Comparative study of the vicinal functionalization of olefins with 2:1 bromide/bromate and iodide/iodate reagents

A comparative evaluation was made on the syntheses of vicinal halohydrins, halo methyl ethers, and halo acetates from olefins using 2:1 Br−/BrO3− and I−/IO3− reagents. In many cases both reagents afforded products selectively in high yields. The highest halogen atom efficiencies attained were 97% and 93% for Br−/BrO3− and I−/IO3−, respectively. Of the two reagents, I−/IO3− was established to be the preferred reagent for vicinal functionalization of linear alkenes and also for halo acetate preparation. However, only Br−/BrO3− was effective for vicinal functionalization of trans-stilbene and chalcones.