Conformational freezing of p-tert-butylcalix[6]arene in the cone structure by selective functionalization at the lower rim: synthesis of new preorganized ligands

The selective and symmetrical 1,3,5-methylation of p-tert-butylcalix[6] arene 1 is achieved for the first time; subsequent introduction of ester and amide binding groups on the trimethoxy-p-tert-butylcalix[6]arene 2 fixes the calix in the cone conformation giving new preorganized cation ligands.