Structure determination and conformation analysis of symmetrical dimers

Conformational and stereochemical analysis of six new symmetrical dimers was performed using proton–proton vicinal coupling measured from 1H NMR and 13C satellites of 1H NMR signals, natural abundance 13C‐edited nuclear overhauser effect (NOE) experiments, comprehensive NOE analysis and molecular modeling. The 13C satellite analysis and 13C‐edited NOE experiments were carried out to extract spectral information between equivalent protons. Molecular modeling was applied for estimations of three‐dimensional parameters of the studied dimers, which were subsequently used to generate a set of theoretical NOE for each possible conformation. The J‐coupling, 13C‐edited NOE and quantitative NOE analyses showed the predominance of gauche conformation for three dimers, whereas a mixture of gauche and anti conformations (45:55) for three other dimers was established by quantitative NOE analysis. X‐ray crystallographic study confirmed the stereochemistry of one of the dimers and revealed a discrepancy in conformation stability between liquid and solid states. Copyright © 2004 John Wiley & Sons, Ltd.