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  • Carbene complexes of chromium and tungsten  (3)
  • 1-Metalla-1,3-dienes  (2)
  • Cyclopentadienes  (2)
  • (2,3,4,6-Tetra-O-pivaloyl-β-D-galactopyranosylamine, carbene complexes of  (1)
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Keywords
  • 1
    Electronic Resource
    Electronic Resource
    Organische Synthesen mit übergangsmetall-Komplexen, 51. 1-Metalla-1,3,5-triene und 1-Metalla-1,3-dien-5-ine von Chrom und Wolfram durch Insertion von Alkinen in M=C- bzw. C=C-Bindungen von 1-Metalla-1,3-dienen bzw. 1-Metalla-1-en-2-inen (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1229-1236 
    Details
    ISSN: 0009-2940
    Keywords: Carbene complexes of chromium and tungsten ; 1-Metalla-1,3,5-trienes ; 1-Metalla-1,3-dien-5-ynes ; Insertion of alkynes into M=C and C=C bonds ; [2 + 2] Cycloaddition reactions of carbene complexes and alkynes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Organic Syntheses via Transition Metal Complexes, 51. - 1-Metalla-1,3,5-trienes and 1-Metalla-1,3-dien-5-ynes of Chromium and Tungsten by Insertion of Alkynes into M=C and C=C Bonds of 1-Metalla-1,3-dienes and 1-Metalla-1-en-3-ynes, respectively1-Metalla-1,3,5-trienes LnM=C(NEt2)-C(Me)—C(OEt)-CH=CHPh (3,4) and LnM=C(OEt)- CH=C(NEt2) - C(Me)=CHPh [5, LnM=Cr(CO)5 (a), W(CO)5 (b)] are obtained for the first time from the corresponding 1-metalla-1,3-dienes LnM=C(OEt) - CH=CHPh (1a, b) under very mild conditions by the insertion of the electron-rich alkyne Et2N-C ≡ C - Me (2) into the M=C and the C=C bonds, respectively, of 1. The chelate complex (6b) and the cyclobutenyl carbene complex 7b are isolated as minor side products. 1-Metalla-1,3-dien-5-ynes LnM=C(NEt2) - C(Me)=C(OEt) - C ≡ CPh [9, 10, LnM=Cr(CO)5 (a), W(CO)5 (b)] are formed with high regio- and stereoselectivity on insertion of 2 into the M=C bonds of 1-metalla-1-en-3-ynes 8. X-ray data are given for the tungsten complex 3b.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19911240541
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  • 2
    Electronic Resource
    Electronic Resource
    Organische Synthesen mit Übergangsmetallkomplexen, 46. Alkenylcarben-Chrom- und -Wolframkomplexe; Protonierung und Aktivierung durch Elektronen-ziehende Substituenten (1990)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 123 (1990), S. 1847-1852 
    Details
    ISSN: 0009-2940
    Keywords: Carbene complexes of chromium and tungsten ; Alkenylcarbene complexes, protonation of ; β-(Acylamino)alkenyl complexes of chromium ; Activated aminocarbene complexes ; 1-Metalla-1,3-dienes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Organic Syntheses via Transition Metal Complexes, 46.  -  Alkenylcarbene Chromium and Tungsten Complexes; Proton Addition and Activation by Electron-Withdrawing SubstituentsAlkenylcarbene complexes LnM=C(OEt)-CH=C(R)NMe2[1, LnM = Cr(CO)5, W(CO)5; R = H, CH3, C6H5] add HBF4 in ether to give novel cationic carbene complexes [Ln M=C(OEt)-CH2-C(R)=NMe2]BF4 (3) by protonation at C-2 of the =C-C=C ligand. The addition of HBF4 to 7 leads to the formation of the cyclic carbene complexes 8. Structures of 3 and 8 are assigned spectroscopically. X-ray data are reported for 8a. Protonation of 1 and 7 results in a strong deshielding of the carbene carbon atoms, which parallels an increase of reactivity at the M=C bonds. An activation of the M=C bond has also been achieved by electron-withdrawing substituents like N-acyl groups. We report on the first synthesis of [β-(acylamino)-alkenyl]carbene complexes 13, which are more reactive than β-(aminoalkenyl)carbene complexes 7.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19901230916
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  • 3
    Electronic Resource
    Electronic Resource
    Organische Synthesen mit Übergangsmetall-Komplexen, 50 2H-Pyrrol-Komplexe durch stufenweise Insertion von Alkinen und Isocyaniden in M=C-Bindungen von Chrom- und Wolfram-Carbenkomplexen (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 213-218 
    Details
    ISSN: 0009-2940
    Keywords: Carbene complexes of chromium and tungsten ; 1-Metalla-1,3-dienes ; Insertion of alkynes and isocyanides into M = C bonds ; 2H-Pyrrole complexes of chromium and tungsten ; [1+2+2] Cycloaddition reactions of carbene complexes, alkynes and isocyanides ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Organic Syntheses via Transition Metal Complexes, 501). - 2H-Pyrrole Complexes by a Stepwise Insertion of Alkynes and Isocyanides into M=C Bonds of Carbene Chromium or Tungsten Complexes2H-Pyrrole complexes 6a, b are obtained in two step by [1+2+2] cycloaddition reactions of the carbene complex (CO)5W=C(OEt)C6H5 (1d), the alkyne EtO-C≡CH (2) and isocyanides R1-NC 4a, b [R1 = CH3, c-C6H11). Ln=C(OEt)R 1 [LnM = Cr(CO)5, W(CO)5; R = C6H5, CH3] reacts with 2 to give 1-metalla-1,3-dienes 3a-d. (E)/(Z)-3d and 4 yield 6a, b via 1-aza-1,2,4-pentatriene complexes 5, which are open-chain precursors of 6. 2H-Pyrrole complexes 11 and 14 are synthesized in overall [2+1+2] cycloadditions withe reversed connectivity, or formation of 1-chroma-1,3-dienes 10 and 13 by condensation of the methylcarbene complex 1a with acid amides, and cyclisation again with isocyanides 4.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19911240132
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  • 4
    Electronic Resource
    Electronic Resource
    Organische Synthesen mit Übergangsmetallkomplexen, 70. [2-(Galactopyranosylamino)ethenyl]carben- und 3-(Galactopyranosylamino)-1,2-propadienyliden-Komplexe durch 3-Addition von 2,3,4,6-Tetra-O-pivaloyl-β-D-galactopyranosylamin an Alkinylcarben-Komplexe (M = Cr, W).  -  Atropisomere Galactopyranosyl-Pyrrole durch Reaktion von [2-(Galactopyranosylamino)ethenyl]carben-Komplexen mit Isocyaniden (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 725-729 
    Details
    ISSN: 0009-2940
    Keywords: [2-(Amino)ethenyl]carbene complexes ; 3-Amino-1,2-propadienylidene complexes ; (2,3,4,6-Tetra-O-pivaloyl-β-D-galactopyranosylamine, carbene complexes of ; Ketene imines ; Isocyanides ; Pyrroles ; Alkynylcarbene complexes of chromium and tungsten ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Organic Syntheses via Transition Metal Complexes, 70[1].  -  [2-(Galactopyranosylamino)ethenyl]carbene and 3-(Galactopyranosylamino)-1,2-propadienylidene Complexes on 3-Addition of 2,3,4,6-Tetra-O-pivaloyl-β-D-galactopyranosylamine to Alkynylcarbene Complexes (M = Cr, W).  -  Atropisomeric Galactopyranosyl Pyrroles by Reaction of [2-(Galactopyranosyl-amino)ethenyl]carbene Complexes with IsocyanidesEnantiomeric pure (2-aminoethenyl)carbene complexes LnM=C(OEt)—CH=C(Ph)NHR* (Z)-3 and 3-amino-1,2-propadienylidene complexes LnM=C=C=C(Ph)NHR* 4 [R* = 2,3,4,6-tetra-O-pivaloyl-β-D-galactopyranosyl] are obtained by the addition of galactopyranosylamine R*-NH2 2 to the corresponding alkynylcarbene complexes LnM=C(OEt)—C≡CPh 1 [LnM = (CO)5Cr, (CO)5W]. Treatment of (Z)-3 with two equivalents of tert-butyl isocyanide (5) affords isocyanide complexes 6 and ketene imines 7. The latter cyclize spontaneously to give galactopyranosylpyrroles 8 which form stable atropisomers 8A and 8B.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270423
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  • 5
    Electronic Resource
    Electronic Resource
    Uncovering Reaction Pathways of 1-Aminocyclohexenes with [(1-Alkynyl)carbene]tungsten Complexes Leading to Cyclopentadienes and Dihydropyrroles (2000)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 37-49 
    Details
    ISSN: 1434-193X
    Keywords: Carbene complexes ; Enamines ; Metallatrienes ; Cyclopentadienes ; Dihydropyrroles ; spiro-Tetrahydropyrroles ; Iminium carbonylmetalates ; Dimetallapolyenes ; Tungsten ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Reactions of the [(1-alkynyl)carbene]tungsten complex (CO)5W=C(OEt)C≡CPh (1) with 1-aminocyclohexenes 2a-c and 7a-c afford different types of products depending on the amino substituents and the reaction conditions. (4-Aminocyclobutenyl)carbene complexes B have been shown to be generated in the first reaction step through a [2+2] cycloaddition. These are key intermediates and afford cross-conjugated tungstatrienes E, (conjugated) 1-tungsta-1,3,5-hexatrienes G, or (non-conjugated) 1-tungsta-1,3,6-heptatrienes F by following competing reaction pathways. Cross-conjugated 1-tungstatrienes 3 have been isolated in 52-74% yield by performing the reactions of 1-aminobenzocyclohexenes 2a-c with compound 1 in pentane. In dichloromethane instead of pentane, (conjugated) 1-tungsta-1,3,5-hexatrienes 4 are obtained, which subse-quently undergo fragmentation to give cyclopentadienes 6 (by π-cyclization) and dihydropyrroles (by α-cyclization) in a molar ratio dependent on the nature of the amino substituents. (Non-conjugated) 1-tungsta-1,3,6-heptatrienes 10 are generated upon reaction of 1-aminocyclohexenes 7a-c with compounds 1, which are transformed into cyclopentadienes 12 via conjugated 1-tungsta-1,3,5-hexatrienes 9 as intermediates. Reactions of 1-tungsta-1,3,6-heptatrienes 10 with the (1-alkynyl)carbene complex 1 afford dinuclear compounds 14, which subsequently yield indenes 15 (by two successive π-cyclization steps) and spiro-tetrahydropyrroles 16 (by both a π-cyclization and an α-cyclization step), depending on the steric bulk of the amino substituent.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    1,3-Dioxycyclopentadienes from (1-Alkynyl)carbene Tungsten Complexes - Domino Cyclization/Cycloaddition Reactions (2000)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 1183-1192 
    Details
    ISSN: 1434-193X
    Keywords: Carbene complexes ; 1-Metallahexatrienes ; Cyclopentadienes ; Carbene complexes ; Tungsten ; Domino cyclization ; Pentalenes ; Spirocyclopentanes ; Spiro compounds ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -1,3-Dioxytetrahydropentalenes 9 have been generated by base-catalyzed addition of protic oxygen nucleophiles ROH 6a-g (RO = carboxy or phenyloxy) to the [2-(1-cyclopentenyl)ethynyl]carbene tungsten complex 3. Compounds 9 are highly reactive and afford (cyclobutenyl)carbene complexes 12a-g through spontaneous [2+2] cycloaddition to a second molecule of the (1-alkynyl)carbene complex 3. Thermolysis of compounds 12 was found to generate indeno[b]-spiro-tricyclo[5.3.0.0]decadienes 18 through π-cyclization of the 1-tungsta-1,3,5-hexatriene unit involving insertion of carbon monoxide into the W—C bond.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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