= Solution
The <anomeric effect> is the preference, in suitable cyclic <acetals>, for an electronegative <substituent> at an anomeric <carbon> to occupy an axial position even when simple steric reasoning favours equatorial. An important orbital contribution is donation from an endocyclic <oxygen> <lone pair> into the <antibonding orbital> of the adjacent exocyclic C–O bond, $n_{\rm O}\to\sigma^*_{\rm C-O}$. The chair's axial arrangement supplies favourable antiperiplanar overlap. Electrostatic and <solvation> contributions can also affect the observed conformational preference.
Back to article page
