Structure and conformation of heterocycles. 21. Probing the anomeric effect in orthoesters. Structure, conformation, and dynamic behavior of a unique orthooxalate: 2,5,7,10,11,14-hexaoxa[4.4.4]propellane

Geometrical parameters in the C(OC) 3 moiety of a series of orthoesters in X-ray diffraction structures were retrieved from the Cambridge Structural Database (CSD) and analyzed in the context of stereoelectronic effects. The seven independent conformers of trimethyl orthoformate were calculated both ab initio, using the 3-21G basis set, and with the MM2 force field suitably parametrized to include structural manifestations of the anomeric effect (MM2-AE)