Facile synthesis of dihaloheterocycles via electrophilic iodocyclization

An efficient and facile electrophilic iodocyclization for the synthesis of various O-, N-, and S-containing dihaloheterocycles has been developed. A wide range of the substituted propargyl alcohols having -OH, -NTs, and -SAc functional groups reacted with molecular iodine or bromoiodine at ambient temperature to produce the corresponding dihalogenated O-, N-, and S-containing five- and six-membered heterocycles in good to high yields; Under optimized solvent conditions, the reactions of various substituted but-2-yn-1-ones bearing -OH, -NTs, and -SAc functional groups at C4-position, with iodine or bromoiodine at ambient temperature afforded the corresponding 3,4-diiodo- and 3-bromo-4-iodo-substituted furans, pyrroles, and thiophenes in good to high yields. Further transformation of the resulting iodine- or bromine-containing products to polyaromatics potentially of useful as organo-material intermediates has been investigated.