Stereoisomerization of β-Hydroxy-α-sulfenyl-γ-butyrolactones Controlled by Two Concomitant 1,4-Type Nonbonded Sulfur−Oxygen Interactions As Analyzed by X-ray Crystallography
| Autor: | Florenci V. González, Gabriel Peris, Santiago Rodríguez, José Antonio López Sáez, Amit K. Jain, Cristian Vicent |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2010 |
| Předmět: |
Models
Molecular Ketone Stereochemistry animal diseases Molecular Conformation chemistry.chemical_element Crystal structure Crystallography X-Ray symbols.namesake 4-Butyrolactone Molecule Van der Waals radius heterocyclic compounds chemistry.chemical_classification Organic Chemistry Stereoisomerism Sulfur nervous system diseases Oxygen Crystallography chemistry nervous system Cyclization Intramolecular force symbols health occupations Isomerization Lactone |
| Popis: | We have synthesized nine beta-hydroxy-alpha-sulfenyl-gamma-butyrolactones having different substituents. The syn-anti or syn-syn lactones (or any mixture of both) invariably isomerized into syn-anti/syn-syn lactones in a ratio of approximately 6/4. The other two possible isomeric lactones (anti-syn or anti-anti) were never observed. The crystal structures of syn-syn lactones have been determined. We found sulfur-oxygen distances to be less than the sum of the van der Waals radii (3.3 A), with the angle formed among the hydroxylic oxygen, sulfur, and quaternary aromatic carbon being close to 180 degrees. In addition, carbonylic oxygen-sulfur is directed40 degrees from the perpendicular to the C-S-C. Theoretical calculations were performed which emphasize the directionality of the sulfur-oxygen interaction. The X-ray and theoretical studies demonstrate that two concomitant, attractive 1,4 intramolecular interactions of divalent sulfur with both carbonyl and hydroxyl oxygens are the driving force for the aforementioned stereochemical preference. Then nonbonded sulfur-oxygen interactions would control the stereoselectivity of the reaction. The same features are observed in the X-ray structure of a beta-hydroxy-alpha-sulfinyl-gamma-butyrolactone. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|