Rhodium-catalyzed stereoselective amination of thioethers with N-mesyloxycarbamates: DMAP and bis(DMAP)CH(2)Cl(2) 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)CH2 Cl2 proved pivotal in achieving high selectivity. The X-ray crystal structure of the (DMAP)2 ⋅[Rh2 {(S)-nttl}4 ] complex was obtained and mechanistic studies suggested a Rh(II) -Rh(III) complex as the catalytically active species.