Synthesis of chiral organotins suitable for the preparation of asymmetric heterogeneous catalysts
A key step in the preparation of asymmetric heterogeneous catalysts based on silica-supported rhodium and platinum chemically modified with chiral organotins, is the synthesis of optically pure tin derivatives. We report on the synthetic pathways leading to the synthesis of (-)-menthyltin derivative...
| Autores: | , , , , , |
|---|---|
| Tipo de recurso: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 2005 |
| País: | Argentina |
| Institución: | Consejo Nacional de Investigaciones Científicas y Técnicas |
| Repositorio: | CONICET Digital (CONICET) |
| Idioma: | inglés |
| OAI Identifier: | oai:ri.conicet.gov.ar:11336/55201 |
| Acceso en línea: | http://hdl.handle.net/11336/55201 |
| Access Level: | acceso abierto |
| Palabra clave: | Chiral Ligand Heterogeneous Catalysts Hydrogenation Organotin Synthesis https://purl.org/becyt/ford/1.4 https://purl.org/becyt/ford/1 |
| Sumario: | A key step in the preparation of asymmetric heterogeneous catalysts based on silica-supported rhodium and platinum chemically modified with chiral organotins, is the synthesis of optically pure tin derivatives. We report on the synthetic pathways leading to the synthesis of (-)-menthyltin derivatives without the formation of epimerization by-products. The physical properties (including full 1H, 13C and 119Sn NMR spectra) of the new compounds, containing between one and three (-)-menthyl ligands attached to the tin atom, are reported. The preparation of two catalysts based on silica-supported rhodium and platinum chemically modified with (-)-menthyldiphenylmethyltin, as well as some studies on the catalytic hydrogenation of ethyl pyruvate, are also described. These studies show that the reductions lead to (R)- and (S)-ethyl lactates as the only products, that the (S) enantiomer was the isomer formed preferentially, and that the degree of conversion observed using both catalytic systems was almost quantitative (97-100%). The enantiomeric excesses observed were in the range 7-8%. One important advantage of these catalytic systems is their stability. Recycling of the used catalysts is possible, without any loss in the degree of conversion or enantiomeric excess. |
|---|