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NMR and computational study on the anomeric effect in cis / trans ‐3,4‐dihydro‐2‐alkoxy‐4‐substituted‐2 H ,5 H ‐pyrano[3,2‐ c ][1]benzopyran‐5‐one derivatives
Author(s) -
Annunziata Rita,
Raimondi Laura,
Nano Gian Mario,
Palmisano Giovanni,
Tagliapietra Silvia
Publication year - 1997
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(199711)35:11<721::aid-omr161>3.0.co;2-i
Subject(s) - chemistry , alkoxy group , diastereomer , conformational isomerism , substituent , stereochemistry , aryl , anomer , two dimensional nuclear magnetic resonance spectroscopy , anomeric effect , benzopyran , alkyl , molecule , organic chemistry
The configuration and conformation of cis / trans ‐3,4‐dihydro‐2‐alkoxy‐4‐(alkyl‐ or aryl‐substituted)‐2 H ,5 H ‐pyrano[3,2‐ c ][1]benzopyran‐5‐one derivatives were studied by combined NMR and computational analyses. The cis / trans configurational assignments of all diastereoisomers were achieved via 2D NOESY experiments. The conformational analysis of cis compounds, performed via NMR and computational studies, allowed the establishment of a preference for the conformer with both substituents in the pseudo‐equatorial orientations. For trans derivatives only the molecular mechanics analysis produced meaningful results, suggesting a general prevalence for the conformer bearing the 2‐alkoxy group in a pseudo‐axial and the 4‐substituent in a pseudo‐equatorial orientation. © 1997 John Wiley & Sons, Ltd.