Enantioselective Synthesis of Cyclic Sulfamidates by Using Chiral Rhodium-Catalyzed Asymmetric Transfer Hydrogenation

Asymmetric transfer hydrogenation (ATH) of cyclic sulfamidate imines 4 and 9, using a HCO₂H/Et₃N mixture as the hydrogen source and well-defined chiral Rh catalysts (S,S)- or (R,R)-2, Cp*RhCl(TsDPEN), effectively produces the corresponding cyclic sulfamidates with excellent yields and enantioselectivities at room temperature within 0.5 h. ATH of 4,5-disubstituted imines 9, having preexisting stereogenic centers, is shown to take place with dynamic kinetic resolution.