Fritsch-Buttenberg-Wiechell rearrangement

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.



This rearrangement is also possible with alkyl substituents.

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.