Conformationally Selective Synthesis of Mononitrocalix[4]arene in Cone or Partial Cone

Article abstract of DOI:10.1002/hlca.201600391

Nitro-substituted calixarenes in a cone and a partial cone conformation were prepared selectively using distinct synthetic routes. The selective nitration of tris- or penta-substituted phenols of calix[4]arene or calix[6]arene provided mononitrocalix[n]arenes (n?=?4, 6). Subsequent addition of ethylene glycol (EG) moieties to mononitrocalix[4]arene provided tetraEGylcalix[4]arene in locked partial cone conformation. By an alternative route – initial addition of EG moieties to the non-derivatized calix[4]arene followed by the uncontrolled nitration – provided mononitro- and dinitro-tetraEGylcalix[4]arenes locked in the cone conformation. These nitrocalix[4]arenes with locked cone or partial cone conformation are useful building blocks for further assembly of supramolecular systems, especially in the area of material sciences.