Two record breakers for the anomeric effect; one real, the other not.

Abstract

The classic anomeric effect operates across a carbon atom attached to oxygens. One (of the two) lone pairs on the oxygen can donate into the σ* orbital of the C-O of the other oxygen ( <i> e.g. </i> the red arrows) tending to weaken that bond whilst strengthening the donor oxygen C-O bond. <em> Vice versa </em> means <em> e.g. </em> the blue arrows weakening the other C-O bond.