Selective Upper Rim Functionalization and Lower Rim Bridge Building with Calix[4]arenes and Calix[6]arenes1

Selective upper rim functionalization of calix[6]arenes has been achieved by selective lower rim benzoylation at the 1,2,4,5 positions followed by AlCl 3 -induced removal of the tert -butyl groups of the unesterified aryl residues and introduction of various functionalities into the vacated para positions, including bromo ( 5 ), dialkylamino, ( 7 − 11 ) cyanomethyl ( 12 ), and (propargyloxy)methyl ( 13 ) groups. Lower rim bridge building has been achieved via oxidative coupling reactions between the aryne moieties of calix[4]arenes and calix[6]arenes in which O -benzyl groups carry one (from 23 and 24 ) or two (from 25 ) propargyloxy residues. In the calix[4]arene series both a single-spanned ( 32 ) and a double-spanned ( 33 ) double-cavity calixarene were obtained. In the calix[6]arene series only a single-spanned double cavity calixarene ( 36 ) could be characterized.