Conformational analysis of cis‐3, 5‐dioxa‐bicyclo[5.4.0]undecane and its 4‐substituted derivatives by DNMR,molecular modeling,and GIAO/DFT methods |
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Authors: | Wojciech Migda Anna Stankiewicz Edward Szneler Lucyna Ulman Barbara Rys |
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Institution: | Department of Organic Chemistry, Jagiellonian University, Ingardena 3, 30‐060 Kraków, Poland |
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Abstract: | Temperature‐dependent 1H and 13C‐NMR spectra of the title compounds are presented. Coalescence effects are discussed and assigned to dynamic process—the interconversion of bicyclic system. The free energies of activation covered the range 39–52 kJ/mol. The dioxepane ring adopts twist‐chair (TC) conformation. GIAO/DFT calculation of isotropic shieldings for the set of low‐energy conformations showed that only one conformer is present at 298 K in solution that matched well with experimental data. Copyright © 2010 John Wiley & Sons, Ltd. |
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Keywords: | NMR 1H NMR 13C NMR DNMR 1 3‐dioxepane conformational analysis DFT GIAO |
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