Catalytic asymmetric sulfimidation

A direct catalytic imidation of sulfides to sulfimides with [N-(p-tolylsulfonyl)imino]phenyliodinane (TsN=IPh) using a catalytic amount of copper triflate (CuOTf) has been developed. The reaction proceeds with a wide range of sulfides to give the corresponding sulfimides in 50-83% isolated yields. When the reaction is applied to allylic sulfides, the products are the corresponding sulfonamides produced via [2,3] sigmatropic rearrangement of the initially formed allylic sulfimides. In the presence of a chiral bis(oxazoline) as ligand, asymmetric induction occurs to afford the chiral sulfimides (up to 71% ee) and sulfonamides (up to 58% ee). Chloramine T (TsNClNa) can be used in place of TsN=IPh for asymmetric sulfimidation, but the ee's are much lower. Some mechanistic observations are described.