Enantioselective Synthesis of Diazobicyclic Oxadiazines via Organocatalytic [3+3]-Cycloaddition of gamma-Hydroxy-alpha,beta-Unsaturated Carbonyls with N, N '-Cyclic Azomethine Imines

A diastereo-and enantioselective synthesis of diazobicyclic oxadiazines was developed through an organocatalytic cycloaddition reaction. Asymmetric catalytic [3+3]-cycloaddition of gamma-hydroxy-alpha,beta-unsaturated carbonyls with N,N '-cyclic azomethine imines, using a squaramide-based catalyst, provided biologically important enantioenriched diazobicyclic oxadiazines in good yields with moderate to high di- astereo-and enantioselectivities (up to 10:1 dr and 79:21 er).