Tetrathiaheterohelicene Phosphanes as Helical-Shaped Chiral Ligands for Catalysis
| Autor: | Marco Monteforte, Alessandra Forni, Antonio Tiripicchio, Laura Raimondi, Tiziana Benincori, Stefano Maiorana, Emanuela Licandro, Silvia Cauteruccio, G. Richard Stephenson, Claudia Graiff |
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| Rok vydání: | 2011 |
| Předmět: |
Thiaheliphos
Ligand Stereochemistry Organic Chemistry Asymmetric hydrogenation Enantioselective synthesis chemistry.chemical_element Phosphanes Bite angle Medicinal chemistry Catalysis Rhodium chemistry.chemical_compound Heterohelicenes chemistry Helicene Asymmetric catalysis Sulfur heterocycles Hydrogenation Itaconic acid Physical and Theoretical Chemistry Helical structures |
| Zdroj: | European journal of organic chemistry (2011): 5649–5658. doi:10.1002/ejoc.201100726 info:cnr-pdr/source/autori:Monteforte, Marco; Cauteruccio, Silvia; Maiorana, Stefano; Benincori, Tiziana; Forni, Alessandra; Raimondi, Laura; Graiff, Claudia; Tiripicchio, Antonio; Stephenson, G. Richard; Licandro, Emanuela/titolo:Tetrathiaheterohelicene Phosphanes as Helical-Shaped Chiral Ligands for Catalysis/doi:10.1002%2Fejoc.201100726/rivista:European journal of organic chemistry (Print)/anno:2011/pagina_da:5649/pagina_a:5658/intervallo_pagine:5649–5658/volume |
| ISSN: | 1434-193X |
| Popis: | Tetrathia[7]helicene-based phosphanes thiaheliphos (2a), nPr-thiaheliphos (2b) and di-nPr-thiaheliphos (2c) have been prepared from the 2,13-dilithio derivatives of thiahelicenes 1a-c by reaction with an excess of Ph2PCl. Protection of the air-sensitive products as BH3 adducts, from which the phosphanes 2a-c are easily regenerated on heating with ethanol, is described. New rhodium(I) complexes 8 and 9 were obtained by reaction of 2c with [Rh(COD)(2)](+)[BF4] and [BARF], respectively, which were converted by oxidation into the chelating phosphane-phosphane oxide Rh-I complexes 10 and 11. The monophosphane 5 was similarly prepared, and reaction of the dilithio species with ClP(O)(OEt)(2) gave the diphosphonate 17, which was characterized by X-ray crystallography. Comparison of data from DFT calculations (B3LYP/SVP) on 2c, 8 and 10 and X-ray data for 17 reveals a strong tension within the thiaheliphos ligands that is partially relaxed by increasing the Rh-P distances and the bite angle of the chelating ligand. Compound (P)-(+)-1c, obtained by chromatographic resolution, was transformed into optically pure (P)-(+)-2c, which was used in the asymmetric hydrogenation of itaconic acid ester and methyl 2-acetamidoacrylate (product ees up to 40%). |
| Databáze: | OpenAIRE |
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