Unprecedented 1,3-Dipolar Cycloaddition: From 1,4,5,8-Naphthalene Bisimides to a New Heterocyclic Skeleton

1,4,5,8-Naphthalene bisimides react as dipolarophiles with in situ formed azomethine ylides. Double 1,3-dipolar cycloaddition is followed by unique ring rearrangement and leads to the formation of two six-membered rings. The formation of hexacyclic products is rationalized based on DFT calculations.