Fritsch–Buttenberg–Wiechell rearrangement

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] The strong base deprotonates the vinylic hydrogen, which after alpha elimination forms a vinyl carbene.

The mechanism of the FBW rearrangement was a subject of on-surface studies where the vinyl radical was visualised with sub-atomic resolution.

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