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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
Author(s) -
Migda Wojciech,
Stankiewicz Anna,
Szneler Edward,
Ulman Lucyna,
Rys Barbara
Publication year - 2010
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.2657
Subject(s) - chemistry , undecane , bicyclic molecule , conformational isomerism , ring (chemistry) , ring flip , computational chemistry , stereochemistry , crystallography , molecule , organic chemistry
Temperature‐dependent 1 H and 13 C‐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.