Conformation of acetate derivatives of sugars and other cyclic alcohols. Crystal structures, NMR studies, and molecular mechanics calculations of acetates. When is the exocyclic CO bond eclipsed?.

A study of published crystal structures (of O-acetylated sugars for the most part) suggests that the exocyclic C−O bond in acetate esters of cyclic alcohols intrinsically prefers a staggered conformation, although the eclipsed conformation is only slightly less stable. When the acetate is flanked by...

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Bibliographic Details
Main Author: Nasser, Rima (author)
Other Authors: Gonzalez-Outeirino, Jorge (author), Anderson, J.Edgar (author)
Format: article
Published: 2005
Online Access:http://hdl.handle.net/10725/10380
http://dx.doi.org/10.1021/jo048295c
http://libraries.lau.edu.lb/research/laur/terms-of-use/articles.php
https://pubs.acs.org/doi/abs/10.1021/jo048295c
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Summary:A study of published crystal structures (of O-acetylated sugars for the most part) suggests that the exocyclic C−O bond in acetate esters of cyclic alcohols intrinsically prefers a staggered conformation, although the eclipsed conformation is only slightly less stable. When the acetate is flanked by two equatorial substituents the preferred conformation is close to eclipsed. Over 1500 C−OAc bonds have been analyzed. Diagnostic NMR criteria for torsion angles and MM3 calculations are reported and confirm these conclusions