title: Bridge-substituted calix[4]arenes: syntheses, conformations and application.
abstract: The bridge-substituted calix[4]arene carboxylic acid, 5,11,17,23-tetra-tert-butyl-25,26,27,28-tetramethoxy-calix[4]arene-2-carboxylic acid (1), can be readily converted to various esters 2-4 and reduced to the alcohol 5, which reacts with methyl iodide to give the ether 6. The alcohol can be dansylated to give 7, the fluorescence of which is selectively quenched by Cu(II) in acetonitrile. An attempt to convert the acid 1 to an amide resulted unexpectedly in the formation of a lactone 8. The conformational characteristics of 1-8 have been studied in solution and, in the cases of 2 and 4, in the solid state by determination of their single-crystal X-ray structures. With the exception of 8, in all these compounds the bridge substituent adopts an equatorial (lateral) orientation.
authors.affiliation: Institut für Organische Chemie, Technische Universität Bergakademie Freiberg, Leipziger Str. 29, D-09596, Freiberg/Sachsen, Germany.
authors.forename: Conrad
authors.initials: C
authors.lastname: Fischer
authors.forename: Tobias
authors.initials: T
authors.lastname: Gruber
authors.forename: Wilhelm
authors.initials: W
authors.lastname: Seichter
authors.forename: Edwin
authors.initials: E
authors.lastname: Weber
mesh_terms: D047250:Calixarenes / Q000138:chemical synthesis* / Q000737:chemistry*; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D008968:Molecular Conformation; D010636:Phenols / Q000138:chemical synthesis* / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D010636:Phenols; C121325:calix(4)arene; D047250:Calixarenes