Sterically crowded cyclohexanes .9. Synthesis, conformation and dynamics of hexaspiro[2.0.4.0.2.0.4.0.2.0.4.0]tetracosane

The synthesis, conformation and dynamics of hexaspiro[2.0.4.0.2.0.4.0.2.0.4.O]tetracosane (3) are described. At room temperature in solution, 3 exists as 4:1 mixture of a rapidly interconverting twistboat conformation and a fixed chair conformation. The activation parameters for the chair-to-chair i...

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Bibliographic Details
Published inTetrahedron Vol. 53; no. 17; pp. 6011 - 6018
Main Authors Wulf, K, Klages, U, Rissom, B, Fitjer, L
Format Journal Article
LanguageEnglish
Published OXFORD Elsevier 28.04.1997
Subjects
Chemistry
Chemistry, Organic
Physical Sciences
Science & Technology
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Summary:The synthesis, conformation and dynamics of hexaspiro[2.0.4.0.2.0.4.0.2.0.4.O]tetracosane (3) are described. At room temperature in solution, 3 exists as 4:1 mixture of a rapidly interconverting twistboat conformation and a fixed chair conformation. The activation parameters for the chair-to-chair interconversion followed from a bandshape analysis of exchange broadened C-13 NMR spectra of [1,10,18-C-13]-3 as Delta H-# = 57.1 kJ/mol, Delta S-# = 35.4 J/mol.K, and Delta G(298)(#) = 67.6 kJ/mol. 3 is only the second case where a per(cyclo)alkylated cyclohexane populates a chair and a twistboat, and the first case where the twistboat predominates. (C) 1997 Elsevier Science Ltd.
ISSN:0040-4020
DOI:10.1016/S0040-4020(97)00289-5