科里-富克斯反应

科里-富克斯反应，又称拉米雷斯-科里-富克斯反应，指醛与四溴化碳和三苯基膦反应，发生一碳同系化生成二溴烯烃，然后再用正丁基锂处理而得到末端炔烃。^[1]^[2]^[3]

反应由美国化学家艾里亚斯·詹姆斯·科里和菲利普·L·富克斯的名字命名。与早期Desai等^[4]制取二溴烯烃的方法相比，锌粉的加入促进了叶立德中间体的生成，从而减少了三苯基膦的用量，分离更易，产率更高。对于敏感的底物，需用三乙胺代替锌才能取得较好的效果。^[5]

选用适宜的碱，可使反应也可停在1-溴代炔一步。溴代炔和末端炔烃是有机合成中很有用的官能团。^[6]

近来工业界发展了三氯乙酸的等价合成方法，解决了大量合成中副产物三苯基氧膦的难处理问题，使反应用于大规模的制备。^[7]

反应机理

目前普遍接受的机理为，首先三苯基膦亲核进攻四溴化碳夺取一个溴离子，生成𬭸离子，它受到同时生成的溴仿负离子的亲核取代，形成二溴亚甲基磷叶立德。之后与维蒂希反应类似，二溴亚甲基碳与醛羰基进行亲核加成，形成的两性中间体环化为氧磷杂环丁烷，进一步消除为三苯基氧膦和二溴烯烃。

二溴烯烃与正丁基锂交换为锂代二溴烯烃，它发生β-消除生成溴代末炔。溴代末炔与正丁基锂再交换为末炔锂，末炔锂最后经水或卤代烃等亲电试剂处理，得末端炔或内炔。

参见

参考资料

^ Corey, E. J.; Fuchs, P. L. A synthetic method for formyl → ethynyl conversion (RCHO → RCCH or RCCR′). Tetrahedron Lett. 1972, 13 (36): 3769–3772. doi:10.1016/S0040-4039(01)94157-7.
^ Mori, M.; Tonogaki, K.; Kinoshita, A. "Synthesis of 1,3-Dienes from Alkynes and Ethylene: Acetic Acid 2-Methylene-3-phenethylbut-3-enyl Ester （页面存档备份，存于互联网档案馆）". Organic Syntheses, Vol. 81, p.1 (2005).
^ Marshall, J. A.; Yanik, M. M.; Adams, N. D.; Ellis, K. C.; Chobanian, H. R. "Generation of Nonracemic 2-(t-Butyldimethylsilyloxy)-3-butynyllithium from (S)-Ethyl Lactate （页面存档备份，存于互联网档案馆）". Organic Syntheses, Vol. 81, p.157 (2005).
^ N. B. Desai, N. McKelvie. A New Synthesis of 1,1-Dibromoölefins via Phosphine-Dibromomethylenes. the Reaction of Triphenylphosphine with Carbon Tetrabromide. J. Am. Chem. Soc. 1962, 84 (9): 1745–1747. doi:10.1021/ja00868a057.
^ D. Grandjean, P. Pale and J. Chuche. An improved procedure for aldehyde-to-alkyne homologation via 1,1-dibromoalkenes; synthesis of 1-bromoalkynes. Tetrahedron Letters. 1994, 35 (21): 3529–3530. doi:10.1016/S0040-4039(00)73227-8.
^ Craig M. Williams and Lewis N. Mander. Bridgehead Arylation: A Direct Route to Advanced Intermediates for the Synthesis of C-20 Diterpene Alkaloids. Org. Lett. 2003, 5 (19): 3499–3502. doi:10.1021/ol0353060.
^ Zhe Wang, Silvio Campagna, Kaihong Yang, Guoyou Xu, Michael E. Pierce, Joseph. M. Fortunak, and Pat. N. Confalone. A Practical Preparation of Terminal Alkynes from Aldehydes. J. Org. Chem. 2000, 65 (6): 1889–1891. doi:10.1021/jo9916582.

[1] Corey, E. J.; Fuchs, P. L. A synthetic method for formyl → ethynyl conversion (RCHO → RCCH or RCCR′). Tetrahedron Lett. 1972, 13 (36): 3769–3772. doi:10.1016/S0040-4039(01)94157-7.

[2] Mori, M.; Tonogaki, K.; Kinoshita, A. "Synthesis of 1,3-Dienes from Alkynes and Ethylene: Acetic Acid 2-Methylene-3-phenethylbut-3-enyl Ester （页面存档备份，存于互联网档案馆）". Organic Syntheses, Vol. 81, p.1 (2005).

[3] Marshall, J. A.; Yanik, M. M.; Adams, N. D.; Ellis, K. C.; Chobanian, H. R. "Generation of Nonracemic 2-(t-Butyldimethylsilyloxy)-3-butynyllithium from (S)-Ethyl Lactate （页面存档备份，存于互联网档案馆）". Organic Syntheses, Vol. 81, p.157 (2005).

[4] N. B. Desai, N. McKelvie. A New Synthesis of 1,1-Dibromoölefins via Phosphine-Dibromomethylenes. the Reaction of Triphenylphosphine with Carbon Tetrabromide. J. Am. Chem. Soc. 1962, 84 (9): 1745–1747. doi:10.1021/ja00868a057.

[5] D. Grandjean, P. Pale and J. Chuche. An improved procedure for aldehyde-to-alkyne homologation via 1,1-dibromoalkenes; synthesis of 1-bromoalkynes. Tetrahedron Letters. 1994, 35 (21): 3529–3530. doi:10.1016/S0040-4039(00)73227-8.

[6] Craig M. Williams and Lewis N. Mander. Bridgehead Arylation: A Direct Route to Advanced Intermediates for the Synthesis of C-20 Diterpene Alkaloids. Org. Lett. 2003, 5 (19): 3499–3502. doi:10.1021/ol0353060.

[7] Zhe Wang, Silvio Campagna, Kaihong Yang, Guoyou Xu, Michael E. Pierce, Joseph. M. Fortunak, and Pat. N. Confalone. A Practical Preparation of Terminal Alkynes from Aldehydes. J. Org. Chem. 2000, 65 (6): 1889–1891. doi:10.1021/jo9916582.

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