Synthesizing method of high-purity 3-methyl-N-[4-(trifluoromethyl) phenyl]-4-isoxazol formamide
A technology of dimethylaminomethylene acetoacetamide and trifluoromethyl, which is applied in the field of synthesis of isoxazole compounds to achieve the effects of increased regioselectivity, increased yield, and easier purification
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Embodiment 1
[0020] Example 1: N-[(4-trifluoromethyl)phenyl]-2-dimethylaminomethyleneacetoacetamide (III)
[0021] N-[(4-trifluoromethyl)phenyl]acetoacetamide (245 g, 1.0 mol) and N,N-dimethylformamide dimethyl acetal (149 g, 1.26 mol) were added to 600 mL of toluene , start stirring, and heat up to reflux until the raw material disappears. Under reflux, slowly mix in 100 mL of isopropanol, continue to stir for 15 minutes, cool down to 0-5°C, crystallize, filter with suction, and dry to obtain 225 g of an off-white solid with a yield of 75%.
Embodiment 2
[0022] Example 2: 3-methyl-N-[4-(trifluoromethyl)phenyl]-4-isoxazole carboxamide (I)
[0023] Add N-[(4-trifluoromethyl)phenyl]-2-dimethylaminomethyleneacetoacetamide (300g, 1.0mol) into 1000ml of methanol, start stirring, and cool the reaction system to -5 After ℃, slowly add 50% aqueous solution of hydroxylamine (66g, 1.0mol) dropwise, keep the stability of the reaction system at -5 ℃ ~ 0 ℃ during the dropwise addition, and add dilute hydrochloric acid dropwise to maintain the pH of the reaction solution at about 6.0 . After the dropwise addition, raise the temperature to 10°C to 15°C to continue the reaction, while maintaining the pH of the reaction solution at about 6.0 until the raw materials disappear. After the reaction was completed, the reaction solution (500ml×3) was extracted with ethyl acetate, and the organic phases were combined. The organic phase was washed once each with saturated aqueous sodium bicarbonate solution (400ml) and water (400ml), dried over anhyd...
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