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  • Palladium  (4)
  • Wiley-Blackwell  (4)
  • 1995-1999  (4)
  • 1965-1969
  • 1998  (4)
  • 1
    Electronic Resource
    Electronic Resource
    The Twofold Heck Reaction on 1,2-Dihalocycloalkenes and Subsequent 6π-Electrocyclization of the Resulting (E, Z, E)-1,3,5-Hexatrienes: A New Formal {2+2+2}-Assembly of Six-Membered Rings (1998)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1998 (1998), S. 1521-1534 
    Details
    ISSN: 1434-193X
    Keywords: Heck reaction ; Cross coupling ; Palladium ; Catalysis ; 6π-Electrocyclization ; Cyclohexa-1,3-dienes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1,6-Disubstituted (E, Z, E)-1,3,5-hexatrienes (4 and 5) were prepared by vicinal twofold Heck coupling reactions from 1,2-dibromocyclopentene (1), 1,2-dibromocyclohexene (2), 1,2-diiodocyclopentene (8), 1,2-diiodocyclohexene (9), 1-bromo-2-trifluoromethanesulfonyloxycyclohex-1-ene (11), or 1-chloro-2-nonafluorobutanesulfonyloxycyclohex-1-ene (19) with alkenes 3, e. g. methyl, tert-butyl, menthyl, 8-phenylmenthyl acrylate, styrene, and alkenylsilanes, respectively, in moderate to mostly good and very good yields (20-92 %). The coupling of alkenylsilanes 3f-k could only be achieved with the 1,2-diiodocycloalkenes 8 and 9, respectively. The corresponding hexatrienes 5 with two different substituents in the 1- and 6-positions were prepared by a sequence of two coupling reactions with different alkenes from 1-chloro-2-nonafluorobutanesulfonyloxycyclo-hex-1-ene (19) or by Wittig-Horner-Emmons olefination of 2-bromocyclohexene-1-carbaldehyde (24) and subsequent Heck reaction of the resulting (E,Z)-bromodienes 25. Several of the hexatrienes (4aa, ee, 5aa, ee, al, am, el) readily underwent a 6π-electrocyclization upon heating in an inert atmosphere to give the 5- or 6-ring-annelated cis-5,6-disubstituted cyclohexadienes 26, 27 (50-95 %). Starting from 5am 2,3-disubstituted tetrahydronaphthalene 28am was formed under oxidative conditions (air) in the reaction and in the work-up procedure. The bissilyl-substituted derivatives 4ff, jj, 5ff did not cyclize under thermal conditions, apparently due to the steric demand of the two silyl substituents which would have to end up cis with respect to each other in the cyclohexadiene products.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Preparation of P,N-Heterodifunctional Ferrocene-Coordinating Ligands by Selective Functionalization of Polyphosphanes by the Staudinger Reaction - Crystal and Molecular Structure of a New Cyclometallaphosphoraniminophosphane of Palladium(II) (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 1359-1368 
    Details
    ISSN: 1434-1948
    Keywords: β-Ferrocenylvinyl azide ; Polyphosphanes ; Iminophosphoranes ; P,N-Difunctional ligands ; Palladium ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Staudinger reactions of the β-ferrocenylvinyl azide 1 with several diphosphanes in a 1:1 molar ratio afford the monoiminophosphorane derivatives 2-4, whereas with a 2:1 stoichiometry these reactions afford the bis(iminophosphoranes) 5-7. Similar results are obtained for the reactions of 1 with tris(diphenylphosphanylmethyl)ethane (triphos) and tris[2-(diphenylphosphanyl)ethyl]phosphane (tetraphos). Reaction of these P,N-difunctional ferrocene ligands with dichlorobis(benzonitrile)palladium(II) leads to the PdII-metallacycle derivatives 13 and 14. The molecular structures of 5d and 13 have been established by X-ray crystallography.
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  • 3
    Electronic Resource
    Electronic Resource
    Insertion Reactions into Palladium-Carbon Bonds of Complexes Containing Terdentate Nitrogen Ligands; Experimental and Ab initio MO Studies (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 1129-1143 
    Details
    ISSN: 1434-1948
    Keywords: Insertion ; N ligands ; Terdentate ligands ; Rigid ligands ; Palladium ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Novel methyl complexes [Pd(Me)(N-N-N)]X (N-N-N = flexible or rigid terdentate nitrogen ligand, X = Cl, SO3CF3, BAr′4) have been synthesized and fully characterized. All complexes readily underwent insertion of carbon monoxide resulting in the quantitative formation of complexes [Pd{C(O)Me}(N-N-N)]X [X = Cl (1d-6d), BAr′4 (1e-6e)]. Subsequently, complexes 2e-6e underwent quantitative insertion of norbornadiene, resulting in complexes [Pd{C7H8C(O)Me}(N-N-N)]BAr′4 (2f-6f). Unexpectedly, these complexes, including even those containing rigid terdentate nitrogen ligands, possess a structure in which the nitrogen ligand is coordinated in a bidentate fashion. A kinetic study of the reaction of norbornadiene with complexes 1e-6e revealed that the reactivity of complexes 1e-6e toward norbornadiene increases with increasing rigidity of the terdentate ligand, i.e. with increasing strain in the PdN3 moiety, which indicates that insertion very likely occurs via a mechanism involving nitrogen dissociation. This is fully supported by ab initio MO calculations on CO and ethylene insertion into carbon-palladium bonds of cationic model systems containing a rigid terdentate nitrogen ligand, which showed that the lowest-energy pathway for both insertion reactions consists of substitution of one of the distal nitrogen atoms of the rigid terdentate nitrogen ligand by the substrate, followed by a rate-determining migratory insertion of the substrate into the carbon-palladium bond.
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  • 4
    Electronic Resource
    Electronic Resource
    Palladium-Catalyzed Self-Cross Coupling of o-Bromo-trans-stilbenes To Yield 9,10-Bis(arylmethylene)-9,10-dihydroanthracenes© (1998)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1998 (1998), S. 2289-2299 
    Details
    ISSN: 1434-193X
    Keywords: Palladium ; Cross coupling ; Arenes ; Cyclizations ; Polycycles ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Under Palladium catalysis [Pd(OAc)2, K2CO3, LiCl, Bu4NBr, DMF] o-bromo-trans-stilbene (trans-7a) reacts to give 9,10-dibenzylidene-9,10-dihydroanthracene (4a) with formation of a new six-membered ring. The (Z) diastereomer crystallizes preferentially to give pure (Z)-4a, as proved by X-ray crystal structure analysis. A variety of substituted o-bromostilbenes and heterocyclic analogs 7 were prepared by Wittig olefination of o-bromobenzaldehyde with substituted benzyltriphenylphosphonium ylides, Wittig-Horner-Emmons olefination of arenecarbaldehydes with diethyl o-bromobenzylphosphonate or Wittig olefination of substituted benzaldehydes with substituted (o-bromobenzyl)-diphenylphosphonium ylides, respectively. The cis-o-bromostilbenes were photoisomerized to the trans diastereoisomers trans-7 by irradiation in the presence of diphenyl disulfide. All of these o-bromo-trans-stilbenes trans-7a-g and trans-7j, k under palladium catalysis reacted to the corresponding 9,10-bis(arylmethylene)-9,10-dihydroanthracenes 4, mostly as mixtures of (E) and (Z) diastereomers (50-97 % yield). The (Z) diastereomer of the parent 4a and the alkyl-substituted compounds 4c and 4e could be purified by simple crystallization, and in some runs, only (Z)-4a, c, e were obtained. Among the heterocyclic analogs trans-7h, i only the furyl derivative trans-7h reacted (76 % yield) cleanly, whereas the pyridine analog trans-7i gave a mixture of products from which the rather sensitive product 4i could not be isolated in pure form. The cis-o-bromostilbenes cis-7a, c cyclized to phenanthrenes under the same conditions (70-71 % yield). The UV spectra of compounds 4a, c-k are similar to that of anthracene, and so are the oxidation and reduction potentials of (Z)-4a.
    Additional Material: 1 Ill.
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