An Oxidative Macrobicyclic Ring Opening of a Triptycene to a Highly Functionalized Fluorene Derivative

The treatment of hexamethoxytriptycenes
with nitric acid leads
to an unprecedented oxidative ring opening of the triptycene scaffold,
resulting in a new class of fluorene derivatives with a nitroquinone
unit. Preliminary investigations of the influence of chain length
of alkyl substituents at the triptycene bridgeheads to the reaction
have been performed, revealing that exclusively the methyl-substituted
hexamethoxytriptycene does not undergo an oxidative ring opening reaction.