) (10%) as an off-white solid.

References:

US2008/21056,2008,A1 Location in patent:Page/Page column 93