Regio- and Stereoselective Hydroformylation of Glucal Derivatives with Rhodium Catalysts

Fernández, Elena; Ruiz, Aurora; Claver, Carmen; Castillón, Sergio; Polo, A.; Piniella, J. F.; Álvarez‐Larena, Ángel

doi:10.1021/om971010k

Cited by 53 publications

(29 citation statements)

References 37 publications

(35 reference statements)

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“…The Rh À P bond lengths are around 2.18 ä, while the Rh À C and Rh À Cl lengths are around 1.80 ± 1.81 ä and 2.41 ± 2.42 ä, respectively. All these data compare well with the values found in the mononuclear complex [RhCl(CO){P(OPh) 3 } 2 ] [40] with the exception of the Rh-P bonds, which are around $ 0.1 ä shorter in Two other dinuclear rhodium-phosphite complexes with a similar conformation have been characterized by X-ray crystallography. Cobley et al have described the reaction of a calixarene based monophosphite with [RhCl(CO) 2 ] 2 at different stoichiometries, always ending up with a mixture of two complexes in the ratio 1 to 4, based on the 31 P NMR spectrum.…”

supporting

confidence: 84%

Versatile Phosphite Ligands Based on Silsesquioxane Backbones

et al. 2004

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Silsesquioxanes are employed as ligand backbones for the synthesis of novel phosphite compounds with 3,3'-5,5'-tetrakis(tert-butyl)-2,2'-dioxa-1,1'-biphenyl substituents. Both mono-and bidentate phosphites are prepared in good yields. Two types of silsesquioxanes are employed as starting materials. The monophosphinite 1 and the monophosphite 2 are prepared from the thallium silsesquioxide derived from a completely condensed silsesquioxane framework (c-C 5 H 9 ) 7 Si 7 O 12 SiOTl. The diphosphite 3 is synthesized starting with the incompletely condensed monosilylated disilanol (c-C 5 H 9 ) 7 Si 7 O 9 (OSiMePh 2 )(OH) 2 . For monophosphite 2, the corresponding trans-[PtCl 2 (2)] complex 4 is characterized by NMR spectroscopy as well as by Xray crystallography, as the first example of a completely condensed oxo-functionalized silsesquioxane framework. The coordination of the bidentate ligand 3 towards Pd, Mo and Rh is studied, both by NMR spectroscopy as well as by X-ray crystallography.

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confidence: 84%

Versatile Phosphite Ligands Based on Silsesquioxane Backbones

et al. 2004

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“…This observation is consistent with the s-accepting borane moiety of DPB somewhat compensating for the presence of the two s-donating dialkylphosphine moieties, such that the combined electronic characteristics of the DPB ligand resemble, to some extent, those of p-accepting diphosphonites or diphosphites. [28] These results provide the first reliable estimation of the electron-withdrawing effect of borane coordination. [29,30] …”

mentioning

confidence: 93%

Ambiphilic Diphosphine–Borane Ligands: Metal→Borane Interactions within Isoelectronic Complexes of Rhodium, Platinum and Palladium

Bontemps

Sircoglou

Bouhadir

et al. 2007

Chemistry A European J

160

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Coordination of an ambiphilic diphosphine-borane (DPB) ligand to the RhCl(CO) fragment affords two isomeric complexes. According to X-ray diffraction analysis, each complex adopts a square-pyramidal geometry with trans coordination of the two phosphine buttresses and axial RhB contacts, but the two differ in the relative orientations around the rhodium and boron centres. DFT calculations on the actual complexes provide insight into the influence of the pi-accepting CO co-ligand, compared with previously reported complexes [Rh(mu-Cl)(dpb)]2 and [RhCl(dmap)(dpb)]. In addition, comparison of the nu(CO) frequency of [RhCl(CO)(dpb)] with that of the related borane-free complex [RhCl(CO)(iPr2PPh)2] substantiates the significant electron-withdrawing effect that the sigma-accepting borane moiety exerts on the metal. Valence isoelectronic [PtCl2(dpb)] and [PdCl2(dpb)] complexes have also been prepared and characterized spectroscopically and structurally. The pronounced influence of the transition metal on the magnitude of the M-->B interaction is highlighted by geometric considerations and NBO analyses.

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“…All hydrogens atoms and solvent molecules are omitted for clarity. Selected bond lengths (Å) and angles (Њ): Rh-P 1 2.2554(9), Rh-P 2 2.2554(9), Rh-Cl 2.3840(3), Rh-C 1 1.818 (5) 42 Paciello and co-workers published two crystal structures based on ligands known from the patent literature, where the two phosphite groups are clearly coordinated in a cis-fashion to the rhodium. No spectroscopic or crystallographic data were given for these complexes.…”

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confidence: 99%

Coordination chemistry and X-ray studies with novel sterically constrained diphosphonite ligands

et al. 2003

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The coordination of two novel, sterically constrained diphosphonite ligands towards different palladium, platinum and rhodium precursors has been studied. Complexes of this hitherto unexplored class of diphosphonites, based on rigid xanthene backbones, have been characterized by X-ray crystallography as well as by NMR and IR spectroscopy. A short and concise overview is given on the scarce literature on phosphonite related chemistry. Structural differences in the complexes obtained due to steric influences of the ligands are discussed. Ligand 1, bearing 2-tert-butylphenolate groups, led to orthometallated complexes cis-[MCl{1-κ 3 C,P,P}] (M = Pd, Pt) and to trans- [RhCl(CO) (1)]. These complexes were compared with those formed with ligand 2, bearing 2,2Ј-dioxo-3,3Ј-di-tert-butyl-5,5Ј-dimethoxy-1,1Ј-biphenyl groups, preventing orthometallation. The complexes trans-{PdCl 2 (2)], cis-[PtCl 2 (2)] and trans-[RhCl(CO)(2)] were structurally characterized. Valuable data were collected on chemical shifts, Pt-P coupling constants, as well as CO stretch frequencies of Rh-CO complexes as important tools for structural characterization of such complexes. IntroductionProgress and development of homogeneous catalysis is very much related and dependent on the synthesis and availability of ligands. In recent years a number of powerful new ligand classes have emerged, most of which are chelating phosphorusbased compounds 1 such as phosphines 2 or phosphites.3 Phosphonites however have been widely neglected and only very recently a few examples were reported. Reetz et al. used several backbones, amongst others ferrocene, to prepare chelating diphosphonites and used them in asymmetric Rh-catalyzed hydrogenations of the typical benchmark substrates 4 as well as in conjugate addition of aryl boronic acids.5 ZanottiGerosa et al. also described diphosphonites but they used the para-cyclophane backbone and performed hydrogenation reactions.6 Pringle andco-workers used binaphthol-derived mono-and bidentate phosphonites for conjugate additions of diethyl zinc to enones. 7 The same monophosphonites were used by Claver and Pringle in asymmetric hydrogenations.8 Scharf and co-workers used the monodentate phosphonites based on TADDOL as the chiral auxiliary for the rhodum-catalyzed hydrosilylation of ketones.9 Börner and co-workers have published on the use of both monodentate and bidentate phosphonite ligands in the hydroformylation of alkenes, with varying results.10 Finally the Reetz group, in line with their earlier work, prepared phosphite-phosphonite bidentate ligands but no applications in catalysis were reported so far. 11During recent years xanthene-based chelating ligands have been introduced and extensively used in transition metal catalyzed C-C bond forming reactions.12 These backbones provide a unique combination of rigidity and P-P distance in such a way, that specific, large bite-angle coordination modes are supported. Additionally interaction of the central oxygen atom in the backbone with a metal atom coordinated is possible...

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Regio- and Stereoselective Hydroformylation of Glucal Derivatives with Rhodium Catalysts

Cited by 53 publications

References 37 publications

Versatile Phosphite Ligands Based on Silsesquioxane Backbones

Versatile Phosphite Ligands Based on Silsesquioxane Backbones

Ambiphilic Diphosphine–Borane Ligands: Metal→Borane Interactions within Isoelectronic Complexes of Rhodium, Platinum and Palladium

Coordination chemistry and X-ray studies with novel sterically constrained diphosphonite ligands

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