Fritsch-Buttenberg-Wiechell rearrangement
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The Fritsch-Buttenberg-Wiechell rearrangement, named for Paul Ernst Moritz Fritsch, Wilhelm Paul Buttenberg, and Heinrich G. Wiechell, is a chemical reaction whereby a 1,1-diaryl-2-bromo-alkene rearranges to a 1,2-diaryl-alkyne by reaction with a strong base such as an alkoxide.[1][2][3][4]
This rearrangement is also possible with alkyl substituents.[5]
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[edit] Reaction Mechanism
The strong base deprotonates the vinylic hydrogen, which after alpha-elimination forms a vinyl carbene. A 1,2-aryl migration forms the desired product, the 1,2-diaryl-alkyne.
[edit] Scope
One study explored this reaction for the synthesis of novel polyynes [6] [7]:
[edit] References
- ^ Fritsch, P.; Ann. 1894, 279, 319.
- ^ Buttenberg, W. P.; Ann. 1894, 279, 327.
- ^ Wiechell, H.; Ann. 1894, 279, 332.
- ^ Köbrich, G.; Angew. Chem. Int. Ed. 1965, 4, 49.
- ^ Rezaei, H.; Yamanoi, S.; Chemla, F.; Normant, J. F. Org. Lett. 2000, 2, 419-421.
- ^ One-Pot Formation and Derivatization of Di- and Triynes Based on the Fritsch-Buttenberg-Wiechell Rearrangement Thanh Luu, Yasuhiro Morisaki, Nina Cunningham, and Rik R. Tykwinski J. Org. Chem. 2007, 72, 9622-9629 doi:10.1021/jo701810g
- ^ The metal acetylide intermediate is captured by electrophile methyl iodide. The reaction product is a biomolecule found in for instance Bidens pilosa
