Process for preparing 5-methylisoxazole-4-carboxylic- (4'-trifluoromethyl)-anilide
申请人:——
公开号:US20030139606A1
公开(公告)日:2003-07-24
A process for preparing 5-methylisoxazole-4-carboxylic-(4′-trifluoromethyl)-anilide comprising: (a) reacting ethylacetoacetate, triethylorthoformate, and acetic anhydride at a temperature of from about 75° C. to about 150° C., to form ethyl ethoxymethyleneacetoacetic ester; (b) combining the ethyl ethoxymethyleneacetoacetic ester with sodium acetate or a salt of trifluoroacetic acid in the presence of hydroxylamine sulfate at a temperature of from about −20° C. to 10° C., to form ethyl-5-methylisoxazole-4-carboxylate; (c) reacting the ethyl-5-methylisoxazole-4-carboxylate with a strong acid to form 5-methylisoxazole-4-carboxylic acid; (d) reacting the crystallized 5-methylisoxazole-4-carboxylic acid with thionyl chloride to form 5-methylisoxazole-4-carbonyl chloride; and (e) reacting the 5-methylisoxazole-4-carbonyl chloride with trifluoromethyl aniline and an amine base at a temperature of from about 0° C. to about 50° C. to form 5-methylisoxazole-4-carboxylic-(4′-trifluoromethyl)-anilide. The process of the invention is especially advantageous for preparing 5-methylisoxazole-4-carboxylic-(4′-trifluoromethyl)-anilide, since the process: (1) eliminates or reduces the formation of the by-product 2-cyanoacetoacetic-1-(4′-trifluoromethyl)-anilide (CATA), generally as low as 0.0006%; (2) eliminates or reduces the formation of isomeric impurity ethyl-3-methyisoxazole-4-carboxylate and its corresponding acid as low as 0.1%, (3) produces a high quality of 5-methylisoxazole-4-carboxylic-(4′-trifluoromethyl)-anilide generally having 99.8-100% HPLC potency; and (4) does not require distillation of the isoxazole ester.
制备5-甲基异噁唑-4-羧酸-(4'-三氟甲基)-苯胺的过程包括:(a)在约75°C至约150°C的温度下,将乙酰乙酸乙酯、三乙基正甲酸酯和乙酸酐反应,形成乙酸乙酯亚甲基乙酮乙酸酯;(b)将乙酸乙酯亚甲基乙酮乙酸酯与乙酸钠或三氟乙酸盐在氢氧胺硫酸存在下,在约-20°C至10°C的温度下反应,形成乙酸-5-甲基异噁唑-4-羧酸酯;(c)将乙酸-5-甲基异噁唑-4-羧酸酯与强酸反应,形成5-甲基异噁唑-4-羧酸;(d)将结晶的5-甲基异噁唑-4-羧酸与氯化亚硫酸形成5-甲基异噁唑-4-羰基氯化物;(e)将5-甲基异噁唑-4-羰基氯化物与三氟甲基苯胺和胺碱在约0°C至约50°C的温度下反应,形成5-甲基异噁唑-4-羧酸-(4'-三氟甲基)-苯胺。该发明的过程特别有利于制备5-甲基异噁唑-4-羧酸-(4'-三氟甲基)-苯胺,因为该过程:(1)消除或减少了副产物2-氰基乙酮乙酸-1-(4'-三氟甲基)-苯胺(CATA)的生成,通常低至0.0006%;(2)消除或减少了异构杂质乙酸-3-甲基异噁唑-4-羧酸酯及其对应酸的生成至0.1%;(3)产生高品质的5-甲基异噁唑-4-羧酸-(4'-三氟甲基)-苯胺,通常具有99.8-100%的HPLC纯度;(4)不需要对异噁唑酯进行蒸馏。