title: Structural conditions required for the bridge lithiation and substitution of a basic calix[4]arene.
abstract: Lithiation and subsequent reaction with CO(2) was applied to calix[4]arenes with different, equal or mixed, ether functions at the lower-rim site as well as tert-butylated or non-tert-butylated upper-rim positions. Whereas this reaction fails for symmetric calix[4]arene ethers with alkoxy residues greater than methoxy, the carboxylation of mixed methoxy-propoxy calixarene ethers is possible. In connection with this, several new monobridge-substituted calix[4]arenes were characterized with respect to their conformational behaviour in solution and the X-ray crystal structure of one key intermediate is taken into consideration.
authors.affiliation: Institut für Organische Chemie, TU Bergakademie Freiberg, Leipziger Str. 29, 09596 Freiberg, Germany.
authors.forename: Conrad
authors.initials: C
authors.lastname: Fischer
authors.forename: Wilhelm
authors.initials: W
authors.lastname: Seichter
authors.forename: Edwin
authors.initials: E
authors.lastname: Weber