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-alkenerearranges to a 1,2-diaryl-alkyne by reaction with a strong base such as an alkoxide.[1][2][3][4]
The Fritsch-Buttenberg-Wiechell rearrangement
This rearrangement is also possible with alkyl substituents.[5]
Reaction mechanism
The strong base deprotonates the vinylic hydrogen, which after alpha elimination forms a vinylcarbene. 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]
Mechanism of the Fritsch-Buttenberg-Wiechell rearrangement
Scope
One study explored this reaction for the synthesis of novel polyynes:[7][8]
^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
