Pd-Catalyzed asymmetric [5 + 2] cycloaddition of vinylethylene carbonates and cyclic imines: access to N-fused 1,3-oxazepines

A Pd-catalyzed asymmetric [5 + 2] cycloaddition reaction was developed for the synthesis of N-fused 1,3-oxazepines using vinylethylene carbonates and sulfamate-derived cyclic imines. Under mild reaction conditions, a series of optically active N-fused 1,3-oxazepines were synthesized in good yields (up to 89%) and enantioselectivities (up to 90 : 10 er), indicating this method as a straightforward approach to enantiomerically enriched 1,3-oxazepine derivatives. The synthetic utility of the presented reaction was further demonstrated by the successful transformation of the resulting 1,3-oxazepines to useful polycyclic N-fused 1,3-oxazepanes.