Internal asymmetric induction by the C-6 substituent on the oxidation reaction of interglycosidic sulfur atom of thiodisaccharides
Since the enantio or diastereoselective preparation of sulfoxides is a current challenge, we explore the possibility of inducing diastereoselectivity in the oxidation of the sulfur atom of thiodisaccharides, according to their substitution patterns. Thus, a series of 3-deoxy-4-S-(β-d-glucopyranosyl)...
| Autores: | , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 2017 |
| País: | Argentina |
| Institución: | Consejo Nacional de Investigaciones Científicas y Técnicas |
| Repositorio: | CONICET Digital (CONICET) |
| Idioma: | inglés |
| OAI Identifier: | oai:ri.conicet.gov.ar:11336/64338 |
| Acceso en línea: | http://hdl.handle.net/11336/64338 |
| Access Level: | acceso abierto |
| Palabra clave: | Sulfoxides Diastereoselectivity Thiodisaccarides oxidation https://purl.org/becyt/ford/1.4 https://purl.org/becyt/ford/1 |
| Sumario: | Since the enantio or diastereoselective preparation of sulfoxides is a current challenge, we explore the possibility of inducing diastereoselectivity in the oxidation of the sulfur atom of thiodisaccharides, according to their substitution patterns. Thus, a series of 3-deoxy-4-S-(β-d-glucopyranosyl)-4-thio-β-d-xylo-hexopyranoside derivatives, with different substituents at C-6 (OH, OAc or OTBS) of the reducing end, have been synthesized and treated with m-CPBA for the oxidation of the sulfur atom at C-4, which is vicinal to C-6. The absolute configuration at the sulfur stereocenter of the resulting sulfoxides was established taking into account shielding/deshielding anisotropic effects of the SO bond on the chemical shift of the NMR signals of selected protons, in the most populated syn φ/syn ψ conformation of the thiodisaccharide S-oxides. The OAc and OTBS derivatives afforded diastereomeric mixtures of R and S sulfoxides in a similar ratio (1.4 : 1 and 1.6 : 1, respectively). In contrast, the oxidation of thiodisaccharide with a free hydroxyl group at C-6 was completely diastereoselective in favor of the R sulfoxide. The influence of the thiodisaccharide C-6 substituent on the stereochemical course of the oxidation is discussed. |
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