Synthesis and Conformations of Adamantylated Calix[5]- and -[6]arenes

Procedures have been developed for the preparation of completely and partially adamantylated calixn]arenes (n = 5, 6) by reaction of 3-R-substituted 1-hydroxyadamantanes (R = H, 4-MeC₆H₄, 4-MeSO₂C₆H₄, 4-HO-3-HOCOC₆H₃, HOCOCH₂) with p-H-calixn]arenes (n = 5, 6) and 5,11,23,29-tetra-tert-butylcalix6]arene in trifluoroacetic acid. Lower- and upper-rim modification of the prepared compounds has been studied. According to the ¹H NMR data, adamantylcalix6]arenes possessing carboxymethyl groups in the adamantane moieties are characterized by reduced conformational mobility.