Halogenation of Electron‐Deficient Vicinal Substituted Alkenes: Regio‐ and Stereoselectivity

The halogenation of electron‐deficient vicinal substituted alkenes leads mainly to the mixture of regio‐ and stereoisomers of monohalogenated derivatives. Their ratio depends on the stability of the intermediate anionic complex and is determined by properties of both electron‐withdrawing groups. Treatment with bromine solution converted electron‐deficient vicinal substituted alkenes into α‐ or β‐bromoenoates in different regio‐ and stereoselectivity. The formation of these polyfunctional isomeric esters is interpreted by DFT calculation methods.