Chemoselective oxidative hydrolysis of EWG protected α-arylamino vinyl bromides to α-arylamino-α′-bromoacetones

Vinyl bromides bearing an arylamino group in the vicinal position are chemoselectively transformed into interesting α-arylamino-α′- bromoacetones through a straightforward oxidative hydrolysis promoted by calcium hypobromite under mild acidic conditions. Significantly, this particular combination [vinyl bromides and Ca(BrO)2] avoids bromination at both the aromatic ring and activated positions in groups substituting the amine nitrogen. The usefulness of this class of brominated ketones has been shown in a Wittig homologation.