Oxonium, trimethyl-, tetrafluoroborate(1-) (1:1) → 4-[5-(3,5-Dichloro-phenyl)-2,5-dimethyl-2,5-dihydro-isoxazol-3-yl]-2-methyl-benzamide

To a solution of 4-[5-(3,5-Dichloro-phenyl)-5-trifluoromethyl-4,5-dihydro-isoxazol-3-yl]-2-methyl-benzamide (200 mg) in 1,2-dichloroethane (3 ml) was added trimethyloxonium tetrafluoroborate (85 mg) and the reaction mixture was stirred at room temperature for 19 hours then more trimethyloxonium tetrafluoroborate (210 mg). After 4 hours 30 minutes, more trimethyloxonium tetrafluoroborate (0.5 ml) was added and after 2 hours, the reaction mixture was heated at (85° C.) for 18 hours. The solution was then concentrated under vacuo to give a crude residue (210 mg). Part of this residue (100 mg) of the crude was extracted between AcOEt and saturated NaHCO3. The organic phases were gathered, dried over anhydrous MgSO4, filtered and evaporated to give the desired compound (54 mg). 1H-NMR (CDCl3, δ in ppm): 7.50-7.31 (m, 6H), 5.75 (bs, 2H), 5.41 (s, 1H), 2.99 (s, 3H), 2.52 (s, 3H).