Inside and outside N-bridged cavity systems: evidence for syn- and anti-atropisomers in scaffolds containing two N-benzoyl 7-azanorbornane units

Alkene and aziridine reagents containing N-benzoyl 7-azanorbornane componen ts have been prepared and used to construct [n]polynorbornanes in a block b uilding protocol. The presence of syn- and anti-atropisomers involving the restricted rotation of the N-COPh bridge was established by H-1 NMR spectro scopy in an NNN-[3]polynorbornane 4 (outside bridges) whereas the anti-conf ormer dominated in a cavity NCOCOCN-[7]isopolynorbornane 8 (inside bridges, X-ray confirmation) prepared by a dual 1,3-dipolar addition of an acute-an gled norbornene 6 with a hexacyclic bis-epoxide 7. (C) 2001 Published by El sevier Science Ltd.