Functionalization of the methylene bridges of the calix[6]arene scaffold

Katerina Kogan, Ishay Columbus*, Silvio E. Biali

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

33 Scopus citations


(Chemical Equation Presented) The bromine atoms of the hexabromo calixarene derivative 3 were replaced by other groups under SN1 conditions, allowing the facile synthesis of calix[6]arene derivatives incorporating identical functionalities at all bridges. Heating at reflux a mixture of 3 and the appropriate alcohol incorporated primary and secondary alkoxy substituents. Hydride abstraction was observed when the reaction with EtOH and i-PrOH was conducted in hexafluoroisopropanol (HFIP). Solvolysis of 3 in TFE in the presence of strong nucleophiles (such as N3- and aniline) afforded the corresponding hexaazido and hexaanilino derivatives. Hydroxyl groups were incorporated into the calix[6]arene scaffold via acetolysis of 3, followed by LiAlH4 reduction of the hexaacetate derivative obtained. Friedel-Crafts alkylations in the absence of Lewis acids were conducted by heating at reflux a mixture of 3, HFIP, and a substituted benzene derivative (e.g, m-xylene, p-methyl anisole, mesitylene). The calix[6]arene bridges were alkylated by heating at reflux a mixture of 3 and 2,4-pentanedione in TFE or HFIP. In all cases the reaction proceeded with high diastereoselectivity, and the major isomer isolated was assigned to the rc5 (i.e., all-cis) form. NMR spectroscopy indicates that the conformation adopted by the macrocycle possesses 3-fold symmetry (a "pinched cone") that is rigid in the laboratory time scale in the mesityl-substituted derivative.

Original languageAmerican English
Pages (from-to)7327-7335
Number of pages9
JournalJournal of Organic Chemistry
Issue number18
StatePublished - 19 Sep 2008


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