3-取代苯基-5-羟基-5-三氟甲基异噁唑啉的合成

Synthesis of 3-(Substituted phenyl)-5-hydroxyl-5-trifluoromethyl-isoxazolines

3 取代苯基 5 羟基 5 三氟甲基异口恶唑啉是合成具有异口恶唑结构的原卟啉原氧化酶抑制剂类除草剂的重要中间体。通过以下途径制得4个具有不同取代基的异口恶唑啉中间体:首先,在回流状态,n(甲醇钠)∶n(取代苯乙酮)=2∶1的甲醇钠存在下,取代苯乙酮与三氟乙酸乙酯缩合得到取代苯基 4,4,4 三氟 1,3 丁二酮;后者可在室温下,于二氯甲烷溶剂中,用氯化硫酰氯化,在侧链上引入氯原子;最后,以乙酸作溶剂,回流下,具有不同取代基的苯基 1,3 丁二酮与盐酸羟胺闭环得到产物。反应总收率大于95%。产品结构经质谱、核磁共振氢谱、碳谱确认正确。

3-(Substituted phenyl)-5-hydroxyl-5-trifluoromethyl-isoxazolines are important intermediates of protox-inhibiting herbicides with isoxazole ring.Four isoxazoline intermediates with different substituted groups are obtained through the following steps.Firstly,substituted phenylethanone is treated with ethyl trifluoroacetate in the presence of sodium methoxide〔n(sodium methoxide)∶n(substituted phenylethanone)=2∶1〕 to get substituted phenyl-4,4,4-trifluoro-1,3-butandione,which,at room temperature in methylene dichoride,is chlorinated by treating with sulfonyl chloride to introduce chlorine atom to the side chain.Finally,in refluxing acetic acid,phenyl-4,4,4-trifluoro-1,3-butandiones with different substituted groups react with hydroxylamine hydrochloride to give the products with isoxazoline structure.The total yields of the title products are higher than 95%.Structures of the products are confirmed by MS,~1HNMR and^(13)CNMR.