Conformational studies of calix[5]arenes containing a single alkanediyl bridge

Silvio E. Biali, Volker Böhmer*, Ishay Columbus, George Ferguson, Cordula Grüttner, Flavio Grynszpan, Erich F. Paulus, Iris Thondorf

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


Six new calix[5]arenes substituted at one of the methylene bridges by methyl, ethyl, isopropyl, tert-butyl p-tolyl and p-nitrophenyl have been synthesised by heat induced (3+2) fragment condensation of a linear trimer with the corresponding bishydroxymethylated alkanediyl diphenols in boiling xylene. These conditions give the calix[5]arenes more reliably in about 20-30% yield, while the corresponding condensation with bisbromomethylated alkanediyl diphenols leads to complex mixtures from which sometimes only a calix[8]arene could be isolated. In agreement with molecular mechanics calculations the calix[5]arenes prefer the cone conformation with an equatorial position of the alkyl or aryl substituent at the bridge. From variable temperature 1H NMR spectroscopy the conformational equilibria and the energy barriers for the cone-to-cone ring inversion have been determined. Single crystal X-ray analyses have been performed for the calix[5]arene substituted by tert-butyl and for the corresponding tert-butyl substituted dinuclear precursor.

Original languageAmerican English
Pages (from-to)2261-2269
Number of pages9
JournalJournal of the Chemical Society. Perkin Transactions 2
Issue number10
StatePublished - Oct 1998


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