Position-addressable nano-scaffolds. I. The preparation of N,O-, N,C- and N,N-bridged sesquinorbornadiene succinimides as compact, highly functionalized addressable building blocks

Succinimide-functionalized N,O-,N,C-, and N,N- bridged benzol[2] polynorbornanes (benzosesquinorboradienes) are reported for the first time and are prepared by the cycloaddition of either five-membered cyclie 1,3-diennes onto N-subsisted benzo-7-azanorboradienomaleimides or N-subsituted isoindoles onto the appropriate norbornadienomaleimides. These products containan end-fused norbornen (or a 7-substituted relative) and have been designed to act as alkene BLOCKs for the production of nano-scaffold with up to six addressable sites supplied byeach norbornrnr unit. The N-bridges in these BLOCKs (and their coupled products) allow N-substituent mobilityby invertomerization of the sp3 nitrogen whereas the N-substituents on the succinimides are attached to an sp2 nitrogen atom and remain static. Preferred invertomer geometry can be determined using molecular modelling.