Endre søk
Begrens søket
1 - 7 of 7
RefereraExporteraLink til resultatlisten
Permanent link
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Treff pr side
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
  • Disputationsdatum (tidligste først)
  • Disputationsdatum (siste først)
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
  • Disputationsdatum (tidligste først)
  • Disputationsdatum (siste først)
Merk
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 1.
    Carrasco, Sergio
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Sanz-Marco, Amparo
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Martin-Matute, Belén
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Fast and Robust Synthesis of Metalated PCN-222 and Their Catalytic Performance in Cycloaddition Reactions with CO22019Inngår i: Organometallics, ISSN 0276-7333, E-ISSN 1520-6041, Vol. 38, nr 18, s. 3429-3435Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A simple and quick setup for the synthesis of PCN-222 and of a variety of metalated PCN-222(Co, Ni, Cu, and Zn), using of a microwave reactor, is reported for CO2 fixation. Metalation of prophyrins by microwave heating has been evaluated through UV-vis titration. PCN-222(M) were obtained in a three-step, one-pot reaction in a remarkable 72% yield in only 30 min. The materials have been characterized using a variety of techniques. A study of CO2 fixation through cycloaddition with epoxides and azidirines using metalated PCNs as catalysts is described. Cyclic carbonates and oxazolidinones were formed using CO2 at atmospheric pressure under mild conditions. Higher activity was observed when PCN-222(Co) was used compared to that with PCN-222(Ni, Cu, Zn).

  • 2.
    González Miera, Greco
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Martínez-Castro, Elisa
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Martín-Matute, Belén
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Acceptorless Alcohol Dehydrogenation: OH vs NH Effect in Bifunctional NHC–Ir(III) Complexes2018Inngår i: Organometallics, ISSN 0276-7333, E-ISSN 1520-6041, Vol. 37, nr 5, s. 636-644Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Bifunctional complexes bearing N-heterocyclic carbene (NHC) ligands functionalized with hydroxy or amine groups were synthesized to measure the beneficial effect of different modes of metal–ligand cooperation in the acceptorless dehydrogenation of alcohols. In comparison to complexes with an amine moiety, hydroxy-functionalized iridium catalysts showed superior activity. In contrast to alcohols, 1,4-diols underwent cyclization to give the corresponding tetrahydrofurans without involving dehydrogenation processes. Mechanistic investigations to rationalize the “OH effect” in these types of complexes have been undertaken.

  • 3.
    Kalek, Marcin
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Stawinski, Jacek
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Palladium-catalyzed C-P bond formation: Mechanistic studies on the ligand substitution and the reductive elimination. An intramolecular catalysis by the acetate group in PdII complexes2008Inngår i: Organometallics, ISSN 0276-7333, E-ISSN 1520-6041, Vol. 27, nr 22, s. 5876-5888Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Ligand substitution and reductive elimination of the palladium-catalyzed C−P bond forming cross-coupling were investigated in depth. It was found that for PhPdII(PPh3)2X (X = I, Br, Cl) complexes, a step commonly referred to as ligand substitution commenced with coordination of an H-phosphonate diester, followed by its deprotonation to form an equilibrium mixture of penta- and tetracoordinate palladiumphosphonate intermediates, from which reductive elimination of the product (diethyl phenylphosphonate) occurred. For the acetate counterpart, PhPdII(PPh3)2(OAc), the incorporation of a phosphonate moiety to the complex was preceded by a rate-determining removal of the supporting phosphine ligand, facilitated by an intramolecular catalysis by the acetate group. Both the reaction steps, i.e., formation of palladiumphosphonate intermediates and reductive elimination, were significantly faster for the acetate versus halides containing PdII complexes investigated. Similar observations were found to be true also for bidentate ligand complexes [(dppp)PdII(Ph)X]; however, in this instance, a single palladiumphosphonate intermediate, (dppp)PdII(Ph)(PO(OEt)2), could be observed by 31P NMR spectroscopy. The synthetic and kinetic studies on the cross-coupling reaction of diethyl H-phosphonate with phenyl halides permitted us to elucidate a crucial catalytic role of an acetate group in PdII complexes and to propose two distinctive catalytic cycles, which complemented traditional Pd0/PdII schemes, for the palladium-mediated C−P bond formation.

  • 4.
    Kalek, Marcin
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Stawinski, Jacek
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Pd(0)-Catalyzed phosphorus-carbon bond formation: Mechanistic and synthetic studies on the role of the palladium sources and anionic additives2007Inngår i: Organometallics, ISSN 0276-7333, E-ISSN 1520-6041, Vol. 26, nr 24, s. 5840-5847Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Pd(PPh3)4, Pd(dba)2, Pd(OAc)2, and PdCl2, have been evaluated as possible Pd(0) sources for the palladium-catalyzed P−C bond formation via a cross-coupling of aryl halides with H-phosphonate diesters. It was found that the most efficient catalytic system can be generated from Pd(OAc)2 with a key role being played by Pd(II) and Pd(0) species with coordinated acetate ions. The reactivity of differently ligated Pd(II) complexes was determined, and 31P NMR spectroscopy studies were carried out to provide mechanistic interpretations for the observed differences between the catalytic systems.

  • 5. Kleimark, Jonatan
    et al.
    Johansson, Charlotte
    Olsson, Susanne
    Håkansson, Mikael
    Hansson, Sverker
    Åkermark, Björn
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Norrby, Per-Ola
    Sterically goverend selectivity in palladium-assisted allylic alkylation2011Inngår i: Organometallics, ISSN 0276-7333, E-ISSN 1520-6041, Vol. 30, s. 230-238Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The selectivity in the Pd-assisted allylic alkylation has been investigated in a system with a ligand tethered to the allylic moiety. Isolation of (η3-allyl)Pd complexes and stoichiometric reaction with malonate nucleophiles allowed separation of various factors influencing the regioselectivity in a system that cannot undergo apparent rotation. Unexpectedly, trans effects were found to have only a minor influence on the selectivity, whereas changing the tether length could shift the preference from favored internal to dominant terminal attack. DFT-assisted analysis revealed that the dominant selectivity-determiningfactors are the forced rotation of the allylic moiety and an important steric repulsion from a syn-alkyl substituent

  • 6.
    Niclas, Solin
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Szabó, Kálmán J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Mechanism of the η3-η1-η3 Isomerization in Allylpalladium Complexes: Solvent Coordination, Ligand, and Substituent Effects2001Inngår i: Organometallics, ISSN 0276-7333, E-ISSN 1520-6041, Vol. 20, s. 5464-5471Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The mechanism of the η3 → η1 → η3 isomerization of (η3-allyl)palladium complexes occurring as catalytic intermediates in important synthetic transformations has been studied by applying density functional theory at the B3PW91(DZ+P) level. It was found that under catalytic conditions, in the condensed phase, the isomerization process involves tetracoordinated (η1-allyl)palladium intermediates. In these intermediates a solvent molecule or another ancillary ligand coordinates to palladium. The stability of the (η1-allyl)palladium intermediates critically depends on the electronic effects and on the coordination ability of the solvent molecules and the ancillary ligands. The theoretical calculations indicate a dσ → π* type hyperconjugative interaction occurring in the η1-allyl moiety of the intermediary complexes. These hyperconjugative interactions influence the structure of the complexes and the activation barrier to rotation through the C1−C2 bond. Alkyl substitution of the metalated carbon leads to destabilization of the (η1-allyl)palladium complexes, which increases the activation energy of the syn/anti isomerization process. This substituent effect arises from a dual steric and electronic destabilizing interaction between the methyl substituent and the metal atom.

  • 7. Sawadjoon, Supaporn
    et al.
    Orthaber, Andreas
    Sjöberg, Per J. R.
    Eriksson, Lars
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Samec, Joseph S. M.
    Equilibrium Study of Pd(dba)(2) and P(OPh)(3) in the Pd-Catalyzed Allylation of Aniline by Allyl Alcohol2014Inngår i: Organometallics, ISSN 0276-7333, E-ISSN 1520-6041, Vol. 33, nr 1, s. 249-253Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Reaction of Pd(dba)(2) and P(OPh)(3) shows a unique equilibrium where the Pd[P(OPh)(3)](3) complex is favored over both Pd(dba)[P(OPh)(3)](2) and Pd[P(OPh)(3)](4) complexes at room temperature. At a lower temperature, Pd[P(OPh)(3)](4) becomes the most abundant complex in solution. X-ray studies of Pd[P(OPh)(3)](3) and Pd(dba)[P(OPh)(3)](2) complexes show that both complexes have a trigonal geometry with a Pd-P distance of 2.25 angstrom due to the pi-acidity of the phosphite ligand. In solution, pure Pd(dba)[P(OPh)(3)](2) complex equilibrates to the favored Pd[P(OPh)(3)](3) complex, which is the most stable complex of those studied, and also forms the most active catalytic species. This catalyst precursor dissociates one ligand to give the reactive Pd[P(OPh)(3)](2), which performs an oxidative addition of nonmanipulated allyl alcohol to generate the pi-allyl-Pd[P(OPh)(3)](2) intermediate according to ESI-MS

1 - 7 of 7
RefereraExporteraLink til resultatlisten
Permanent link
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf