corey-fuchs反应是指醛和cbr4及pph3反应,发生一碳同系化,生成二溴烯烃;接着用n-buli处理而得到末端炔烃。与早期的二溴烯烃衍生物的制备方法相比,zn粉的加入促进了叶立得中间体的生成,从而减少了ph3p的用量,分离更易,产率更高。对于敏感底物(如环氧醛),需用et3n代替zn才能取得好的效果。
反应机理
pph3亲核进攻cbr4,形成的中间体再被溴仿负离子亲核进攻,进而形成二溴亚甲基的磷叶立得。之后与wittig反应类似,与醛羰基加成形成的两性中间体环化成氧杂磷杂环丁烷,进一步碎裂为三苯氧磷和二溴烯烃。后者经n-buli发生反式hbr消除得溴炔,再和第二分子n-buli进行br-li交换,最后用酸淬灭便得增加一个碳得炔烃。
反应实例
参考文献
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87,1353-1364.
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6 gololobov,y. g.; nesmeyanov, a. n. tetrahedron 1987, 43, 2609-2651. (review).
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8 li, a.-h.; dai, l.-x.; aggarwal, v. k. chem. rev. 1997, 97, 2341-2372. (review).
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