Anomeric effect electrostatic interpretation

The first interpretation of the conformational anomeric effect, given by Edward,2 invoked more favorable electrostatic interactions in the axial anomers than in the equatorial anomers of carbohydrates (Fig. 8). 

The rationalization of the conformational anomeric effect solely based on electrostatic interactions fails to account for these solvent effects. Another interpretation based on bond polarizability in 1,1-dialkoxyalkyl systems calls electronic transfer from a non bonding electron pair of one oxygen atom to the empty cr c 0 orbital from the other alkoxy substituent (Fig. 10).16... 

The electrostatic interpretation of the anomeric effect has generally been regarded as incomplete because it does not lead to quantitative agreement with experiment (188) and does not account for the observed geometries. In particular, dipole-dipole repulsive interactions have been criticized from the theoretical point of view on the basis of ab initio (189) and semiempirical EHMO and CNDO/2 calculations (190) and recently (191) based on the decreased barrier to ring inversion in 2,2-dimethoxyoxane (98, see Section... 

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