一种合成3,5-二取代异噁唑的新方法  

New Synthetic Method for 3,5-Disubstituted Isoxazole

作　　者：朱敏[1] 金建昌[1] 童建颖[1] 李志英 

机构地区：[1]浙江树人大学生物与环境工程学院 [2]现代教育技术中心,杭州310015

出　　处：《高等学校化学学报》2013年第2期359-363,共5页Chemical Journal of Chinese Universities

基　　金：国家自然科学基金(批准号:21072176);浙江省自然科学基金(批准号:Y4100231)资助

摘　　要：研究了端基炔烃和醛肟在间氯过氧苯甲酸和催化量碘苯作用下的[3+2]环合反应,结果表明,该过程经过一个有机高价碘中间体而进行.通过该反应,端基炔烃在氧化剂间氯过氧苯甲酸和催化剂碘苯的作用下与醛肟反应,常温下可得到产率良好并具有区域选择性的3,5-二取代异噁唑化合物.本文考察了反应条件的影响,提出了可能的反应机理,为简便快速合成3,5-二取代异噁唑化合物提供了一种新方法.Isoxazoles are very important organic compounds,and many natural products and drugs contain the five-membered heterocycle moiety.A variety of synthetic methods has been known for preparation of iso-xazoles,of which the cycloaddition of nitrile oxides with alkynes is the most direct.In the reported procedures,the yields of isoxazoles are often quite low,side reactions result in impurities and both regioisomers are often obtained.Recently,the catalytic utilization of hypervalent iodine reagents is increasing in importance,with the growing interest in the development of environmentally benign synthetic transformations.In order to extend the scope of catalytic use of hypervalent iodine reagents in organic synthesis,we investigated the new method for preparation of isoxazoles using iodobenzene as catalyst and a novel catalytic method for synthesis of 3,5-disubstituted isoxazoles was reported.Terminal alkynes were mixed and stirred with oximes,m-chloroperbenzoic acid and a catalytic amount of iodobenzene in 2,2,2-trifluoroethanol at room temperature for several hours,a [3＋2] cycloaddition was easily be carried out,and after establishing optimal conditions,a series of 3,5-disubstituted isoxazoles was obtained in good yields.The possible mechanism for the cycloaddition was suggested,which included iodobenzene was first oxidized by m-chloroperbenzoic acid into the hypervalent iodine intermediate,then it transformed oximes to nitrile oxides in situ,following a cycloaddition of the nitrile oxides with alkynes to form isoxazoles.The method has some advantages such as mild reaction conditions,simple procedure and good yields.

关 键 词：异噁唑 有机高价碘中间体 催化氧化反应 [3+2]环合反应 

分 类 号：O621.3[理学—有机化学]