反应详情

0.62 g of 4-[3-(3,5-Dichloro-phenyl)-4,4,4-trifluoro-but-2-enoyl]-2-methyl-benzoic acid ethyl ester (XVIIa) was mixed with 0.21 g of N-methylhydroxylamine hydrochloride and 0.42 ml of triethylamine in 10 ml of dry ethanol. The mixture was refluxed for 20 hours, evaporated to dryness and purified on silica gel giving 0.275 g (42%) of 4-[5-(3,5-Dichloro-phenyl)-2-methyl-5-trifluoromethyl-2,5-dihydro-isoxazol-3-yl]-2-methyl-benzoic acid ethyl ester (VIIIa) as a colorless oil 1H-NMR (CDCl3, δ in ppm): 7.93 (d, 1H), 7.30-7.45 (m, 5H), 5.43 (s, 1H), 4.37 (q, 2H), 2.99 (s, 3H), 2.61 (s, 3H), 1.40 (t, 3H).

1. temperatureThe mixture was refluxed for 20 hours
2. customevaporated to dryness
3. custompurified on silica gel giving 0.275 g (42%) of 4-[5-(3,5-Dichloro-phenyl)-2-methyl-5-trifluoromethyl-2,5-dihydro-isoxazol-3-yl]-2-methyl-benzoic acid ethyl ester (VIIIa) as a colorless oil 1H-NMR (CDCl3, δ in ppm): 7.93 (d, 1H), 7.30-7.45 (m, 5H), 5.43 (s, 1H), 4.37 (q, 2H), 2.99 (s, 3H), 2.61 (s, 3H), 1.40 (t, 3H)