反应详情

56 ml of butyllithium (1.6 molar solution in n-hexane) are added dropwise, at -78° C., to 8 g of the tertbutylamide of 3-methylisoxazole-5-carboxylic acid in 150 ml of tetrahydrofuran. The mixture is stirred for 1 hour, after which 22 ml of dimethylformamide are slowly added dropwise. The mixture is allowed to reach room temperature overnight and is hydrolyzed with water, neutralized with concentrated hydrochloric acid and extracted with ether. The oil which remains after evaporation is chromatographed over silica gel sing cyclohexane/ethyl acetate. The tert-butylamide of 4-formyl-3-methylisoxazole-5-carboxylic acid is obtained as the first fraction, in the form of pale yellow crystals of melting point 36°-38° C. (compound No. 2).

1. waitto reach room temperature overnight
2. extractionextracted with ether
3. customafter evaporation
4. customis chromatographed over silica gel