Synthesis, NMR and DFT conformational studies of homooxacalixarene (cyanopropyl)oxy derivatives, precursors to urea-terminated compounds

Carla S. Proença, Paula M. Marcos, Filipa A. Teixeira, José R. Ascenso, Raul J. Bernardino, Peter Cragg

Research output: Contribution to journalArticle

Abstract

Direct O-alkylation of the parent compounds p-tert-butyldihomooxacalix[4]arene ( 1) and p-tertbutylhexahomotrioxacalix[ 3]arene (3) with 4-bromobutyronitrile and K2CO3 in acetonitrile afforded tetra- and tri-[(cyanopropyl)oxy] derivatives 2 and 4, respectively, as a mixture of conformers. These conformers were isolated and their conformational features studied by NMR spectroscopy (1H, 13C, COSY and NOESY) and DFT methods. Dihomooxacalix[4]arene tetra[(cyanobutyl)oxy] derivative 5 was also obtained and studied for comparison purposes. In general, good agreement was obtained between theoretical calculations and the NMR experimental data. For compounds 2 and 4 the partial cone conformation was the most stable, while the cone conformation was the most stable for derivative 5.
Original languageEnglish
Pages (from-to)7430-7437
Number of pages8
JournalTetrahedron
Volume69
Issue number35
Publication statusPublished - 2 Sep 2013

Keywords

  • Homooxacalixarenes
  • Synthesis
  • Cyano derivatives
  • Conformational analysis
  • NMR spectroscopy
  • DFT methods

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