赫克反应

赫克反应（Heck反应）也称沟吕木－赫克反应（Mizoroki－Heck反应），是不饱和卤代烃（或三氟甲磺酸酯）与烯烃在强碱和钯催化下生成取代烯烃的偶联反应。^[1]^[2] 它得名于美国化学家理查德·赫克和日本人沟吕木勉，赫克憑藉此貢獻得到了2010年諾貝爾化學獎。

原料卤代烃^[3] 或三氟甲磺酸酯中的R基可以是芳基、苄基或乙烯基。烯烃的双键碳必须连有氢，且烯烃通常为缺电子烯烃，如丙烯酸酯或丙烯腈。钯催化剂可以是四(三苯基膦)钯、氯化钯(II)或乙酸钯(II)。碱可以是三乙胺、碳酸钾或乙酸钠。

反应综述：^[4]^[5]^[6]

历史

在 Fujiwara （1967，藤原祐三）^[7] 和 Heck（1969年）^[8] 此前对芳烃与烯烃以及芳基卤化汞（ArHgCl）与烯烃在定量钯(II)催化反应的研究的基础上，1971年，日本化学家溝呂木报道了乙酸钾作碱和氯化钯催化下，碘苯与苯乙烯在甲醇中、120°C和加压的条件下偶联为二苯乙烯的反应。

1972年，Heck独立报道了碘代苯与苯乙烯的偶联反应，Heck小组采取无溶剂条件，并改用乙酸钯催化和有位阻的三正丁胺作碱。

（上述两个反应中的活性催化物种钯(0)都是由钯与烯烃配位而产生。）

1974年，Heck 向反应引入膦配体。^[9]

反应机理

Heck 反应的催化循环是围绕催化的钯中心而展开，如下图所示。循环中所需的活性钯(0)一般是由钯(II)前体在反应中原位产生，^[10] 例如，乙酸钯可被三苯基膦还原为双(三苯基膦)合钯(0) (1)，进入催化循环，同时三苯基膦则被氧化为三苯基氧膦。

循环中，首先是电子不饱和的含钯物种 (1)与卤代烃氧化加成，钯插入到卤-碳键中。然后，钯原子与烯烃作用产生π配合物 (3)，配位的烯烃再顺式插入到钯-碳键中，得 (4)。 (4) 经旋转（未画出）异构化为扭张力较小的反式异构体后，发生β-氢消除反应，获得另一个钯与烯烃配位的中间体 (5)。(5) 经解配，即得反应产物烯烃，同时还产生钯(II)物种 (6)，而 (6) 在碳酸钾作用下发生还原消除，又转化为 (1)，从而获得再生。可见，反应中用到的碳酸钾是计量的，但钯却是催化性的。

此类催化机理不仅限于乙烯基化合物，其他钯催化偶联反应中也可以见到大同小异的循环，例如Sonogashira偶联反应（一个底物为炔）、Suzuki偶联反应（烯烃被芳基硼酸替代）和Stille反应（烯烃被芳基锡烷替代）等。循环也可应用于其他10族元素，如Negishi偶联反应便是有机锌与芳卤在钯或镍催化下的偶联，也是采取类似的机理。不过，铂却不遵循这一催化循环，因铂-碳键能较高。

立体选择性

Heck 反应具立体选择性，多产生反式产物，主要原因是体积较大的有机基团与卤钯基，在旋转一步时尽量互相远离。

此反应工业上用于药物萘普生（下图，通过溴萘甲醚与乙烯反应）和防晒霜组分对甲氧基肉桂酸异辛酯的制取。^[11]

变体

离子液体

离子液体存在下，Heck 反应可在无膦配体的条件下进行。例如，将乙酸钯和离子液体 (bmim)PF₆ 负载在反相硅胶的内腔，^[12] 可使反应在水中进行，催化剂亦可循环使用。

Heck氧连芳基化

顺式加成产生的中间体中，钯上的取代基被羟基取代，最后产生具四氢呋喃环系的产物。^[13]

氨基-Heck反应

如：以三乙胺为碱，四(三苯基膦)钯催化，连有强吸电子基的肟可与末端双烯发生分子内偶联，形成具新 C-N 键的吡啶衍生物。^[14]

参见

参考资料

^ Heck, R. F.; Nolley, Jr., J. P. Palladium-catalyzed vinylic hydrogen substitution reactions with aryl, benzyl, and styryl halides. J. Org. Chem. 1972, 37(14): 2320–2322. doi:10.1021/jo00979a024.
^ Mizoroki, T.; Mori, K.; Ozaki, A. Arylation of Olefin with Aryl Iodide Catalyzed by Palladium. Bull. Chem. Soc. Jap. 1971, 44: 581. doi:10.1246/bcsj.44.581.
^ Littke, A. F.; Fu, G. C. (2005). "Heck reactions of aryl chlorides catalyzed by palladium/tri-tert-butylphosphine: (E)-2-Methyl-3-phenylacrylic acid butyl ester and (E)-4-(2-phenylethenyl)benzonitrile". Org. Synth. 81: 63.
^ Heck, R. F. Palladium-catalyzed vinylation of organic halides. Org. React. 1982, 27: 345–390. ISBN 978-0471264187. doi:10.1002/0471264180.or027.02.
^ A. de Meijere, F. E. Meyer, Jr.;. Fine Feathers Make Fine Birds: The Heck Reaction in Modern Garb. Angew. Chem. Int. Ed. Engl. 1994, 33: 2379–2411. doi:10.1002/anie.199423791.
^ Beletskaya, I. P.; Cheprakov, A. V. The Heck Reaction as a Sharpening Stone of Palladium Catalysis. Chem. Rev. 2000, 100: 3009–3066. doi:10.1021/cr9903048.
^ Motitani, Ichiro; Fujiwara, Yuzo. Aromatic substitution of styrene-palladium chloride complex. Tetrahedron Letters. 1967, 8: 1119. doi:10.1016/S0040-4039(00)90648-8.
^ Heck, Richard F. Mechanism of arylation and carbomethoxylation of olefins with organopalladium compounds. Journal of the American Chemical Society. 1969, 91: 6707. doi:10.1021/ja01052a029.
^ Dieck, H. A.; Heck, R. F. Organophosphinepalladium complexes as catalysts for vinylic hydrogen substitution reactions. Journal of the American Chemical Society. 1974, 96: 1133. doi:10.1021/ja00811a029.
^ Ozawa, F.; Kubo, A.; Hayashi, T. Generation of Tertiary Phosphine-Coordinated Pd(0) Species from Pd(OAc)2 in the Catalytic Heck Reaction. Chemistry Lett. 1992: 2177–2180. doi:10.1246/cl.1992.2177.
^ De Vries, Johannes G. The Heck reaction in the production of fine chemicals. Canadian Journal of Chemistry. 2001, 79: 1086. doi:10.1139/cjc-79-5-6-1086.
^ Hagiwara, Hisahiro; Sugawara, Yoshitaka; Hoshi, Takashi; Suzuki, Toshio. Sustainable Mizoroki–Heck reaction in water: remarkably high activity of Pd(OAc)₂ immobilized on reversed phase silica gel with the aid of an ionic liquid. Chemical Communications. 2005, (23): 2942–2944. PMID 15957033. doi:10.1039/b502528a.
^ Lorand Kiss, Tibor Kurtan, Sandor Antus, Henri Brunner. Further insight into the mechanism of Heck oxyarylation in the presence of chiral ligands (free fulltext). Arkivoc. 2003: GB–653J [2010-10-07]. （原始内容存档于2006-05-18）.
^ Mitsuru Kitamura, Daisuke Kudo, and Koichi Narasaka. Palladium(0)-catalyzed synthesis of pyridines from β-acetoxy-γ,δ-unsaturated ketone oximes (free fulltext). Arkivoc. 2005: JC–1563E.

延伸阅读

Beletskaya, I. P.; Cheprakov, A. V. The Heck Reaction as a Sharpening Stone of Palladium Catalysis. Chem. Rev. 2000, 100: 3009–3066. doi:10.1021/cr9903048.
Littke, A. F.; Fu, G. C. (2005). "Heck reactions of aryl chlorides catalyzed by palladium/tri-tert-butylphosphine: (E)-2-Methyl-3-phenylacrylic acid butyl ester and (E)-4-(2-phenylethenyl)benzonitrile". Org. Synth. 81: 63.

外部链接

Heck反应（页面存档备份，存于互联网档案馆）—organic-chemistry.org．
Heck反应（页面存档备份，存于互联网档案馆）—哈佛大学Myers讲义．
沟吕木－赫克反应（Mizoroki－Heck反应）（页面存档备份，存于互联网档案馆）

[1] Heck, R. F.; Nolley, Jr., J. P. Palladium-catalyzed vinylic hydrogen substitution reactions with aryl, benzyl, and styryl halides. J. Org. Chem. 1972, 37(14): 2320–2322. doi:10.1021/jo00979a024.

[2] Mizoroki, T.; Mori, K.; Ozaki, A. Arylation of Olefin with Aryl Iodide Catalyzed by Palladium. Bull. Chem. Soc. Jap. 1971, 44: 581. doi:10.1246/bcsj.44.581.

[3] Littke, A. F.; Fu, G. C. (2005). "Heck reactions of aryl chlorides catalyzed by palladium/tri-tert-butylphosphine: (E)-2-Methyl-3-phenylacrylic acid butyl ester and (E)-4-(2-phenylethenyl)benzonitrile". Org. Synth. 81: 63.

[4] Heck, R. F. Palladium-catalyzed vinylation of organic halides. Org. React. 1982, 27: 345–390. ISBN 978-0471264187. doi:10.1002/0471264180.or027.02.

[5] A. de Meijere, F. E. Meyer, Jr.;. Fine Feathers Make Fine Birds: The Heck Reaction in Modern Garb. Angew. Chem. Int. Ed. Engl. 1994, 33: 2379–2411. doi:10.1002/anie.199423791.

[6] Beletskaya, I. P.; Cheprakov, A. V. The Heck Reaction as a Sharpening Stone of Palladium Catalysis. Chem. Rev. 2000, 100: 3009–3066. doi:10.1021/cr9903048.

[7] Motitani, Ichiro; Fujiwara, Yuzo. Aromatic substitution of styrene-palladium chloride complex. Tetrahedron Letters. 1967, 8: 1119. doi:10.1016/S0040-4039(00)90648-8.

[8] Heck, Richard F. Mechanism of arylation and carbomethoxylation of olefins with organopalladium compounds. Journal of the American Chemical Society. 1969, 91: 6707. doi:10.1021/ja01052a029.

[9] Dieck, H. A.; Heck, R. F. Organophosphinepalladium complexes as catalysts for vinylic hydrogen substitution reactions. Journal of the American Chemical Society. 1974, 96: 1133. doi:10.1021/ja00811a029.

[10] Ozawa, F.; Kubo, A.; Hayashi, T. Generation of Tertiary Phosphine-Coordinated Pd(0) Species from Pd(OAc)2 in the Catalytic Heck Reaction. Chemistry Lett. 1992: 2177–2180. doi:10.1246/cl.1992.2177.

[11] De Vries, Johannes G. The Heck reaction in the production of fine chemicals. Canadian Journal of Chemistry. 2001, 79: 1086. doi:10.1139/cjc-79-5-6-1086.

[12] Hagiwara, Hisahiro; Sugawara, Yoshitaka; Hoshi, Takashi; Suzuki, Toshio. Sustainable Mizoroki–Heck reaction in water: remarkably high activity of Pd(OAc)₂ immobilized on reversed phase silica gel with the aid of an ionic liquid. Chemical Communications. 2005, (23): 2942–2944. PMID 15957033. doi:10.1039/b502528a.

[13] Lorand Kiss, Tibor Kurtan, Sandor Antus, Henri Brunner. Further insight into the mechanism of Heck oxyarylation in the presence of chiral ligands (free fulltext). Arkivoc. 2003: GB–653J [2010-10-07]. （原始内容存档于2006-05-18）.

[14] Mitsuru Kitamura, Daisuke Kudo, and Koichi Narasaka. Palladium(0)-catalyzed synthesis of pyridines from β-acetoxy-γ,δ-unsaturated ketone oximes (free fulltext). Arkivoc. 2005: JC–1563E.

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