Synthesis and cytotoxic evaluation of halogenated -exo-methylene-lactones

alpha-exo-Methylene-gamma-butyrolactones and alpha-exo-methylene-delta-valerolactones constitute an important group of natural and bioactive products. A simple and general protocol of halolactonization of dienoic acids to obtain various alpha-exo-methylene-lactones in excellent yields is described. The resulting halogenated alpha-exo-methylene-lactones were found to exhibit potent cytotoxic activities.