Calix[6]arene Functionalized at Four Bridges: Conformation and Intramolecular Guest Exchange

Avia Leader, Norbert Itzhak, Benny Bogoslavsky, Silvio E. Biali*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

Abstract

Reaction of the tert-butoxycarbonyl derivative of p-tert-butylcalix[6]arene (2) with excess NBS under irradiation yields a calixarene with four bromomethine bridges as the major product (3). On the basis of the number of signals in the NMR spectrum, to the product was assigned a 1,2,4,5-substitution pattern. X-ray crystallography indicates that the product possesses the rct2 configuration and crystallized as a mixture of two conformers. The major form in the crystal exists in a 1,2,3-alternate conformation where a single tert-butoxycarbonyl group is self-included in the cavity and all bromines are located at equatorial positions. A rotational barrier of 18.4 kcalmol-1 was measured for the intramolecular guest exchange rotational process that involves the mutual exchange between the unique self-included Boc group and the Boc group on the opposite ring (Boc = tert-butoxycarbonyl). Tetrabromocalix[6]arene 3 underoges an intramolecular guest exchange process involving the unique self-included Boc group and the Boc group on the oppiiosite ring (Boc = tert-butoxycarbonyl).

Original languageAmerican English
Pages (from-to)6489-6494
Number of pages6
JournalEuropean Journal of Organic Chemistry
Volume2015
Issue number29
DOIs
StatePublished - 1 Sep 2015

Bibliographical note

Publisher Copyright:
Copyright © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Keywords

  • Calixarenes
  • Cyclophanes
  • Halogenation
  • Host-guest systems
  • Macrocycles
  • Stereochemistry
  • Supramolecular chemistry

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