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NMR spectral analysis and molecular dynamics study of 3‐quinuclidinol and 3‐quinuclidinyl benzilate
Author(s) -
Heikkinen Sami,
Mesilaakso Markku,
Rahkamaa Erkki
Publication year - 1998
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/(sici)1097-458x(199809)36:9<627::aid-omr340>3.0.co;2-v
Subject(s) - chemistry , quinuclidine , coupling constant , chemical shift , molecular dynamics , proton , homonuclear molecule , computational chemistry , vicinal , torsion (gastropod) , proton nmr , nuclear magnetic resonance , stereochemistry , crystallography , molecule , organic chemistry , nuclear physics , physics , medicine , surgery , particle physics
Proton chemical shifts and coupling constants of 3‐quinuclidinol and 3‐quinuclidinyl benzilate were determined by computer analysis. The relatively broad lines of the quinuclidine protons have their origin in numerous non‐resolved transitions arising from the extensively coupled spin system of 12 nuclei. The signs of the long‐range coupling constants were determined by COSY‐45 and E.COSY. Vicinal coupling constants were converted into proton–proton torsion angles by applying the Altona–Haasnoot equation. Some geometrical ambiguities were revealed, which were studied by molecular dynamics calculations and simulated annealing. The torsion angles and the results from molecular dynamics calculations indicated significant flexibility of the quinuclidine part. For the sake of completeness the carbon chemical shifts of both compounds are presented. © John Wiley & Sons, Ltd.