Artículos de revistas
Synthesis of chiral organotins suitable for the preparation of asymmetric heterogeneous catalysts
Fecha
2005-04Registro en:
Faraoni, María Belén; Ayala, Alicia D.; Vetere, Virginia; Casella, Mónica Laura; Ferretti, Osmar Alberto; et al.; Synthesis of chiral organotins suitable for the preparation of asymmetric heterogeneous catalysts; John Wiley & Sons Ltd; Applied Organometallic Chemistry; 19; 4; 4-2005; 465-472
0268-2605
CONICET Digital
CONICET
Autor
Faraoni, María Belén
Ayala, Alicia D.
Vetere, Virginia
Casella, Mónica Laura
Ferretti, Osmar Alberto
Podesté, Julio C.
Resumen
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.