4-(Trifluoromethyl)aniline → Leflunomide

Participants

Reaction Conditions

Reaction Steps

4-Trifluoromethylaniline (5.75 g, 35.7 mm) was dissolved in a mixture of NaHCO3 (3.16 g, 37.6 mm), N,N-dimethylacetamide (0.7 ml, 7.5 mm) and toluene (70 ml). The mixture was warmed to 40° C. and 5-methylisoxazole-4-carboxylic acid chloride (5 g, 34.4 mm) was added dropwise over 20 min. The mixture was stirred at this temperature for another 3 h. and then it was heated to reflux temperature. The hot mixture was washed with water (3×10 ml). The organic phase was allowed to cool to ambient temperature, which induced leflunomide to precipitate as a white powder. The powder was isolated by filtration and then dried at 60° C. to give leflunomide (8.0 g, 86%) in 99.5% purity.

Provenance & Evidence