Dimethylbromosulfonium bromide reacted readily with many enones at 0° C or lower to precipitate a-bromo-β-sulfonium conjugated enones. These salts eliminate a proton and dimethylsulfide readily with aqueous potassium carbonate to give excellent yields of α- bromo conjugated enones cleanly. The mechanism of the addition was explained by the bromonium ion initiated 1, 4-addition followed by tautomerization of enol hypobromites.
[Groesbeek, M.; Galen, A. J. J. van; Ippel, J. H.; Berden, J. A.; Lugtenburg, J. Recueil des Travaux Chimiques des Pays-Bas, 1993 , vol. 112, # 4 p. 237 - 246]
