反应详情

To a mixture of 3-phenyl-4-(trifluoromethyl)isoxazole-5-carboxylic acid (3.00 g, 11.7 mmol) and pyridine (1.132 mL, 14.0 mmol) in dichloromethane (100 mL) at room temperature was added 2,4,6-trifluoro-1,3,5-triazine (cyanuric fluoride) (1.18 mL, 14.0 mmol). The reaction mixture was stirred at room temperature overnight, diluted with dichloromethane (300 mL), washed with an ice-cold solution of 0.5N aqueous hydrochloric acid (2×100 mL), and the organic layer was collected. The aqueous layer was back-extracted with dichloromethane (200 mL), and the combined organic layers were dried anhydrous sodium sulfate and concentrated to afford 3-phenyl-4-(trifluoromethyl)isoxazole-5-carbonyl fluoride (2.91 g, 11.2 mmol, 96% yield) as a yellow, viscous oil. The product was found to react readily with methanol and on analysis was characterized as the methyl ester, which had an HPLC ret. time=2.56 min.-Column: CHROMOLITH® SpeedROD 4.6×50 mm (4 min.); Solvent A=10% MeOH, 90% H2O, 0.1% TFA; Solvent B=90% MeOH, 10% H2O, 0.1% TFA. LC/MS M+1=272.3 (methyl ester).

1. washwashed with an ice-cold solution of 0.5N aqueous hydrochloric acid (2×100 mL)
2. customthe organic layer was collected
3. extractionThe aqueous layer was back-extracted with dichloromethane (200 mL)
4. concentrationconcentrated