ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Theoretical stereochemistry of molecules with heteroatoms linked to the tetrahedral center and the anomeric effect

I. Tvaroška and T. Bleha

Institute of Chemistry, Centre for Chemical Research, Slovak Academy of Sciences, CS-842 38 Bratislava

Abstract: The review documents the progress accomplished during the last ten years in the understanding of the anomeric effect (an anomalous stabilization ot synclinal sc conformation). It is shown how the methods of theoretical chemistry assisted in the explanation of the anomeric effect in acetals, where it is of the primary importance, and in other acyclic molecules with heteroatoms of the type 0 or S linked to the tetrahedral centre. The paper summarizes for the model compounds the calculations of potential energies of individual conformers and their solvent dependence. The marked changes of valence geometry of molecules of this class at internal rotation are pointed out. The origin of the anomefic effect is explained as a consequence of electrostatic and delocalization interactions of lone electron pairs on heteroatoms. Finally, the attention is paid to the implication of results valid for small molecules to the prediction of conformational equilibrium in larger cyclic and polymeric analogues by means of the various semiempirical P dditive schemes.

Full paper in Portable Document Format: 396a805.pdf

Chemical Papers 39 (6) 805–847 (1985)