Imino-λ³-iodane and Catalytic Amount of I₂-Mediated Synthesis of N-Allylsulfenamides via [2,3]-Sigmatropic Rearrangement

A facile metal-free [2,3]-sigmatropic rearrangement reaction of allyl sulfides via N-sulfilimine intermediates has been developed. Treatment of allyl sulfides with imino-λ³-iodanes in the presence of a catalytic amount of elemental iodine allowed the reaction to proceed under mild conditions and gave the corresponding N-allylsulfenamide compounds in moderate to good yields. Several N-allylsulfenamide structures have been confirmed by single-crystal X-ray crystallography. The reaction initially involves the sulfonylimino group transfer reaction between imino-λ³-iodane and the sulfur atom, resulting in the formation of N-sulfilimine species, followed by [2,3]-sigmatropic rearrangement to form the N-allylsulfenamide.