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.