反应详情

To a solution of 3-phenyl-4-(trifluoromethyl)isoxazole-5-carboxylic acid (Intermediate I-3D, 0.500 g, 1.94 mmol) in dichloromethane (5 mL) and methanol (1 mL) at room temperature was added trimethyldiazomethane (2.0 M in ether) (1.26 mL, 2.53 mmol) slowly over 5 min. The resulting reaction mixture was stirred for 30 min. The reaction mixture was diluted with dichloromethane (40 mL) and washed with brine (20 mL). The aqueous layer was extracted with dichloromethane (2×20 mL), and the organic layers were combined and dried over anhydrous sodium sulfate. Concentration under reduced pressure afforded methyl 3-phenyl-4-(trifluoromethyl)isoxazole-5-carboxylate (0.513 g, 1.89 mmol, 97% yield) as a yellow oil. The product had an HPLC ret. time=2.55 min. (condition A); LC/MS M+1=272.0; 1H NMR (400 MHz, CDCl3) δ ppm 4.07 (s, 3H), 7.47-7.56 (m, 3H), and 7.59 (d, J=7.04 Hz, 2H).

1. customThe resulting reaction mixture
2. washwashed with brine (20 mL)
3. extractionThe aqueous layer was extracted with dichloromethane (2×20 mL)
4. dry with materialdried over anhydrous sodium sulfate
5. concentrationConcentration under reduced pressure