Organocatalytic Asymmetric Michael Reactions of Cyclic <i>N</i>-Sulfonylimines with Nitroalkenes or 2-Nitroallylic Acetates

A highly efficient enantioselective Michael addition of cyclic <i>N</i>-sulfonylimines with nitroalkenes has been developed, utilizing a bifunctional squaramide catalyst. This approach achieves remarkable results, delivering products with high yields and outstanding stereoselectivities, reaching up to 97% yield, >20:1 dr, and >99% ee. Furthermore, an asymmetric tandem reaction of cyclic <i>N</i>-sulfonylimines with 2-nitroallylic acetates has been established. This innovative methodology involves a Michael/intramolecular aza-Michael cascade, leading to the formation of enantioenriched benzosultam-fused tricyclic compounds with excellent stereoselectivities (up to >20:1 dr and >99% ee).