Oxygen p-type lone pair and adjacent

The Interaction between the Ring-Oxygen p-Type Lone Pair and Adjacent cr-Bonds in Pyranose Derivatives... 

Interaction between the Oxygen p-type Lone Pair and Adjacent q-bonds The interaction between the oxygen p-type lone pair and the adjacent antibonding orbital of a carbon-halogen bond was first considered in 1959 by Lucken as a possible explanation of the abnormally low NQR frequencies of Ot-haloethers (33). Later on, Altona showed that the same phenomenon could explain the peculiarities of some bond lengths in similar compounds (2). The spectroscopic properties of pyranose sugars which we have described in the first two sections of this article seem to imply that the existence of such an interaction lies beyond all possible doubt in these molecules. It does not follow that they can explain the Anomeric Effect (34) (35). For this, we need a quantitative estimation of the stabilization introduced in a molecule by such interactions. 

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