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Diphosphite Ligands (diphosphite + ligand)

Distribution by Scientific Domains

Chemistry	100%

Selected Abstracts

Highly Efficient Rhodium Catalysts for the Asymmetric Hydroformylation of Vinyl and Allyl Ethers using C1 -Symmetrical Diphosphite Ligands

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 2-3 2010
Aitor Gual
Abstract Here, we describe the successful application of novel glucofuranose-derived 1,3-diphosphites in the rhodium-catalysed asymmetric hydroformylation of vinyl acetate, 2,5-dihydrofuran and 2,3-dihydrofuran. In the hydroformylation of vinyl acetate, total regioselectivity and high ee (up to 73%) were obtained. When 2,3- and 2,5-dihydrofuran were the substrates, total chemo- and regioselectivities were achieved together with ees up to 88%. These results correspond to the highest ee values reported to date in the asymmetric hydroformylation of these substrates. The HP-NMR studies of the [RhH(CO)2(L)] species (L=15 and 17) demonstrated that both ligands coordinate to the Rh centre in an eq-eq fashion. The complex [RhH(CO)2(15)] was detected as a single isomer with characteristic features of eq-eq coordination. However, the broadening of the corresponding signals indicated that this species is rapidly interchanging in solution. In contrast, complex [RhH(CO)2(17)] was detected as a mixture of two conformational isomers at low temperature due to the greater flexibility of the monocyclic backbone of this ligand. [source]

Modular Furanoside Diphosphite Ligands for Pd-Catalyzed Asymmetric Allylic Substitution Reactions: Scope and Limitations

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 9 2005
Montserrat Diéguez
Abstract We have synthesized a library of furanoside diphosphite ligands for the Pd-catalyzed allylic substitution reactions of acyclic and cyclic allylic esters. The library has been designed to rapidly screen the ligands to uncover their important structural features and to determine the scope of diphosphite ligands in these catalytic reactions. After the systematic variation of the sugar backbone, the substituent at C-5 and the phosphite moieties, the diphosphite ligand 4c was found to be optimal in the Pd-catalyzed asymmetric allylic substitution of hindered (S1) and unhindered (S2,S5) substrates, yielding high activities [TOFs up to >3000,mol×(mol×h),1] and enantioselectivities (ees up to 99%). In addition, the screening of the library enabled us to find other suitable ligands for hindered disubstituted linear substrate S1 (ligands 1b,d, g and 4b, d, g) and for unhindered cyclic substrates S3,S5 (ligands 6c and 7c). [source]

ChemInform Abstract: Diphosphite Ligands Derived from Carbohydrates as Stabilizers for Ruthenium Nanoparticles: Promising Catalytic Systems in Arene Hydrogenation.

CHEMINFORM, Issue 42 2008
Aitor Gual
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

New C2 -Symmetric Diphosphite Ligands Derived from Carbohydrates: Effect of the Remote Stereocenters on Asymmetric Catalysis.

CHEMINFORM, Issue 51 2007
M. Rosa Axet
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source]

Modular Furanoside Diphosphite Ligands for Pd-Catalyzed Asymmetric Allylic Substitution Reactions: Scope and Limitations

Chiral Diphosphite-Modified Rhodium(0) Nanoparticles: Catalyst Reservoir for Styrene Hydroformylation

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 22 2008
M. Rosa Axet
Abstract The organometallic synthesis of rhodium nanoparticles stabilized with diphosphite ligands is described. These nanoparticles were investigated as catalysts in the styrene hydroformylation reaction, and their activity and selectivity were compared with those of similar molecular complexes. NMR spectroscopic studies performed during the course of the catalytic reaction showed that the synthesized nanoparticles are not stable and produce molecular species. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source]

Modular Furanoside Diphosphite Ligands for Pd-Catalyzed Asymmetric Allylic Substitution Reactions: Scope and Limitations

Carbohydrate-Derived 1,3-Diphosphite Ligands as Chiral Nanoparticle Stabilizers: Promising Catalytic Systems for Asymmetric Hydrogenation

CHEMSUSCHEM CHEMISTRY AND SUSTAINABILITY, ENERGY & MATERIALS, Issue 8 2009
Aitor Gual Dr.
Abstract Metallic Ru, Rh, and Ir nanoparticles were prepared by the decomposition of organometallic precursors under H2 pressure in the presence of 1,3-diphosphite ligands, derived from carbohydrates, as stabilizing agents. Structural modifications to the diphosphite backbone were found to influence the nanoparticles, size, dispersion, and catalytic activity. In the hydrogenation of o - and m -methylanisole, the Rh nanoparticles showed higher catalytic activity than the corresponding Ru nanoparticles. The Ir nanoparticles presented the lowest catalytic activity of the series. In all cases, the hydrogenation of o -methylanisole gave total selectivity for the cis -product, however, the ee of the product was always less than 6,%. A maximum of 81,% cis -selectivity was obtained for the hydrogenation of m -methylanisole, however, no asymmetric induction was observed. These results show that the catalytic activity is affected by a combination of influences from the substrate, the diphosphite ligands, and the metallic nanoparticles. [source]