36267-33-1Relevant academic research and scientific papers
Enantioselective supramolecular catalysis induced by remote chiral diols
Van Leeuwen, Piet W. N. M.,Rivillo, David,Raynal, Matthieu,Freixa, Zoraida
supporting information; experimental part, p. 18562 - 18565 (2012/01/31)
A new method of creating libraries of chiral diphosphines is presented. Supramolecular coordination compounds based on Ti, Rh, achiral ditopic ligands, and chiral diols were synthesized by in situ mixing and used as catalysts in the asymmetric hydrogenation of (Z)-methyl 2-acetamido-3-phenylacrylate, giving ee's of up to 92%. The ditopic ligands contain a Schiff base that coordinates to the assembly metal Ti and a phosphine as a ligand for Rh. Chirality is introduced by coordination of the chiral diols to Ti. The controlling chiral center and the substrate are separated by as much as 13 A.
Cooperative effect of a classical and a weak hydrogen bond for the metalInduced construction of a self-assembled β-turn mimic
Laungani, Andy C.,Keller, Manfred,Slattery, John M.,Krossing, Ingo,Breit, Bernhard
experimental part, p. 10405 - 10422 (2010/04/05)
A novel metal-induced template for the self-assembly of two independent phosphane ligands by means of unprecedented multiple noncovalent interactions (classical hydrogen bond, weak hydrogen bond, metal coordination, π-stacking interaction) was developed and investigated. Our results address the importance and capability of weak hydrogen bonds (WHBs) as important attractive interactions in selfassembling processes based on molecular recognition. Together with a classical hydrogen bond, WHBs may serve as promoters for the specific self-assembly of complementary monomeric phosphane ligands into supramolecular hybrid structures. The formation of an intermolecular C-H...N hydrogen bond and its persistence in the solid state and in solution was studied by X-ray crystal analysis, mass spectrometry and NMR spectroscopy analysis. Further evidence was demonstrated by DFT calculations, which gave specific geometric parameters for the proposed conformations and allowed us to estimate the energy involved in the hydrogen bonds that are responsible for the molecular recognition process. The presented template can be regarded as a new type of self-assembled β-turn mimic or supramolecular pseudo amino acid for the nucleation of β-sheet structures when attached to oligopeptides.
Catalysis by design: Wide-bite-angle diphosphines by assembly of ditopic ligands for selective rhodium-catalyzed hydroformylation
Rivillo, David,Gulyas, Henrik,Benet-Buchholz, Jordi,Escudero-Adan, Eduardo C.,Freixa, Zoraida,Van Leeuwen, Piet W. N. M.
, p. 7247 - 7250 (2008/09/17)
The assembly makes the bite! Ditopic ligands comprising an anionic N-O or N-N moiety (shown in blue and gray) and a phosphine moiety (orange) can be assembled with hard metals such as zinc(II) (green) to form bidentate phosphine ligands. This approach led to a rhodium catalysts for the selective hydroformylation of 1-octene with linear-to-branched ratios up to 21:1 and rates comparable to covalently bound wide-bite-angle diphosphine ligands. (Figure Presented).
Ionic interaction as a powerful driving force for the formation of heterobidentate assembly ligands
Gulyas, Henrik,Benet-Buchholz, Jordi,Escudero-Adan, Eduardo C.,Freixa, Zoraida,Van Leeuwen, Piet W. N. M.
, p. 3424 - 3430 (2008/01/06)
An ionic interaction has been used for the first time to assemble monophosphane ligands. NMR spectroscopy and X-ray studies show that cationic and anionic triphenylphosphane derivatives form ion pairs and subsequently act as a ligand in various transition-metal complexes. The position of the ionic functional groups allows both cis and trans coordination of the novel assembly ligand in square-planar transition-metal complexes.
Water Soluble Cationic Phosphine Ligands Containing m-Guanidinium Phenyl Moieties. Syntheses and Applications in Aqueous Heck Type Reactions
Hessler, Antonella,Stelzer, Othmar,Dibowski, Harald,Worm, Karin,Schmidtchen, Franz P.
, p. 2362 - 2369 (2007/10/03)
Cationic phosphine ligands containing m-guanidinium phenyl substituents {Ph3-nP[C6H4-m-NHC(NH2)(NMe 2)]n}n+ nCl- (n = 1-3) (17a-c) have been obtained by addition of dimethylcyanamide to the amino groups of tertiary (m-aminophenyl)phosphines in acidic medium. The tertiary (m-aminophenyl)phosphines Ph3-nP(C6H4-m-NH2)n (4a-c) were prepared by reaction of (3-[N,N-bis(trimethylsilyl)amino]phenyl)magnesium chloride (1) with chlorophosphines Ph3-nPCln followed by deprotection of the bis(trimethylsilyl)amino groups with methanol. Using a similar protected group synthesis as above, the secondary (m-aminophenyl)phosphine Ph(H)PC6H4-m-NH2 (7) could be prepared as well. It may be employed as a building block for the syntheses of chiral bidentate phosphine ligands (11, 14, and 15) bearing m-aminophenyl substituents. The guanidinium phosphines 17b and 17c are readily soluble in water. A comparative study of 17b and 17c, the aryl alkyl guanidinium phosphines 18 and 19, and TPPTS (P(C6H4-m-SO3Na)3) in the aqueous phase palladium-catalyzed C-C coupling reaction between p-iodobenzoate and (trifluoroacetyl)propar-gylamine shows 17b to be of surmounting activity.
