Synthesis of sulfonamides promoted by alkyl iodide via a hypervalent iodine intermediate

A new method for the preparation of sulfonamides from sodium sulfinates and amines is developed. A stoichiometric amount of m-chloroperbenzoic acid as oxidant and a catalytic amount of 1-iodopropane provides the corresponding sulfonamides in good yields under mild reaction conditions. In this protocol, 1-iodopropane is first oxidized by m-chloroperbenzoic acid into the corresponding hypervalent iodine intermediate iodosylpropane, which is highly unstable and decomposes at once to form hypoiodous acid. Then, the following reaction of the generated active hypoiodous acid with sodium sulfinates and amines results in the corresponding sulfonamides.