Intramolecularly Bridged Calix[4]arenes with Pronounced Complexation Ability toward Neutral Compounds

Regioselective derivatization via
an organomercury intermediate
allowed for the introduction of carboxylic acid functionality into
the meta position of the calix[4]­arene skeleton.
Intramolecular Friedel–Crafts cyclization led to a novel type
of calixarene containing a ketone bridging moiety. Subsequent attack
of the ketone by organometallic compounds occurred selectively from
outside providing tertiary alcohols with the OH group oriented inside
the cavity. These compounds can complex neutral molecules both in
the solid state (X-ray) and in solution (NMR) using the cooperative
effect of hydrogen bonding (OH) and CH−π interactions
from within the cavity.