Intramolecular-activation evidence for the unexpected Beckmann fragmentation of C(1)-substituted-7-bromonorbornane-2-ones

The competitive pathway timing for the previously described unexpected bromo-assisted Beckmann fragmentation of 7-anti-bromo-3,3-dimethyl-2-oxonorbornane-1-carboxamide has been investigated. It is concluded that this unusual process is activated by a synergic effect exerted by both the C(7)-anti-bromo and C(1)-aminocarbonyl groups. The effect consists in a specific intramolecular activation of the bromo-assistance by the bridgehead aminocarbonyl group.