Fritsch–Buttenberg–Wiechell rearrangement explained

The Fritsch–Buttenberg–Wiechell rearrangement, named for Paul Ernst Moritz Fritsch (1859–1913), 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]

Reaction mechanism

The strong base deprotonates the vinylic hydrogen, which after alpha elimination forms a vinyl carbene. A 1,2-aryl migration forms the 1,2-diaryl-alkyne product. The mechanism of the FBW rearrangement was a subject of on-surface studies where the vinyl radical was visualised with sub-atomic resolution.^[6]

Scope

One study explored this reaction for the synthesis of novel polyynes:^{[7] [8]}

See also

• Corey–Fuchs reaction

References

• Darses, B.; Milet, A.; Philouze, C.; Greene, A. E.; Poisson, J.-F. o., Ynol Ethers from Dichloroenol Ethers: Mechanistic Elucidation Through 35Cl Labeling. Organic Letters 2008, 10 (20), 4445-4447.

Notes and References

1. Ueber die Darstellung von Diphenylacetaldehyd und eine neue Synthese von Tolanderivaten. Paul Fritsch. . 279. 3 . 319–323. 1894. 10.1002/jlac.18942790310.
2. Condensation des Dichloracetals mit Phenol und Toluol . Buttenberg, W. P. . . 279 . 3 . 324–337 . 1894 . 10.1002/jlac.18942790311 .
3. Condensation des Dichloracetals mit Anisol und Phenetol . Wiechell, H. . . 279 . 3 . 337–344 . 1894 . 10.1002/jlac.18942790312.
4. Eliminations from Olefins . Köbrich, G. . . 4 . 49–68 . 1965 . 10.1002/anie.196500491.
5. Fritsch-Buttenberg-Wiechell Rearrangement in the Aliphatic Series . Rezaei, H. . Yamanoi, S. . Chemla, F. . Normant, J. F. . . 2 . 4 . 419–421 . 2000 . 10.1021/ol991117z . 10814340 .
6. Pavliček. Niko. Gawel. Przemyslaw. Kohn. Daniel R.. Majzik. Zsolt. Xiong. Yaoyao. Meyer. Gerhard. Anderson. Harry L.. Gross. Leo. 2018-07-02. Polyyne formation via skeletal rearrangement induced by atomic manipulation. Nature Chemistry. en. 10. 8. 853–858. 10.1038/s41557-018-0067-y. 1755-4330. 6071858. 29967394. 2018NatCh..10..853P.
7. 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
8. The metal acetylide intermediate is captured by electrophile methyl iodide. The reaction product is a biomolecule found in for instance Bidens pilosa