Controlling the regioselectivity of the bromolactonization reaction in HFIP.

The halolactonization reaction provides rapid access to densely functionalized lactones from unsaturated carboxylic acids. The / regioselectivity of this cyclization reaction is primarily determined by the electronic stabilization of alkene substituents, thus making it inherently dependent on substrate structures. Therefore this method often affords one type of halolactone regioisomer only.