Preparation method of isoxazole compound and isoxazole compound intermediate
A compound and isoxazole technology, applied in the field of organic synthesis, can solve the problems of dangerous post-processing process, many impurities and high cost, and achieve the effects of avoiding safety and three waste problems, high product purity and low cost
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[0035] A preparation method of isoxazole compounds, comprising the steps of:
[0036] Step A, in a solvent and in the presence of a base, compound (I) reacts with compound (II) at a certain temperature, and then continues to react with an oxidant to obtain an intermediate compound (III);
[0037] Step B, compound (III) reacts with an acid chloride reagent, and then reacts with alcohol at a certain temperature to obtain compound (IV), or reacts compound (III) with an alkylating agent at a certain temperature under the action of a base to obtain compound ( IV);
[0038] Step C, in a solvent, compound (IV) reacts with sulfide (V) at a certain temperature to obtain compound (VI);
[0039] Step D, in a solvent and in the presence of a base, compound (VI) and methyl ketone (VII) are condensed at a certain temperature to obtain compound (VIII);
[0040] Step E, in a solvent, after compound (VIII) and orthoformate (IX) and acid anhydride carry out ene etherification reaction at a ce...
Embodiment 1
[0060] Embodiment 1: the preparation of 4-chloro-3-nitrobenzotrifluoride
[0061] In a 1000mL three-necked flask, add 400g of p-chlorobenzotrifluoride, add a mixed acid of 273g of 98% sulfuric acid and 190g of 98% nitric acid dropwise at 30°C, continue to react for 4 hours after the dropwise addition, separate the organic layer, and wash the organic layer twice , to obtain 480g of 4-chloro-3-nitrobenzotrifluoride.
Embodiment 2
[0062] Embodiment 2: Preparation of 2-nitro-4-trifluoromethylbenzoic acid
[0063] In a 1000mL three-necked flask equipped with a thermometer, add 500g of DMF, 180g of potassium carbonate, and 78g of ethyl cyanoacetate. 150 g of 4-chloro-3-nitrobenzotrifluoride was added, and the temperature of the reactant was controlled within 50°C. After the dropwise addition, the reaction was continued to stir for 1 hour. Add 230g35%H dropwise 2 o 2 After the dropwise addition was completed, the reaction was continued for 2 hours, hydrogen peroxide was quenched, solvent removal was added, water was added, acidified with hydrochloric acid, filtered, washed with water, and dried to obtain 149g of 2-nitro-4-trifluoromethylbenzoic acid. 1 H-NMRδppm (DMSO-d 6 ): 14.39 (br, 1H), 8.46 (s, 1H), 8.21 (d, J=8.0Hz, 1H), 8.09 (d, J=8.0Hz, 1H).
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