Reaction of (diacetoxyiodo)benzene with excess of trifluoromethanesulfonic acid. A convenient route to para-phenylene type hypervalent iodine oligomers

Reaction of (diacetoxyiodo)benzene [PhI(OAc)2] in trifluoromethanesulfonic acid (TfOH) resulted in oligomerization of PhI(OAc)2. Quenching with NaBr gave the bromide salts of hypervalent iodine oligomers that were determined by thermolysis with KI to be a para phenylene type of oligomers. Neutralization of the reaction mixture of PhI(OAc)2 and TfOH with aqueous NaHCO3 yielded the triflate salts of iodine oligomers. Furthermore, quenching the reaction mixture with aromatic substrates afforded arylated iodine oligomers. These iodine oligomers were found to be 3–4 of the number average degree of polymerization (Pn) by GC analysis of the thermolysis products and 1H NMR analysis. The major products, trimer and tetramer, were synthesized independently.