Rhodium-Catalyzed Stereoselective Amination of Thioethers with N-Mesyloxycarbamates: DMAP and Bis(DMAP)CH2Cl2 as Key Additives

A stereoselective Rh-catalyzed intermolecular amination of thioethers using a readily available chiral N-mesyloxycarbamate to produce sulfilimines in excellent yields and diastereomeric ratio is described. A catalytic mixture of 4-dimethylaminopyridine (DMAP) and bis-(DMAP) CH2Cl2 proved pivotal in achieving high selectivity. The X-ray crystal structure of the (DMAP)(2)center dot[Rh-2{(S)-nttl}(4)] complex was obtained and mechanistic studies suggested a Rh-II-Rh-III complex as the catalytically active species.