"The steric interaction between any axial substituent and a β-situated heteroatom is counted as zero. Thus, in 3-substituted tetrahydropyrans, the destabilization due to an axial R substituent is computed as half of the AR. … The anomeric effect refers to the tendency of a group X at C(1) of a pyranose ring to assume the axial rather than the equatorial orientation. This phenomenon is important in carbohydrate chemistry since it influences the composition of isomeric mixtures and hence their reactivities. … The anomeric effect is solvent and substituent dependent …"
January 1, 1970
https://en.wikiquote.org/wiki/Heterocyclic_compound