Hunsdiecker-Borodin反应

学术   科学   2024-11-29 08:03   上海  

1939年,H. Hunsdiecker报道了干燥的脂肪羧酸银和溴反应可以得到少一个碳原子的溴代烷烃。脂肪羧酸,α,β-不饱和羧酸和特定的芳基甲酸进行脱羧卤代得到少一个碳原子的卤代烷烃的反应被称为Hunsdiecker反应

反应特点

一、羧酸银盐由羧酸和氧化银反应制备;二、羧酸银盐在在四氯化碳中剧烈搅拌,加入一倍当量的卤素,加入卤素的同时放出二氧化碳;三、为了得到较高的产率,银盐必须高纯度并且严格无水,但由于银盐热不稳定,因此得到干燥的银盐比较困难;四、脂肪羧酸反应最好,带有吸电子基团的芳香羧酸反应效果也不错;五、富电子的芳基羧酸在此反应条件下可以发生芳基亲电取代反应;六、除了银盐,更稳定的Tl(I)盐和Hg(I)盐也可以用于此反应;七、此反应条件下可以和卤素反应的基团(烯基,炔基)不兼容此反应;八、如果使用具有旋光活性的羧酸银,则产物烷基卤化物的旋光活性会明显降低。

反应改进

由于制备羧酸银盐有很高的技术难度,此反应有很多操作简便的改进法:一、如果在回流温度下将酰氯溶液加入干燥的氧化银/氯化四氯化碳/溴的悬浮液中,可以避免使用羧酸银盐,并且产率较高;二、易结晶的羧酸铊(I)盐用于此反应可以提高产率,缺点是铊盐毒性较高;三、Cristol-Firth改进法【Cristol-Firth脱羰卤代反应】利用过量的HgO和一个当量的卤素一锅饭反应操作简便;四、Suárez改进法,羧酸和高价碘试剂(乙酸碘苯)在CCl4中反应,可以明显改善官能团耐受度【J. Org. Chem. 1986, 51, 402-404】;五、Kochi改进法【Kochi脱羧氯代反应】,四乙酸铅和碘或卤化锂(LiCl或LiBr)可以直接得到卤代烷烃;六、Barton改进法,在卤素供体试剂(e.g., BrCCl3, CHI3) 存在下加热或光照分解硫代羟肟酸酯,此方法对大多数官能团耐受;七、如果AIBN用于Barton改进法,对于芳基羧酸(活化或非活化的)都可以高产率的脱羧



反应机理

自由基机理,银盐先和卤素反应得到一个不稳定的中间体(酰基次卤酸酯),然后脱羰得到卤代烃。此反应碳碳键发生均裂,按自由基机理进行。


反应实例

Org. Synth. 1988, Coll. Vol. 6, 179】



J. Org. Chem. 1990, 55, 4333-4337




1-Bromo-2-(p-methoxyphenyl)ethene (2). To LiOAc (0.2 mmol) in MeCN:H2O (97:3, 4.5 mL) was added p-methoxycinnamic acid 1 (336 mg, 2 mmol). After 5 min stirring at 20 ℃, NBS (365 mg, 2.1 mmol) was added as a solid. The mixture was stirred for 10 min. Workup and chromatography (silica gel, hexane:EA 3:2) afforded 386 mg of 2 (91%).

J. Org. Chem. 1997, 62, 199】


Tetrahedron Lett. 1998, 39, 699-702】


J. Am. Chem. Soc. 2000, 122, 5666-5667



Tetrahedron 2000, 56, 1369-1377】




 J. Org. Chem.200267, 7861-7864】




J. Org. Chem. 2004, 69, 8561-8563】




Synthesis2005, 1319-1325】




Tetrahedron Lett. 2007, 48, 4347-4351】



J. Am. Chem. Soc. 2012, 134, 4258-4263



相关文献

1. (a) Borodin, A. Ann. 1861, 119, 121-123. Aleksandr Porfirevič Borodin (1833-1887) was born in St Petersburg, the illegitimate son of a prince. He prepared methyl bromide from silver acetate in 1861, but another eighty years elapsed before Heinz and Cläre Hunsdiecker converted Borodin’s synthesis into a general method, the Hunsdiecker or Hunsdiecker-Borodin reaction. Borodin was also an accomplished

composer and is now best known for his musical masterpiece, opera Prince Igor. He kept a piano outside his laboratory. (b) Hunsdiecker, H.; Hunsdiecker, C. Ber. 1942, 75, 291-297. Cläre Hunsdiecker was born in 1903 and educated in Cologne. She developed the bromination of silver carboxylate alongside her husband, Heinz.

2. Sheldon, R. A.; Kochi, J. K. Org. React. 1972, 19, 326-421. (Review).

3. Barton, D. H. R.; Crich, D.; Motherwell, W. B. Tetrahedron Lett. 1983, 24,4979-4982.

4. Crich, D. In Comprehensive Organic Synthesis; Trost, B. M.; Steven, V. L., Eds.; Pergamon, 1991, Vol. 7, pp 723-734. (Review).

5. Lampman, G. M.; Aumiller, J. C. Org. Synth. 1988, Coll. Vol. 6, 179.

6. Naskar, D.; Chowdhury, S.; Roy, S. Tetrahedron Lett. 1998, 39, 699-702.

7. Das, J. P.; Roy, S. J. Org. Chem. 2002, 67, 7861-7864.

8. Ye, C.; Shreeve, J. M. J. Org. Chem. 2004, 69, 8561-8563.

9. Li, J. J. Hunsdiecker Reaction. In Name Reactions for Functional Group Transformations; Li, J. J., Corey, E. J., Eds., Wiley: Hoboken, NJ, 2007, pp 623-629. (Review).

10. Bazin, M.-A.; El Kihel, L.; Lancelot, J.-C.; Rault, S. Tetrahedron Lett. 2007, 48, 43474351.

11. Wang, Z.; Zhu, L.; Yin, F.; Su, Z.; Li, Z.; Li, C. J. Am. Chem. Soc. 2012, 134, 4258-4263.



参考文献

一、Strategic Applications of Named Reactions in OrganicSynthesis, László Kürti and Barbara Czakó, Hunsdiecker reaction,page 218-219.

二、Name Reactions (A Collection of Detailed Reaction Mechanisms), Jie Jack Li, Hunsdiecker-Borodin reaction,page 327-328.

三、organic chemitry portal:Hunsdiecker反应

四、Organic Syntheses Based On Name Reactions, 3RdEd, A. Hassner, Page 232.




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