Preparation of benziodazole-triflate and its application as both 2-iodobenzamido- and triflate-transfer reagents

Benziodazole-triflate, as a novel heterocyclic hypervalent iodine(III) reagent, was prepared from the reaction of hypervalent chloroiodine(III) with silver triflate under mild conditions. The structure of this new reagent was elucidated by NMR spectroscopy and X-ray crystallography, and its reactions with diverse α-electron withdrawing group substituted carbonyl compounds were investigated. The results implied that benziodazole-triflate could be selectively used as both a 2-iodobenzamido-transfer reagent for the synthesis of oxazole compounds, and a triflate-transfer reagent for the triflation of β-keto-sulfones. Ionic mechanistic pathways, supported by Density Functional Theory (DFT) calculations, were proposed to account for the divergent selectivities of the transformations.