Abstract Reaction of chiral non racemic β-ketosulfoxides with amines or condensation of the imine enolates with (−)-methyl sulfinate yield optically pure β-iminosulfoxides. The second method requires the presence of an excess of MgBr 2 in order to avoid epimerization at sulfur. The highly diastereoselective reduction of these substrates can be successfully achieved only with DIBAL/ZnBr 2 (de 97%). Hydrogenolysis of the C S bond on the ...