Steric and stereoelectronic effects in saturated heterocycles I. Small molecular fragment constituents. Theory vs. Experiment

Structural and energetic consequences of replacing one or more carbon atoms in small, cyclic and acyclic hydrocarbons with electronegative atoms or groups are reviewed. In this first part, the conformation-dependent steric and stereoelectronic effects on the properties (energies, structural parameters, etc.) of small molecular building blocks are scrutinized and these molecules are then used in a "fragment analysis" of larger molecules, such as carbohydrates or other mono-and polyheterocycles. Satisfactory results were obtained for molecules with single and multiple instances of anomeric and gauche effects involving O and N heteroatoms.