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.
Bibliographical noteFunding Information:
This work was supportedi n part by researchg rants from the Israel Science Foundation administeredb y the National Academy of Sciences and from the Ministry of Science and the Arts.