Iodonium salt 1 is a useful reagent for the construction of oxygen-containing heterocycles with concomitant introduction of an iodine atom. For example, the iodonium salt 1 electrophilically reacts with unsaturated alcohols and carboxylic acids to give cyclic ethers^1a) and lactones,^1b) respectively. In the analogous reactions with phenols or anilines, iodinated compounds can be obtained in high yield by a direct iodination.^1c)