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  • 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, 53 4-Methylencyclopentene und 5-Methylencyclohexenone aus „Fischer-Carben“- Chromkomplexen, Allenen und Alkine (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2335-2342 
    Details
    ISSN: 0009-2940
    Keywords: Cyclopentenes, 4-methylene-, synthesis of ; Cyclohexenones, 5-methylene-, synthesis of ; Tri(methylene)-methane chromium complexes ; [3 + 2]Cycloadditions with tri(methylene)methane complexes ; Carbene chromium complexes for organic synthesis ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Organic Syntheses via Transition Metal Complexes, 53.  -  4-Methylenecyclopentenes and 5-Methylenecyclohexenones from “Fischer Carbene” Chromium Complexes, Allenes, and AlkynesA method is described for the two-step construction of 4-methylenecyclopentenes 6 and 5-methylenecyclohexenones 7 from Fischer carbene chromium complexes, allenes, and alkynes. In the first step a tri(methylene)methane complex 3 is generated by the addition of the carbene chromium complex (CO)5Cr = C(0Et)Ph (1) to the allene 2. The second step involves an addition of 3 to alkynes HC≡CR [5: R = Ph (a), SiMe3 (b)] at 75°C to give 6 and/or 7 in high chemical yields. The product ratios strongly depend on the substituents R.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19911241029
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  • 3
    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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  • 4
    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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  • 5
    Electronic Resource
    Electronic Resource
    Organische Synthesen mit Übergangsmetall-Komplexen, 60. Neuartige Benzoanellierung mit Carben-Komplexen und Alkinen. - 2-Oxybenzoanellierung von Cycloheptatrien über (Cycloheptatrienylmethyl)-carben-Komplexe von Chrom und Wolfram (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 1861-1864 
    Details
    ISSN: 0009-2940
    Keywords: Carbene complexes, cycloaddition reactions of ; Carbene complexes, reactions with alkynes ; Benzocyclo-heptatrienes ; 2-Oxybenzoanellation ; (Cycloheptatrienylmethyl)carbene 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, 60. - Novel Type of Benzoanellation with Carbene Complexes and Alkynes. - 2-Oxybenzoanellation of Cycloheptatriene via (Cycloheptatrienylmethyl)carbene Complexes of Chromium and TungstenWe report on a three-step procedure for the regiospecific 2-oxybenzoanellation to cycloheptatriene by means of Fischer carbene complexes and alkynes. The first step involves the formation of (cycloheptatrienylmethyl)carbene complexes LnM=C(OEt)—CH2-c-C7H7 [1, LnM = Cr(CO)5 (a), W(CO)5 (b)] from the corresponding methylcarbene complexes and a tropylium salt. 1 reacts with the alkyne Et2N—C≡C—Me (2) to give the (E)- and (Z)-1-amino(1-alkenyl)carbene complexes LnM=C(NEt2)—C(Me)=C(OEt)—CH2—c-C7H7 (3 and 4 resp.). Thermolysis of 3b [LnM = W(CO)5, 100°C, 5 h] finally leads to elimination of W(CO)5(Et2NH) (6b) and the regiospecific formation of the ethoxybenzocycloheptatrienes 5,7, and 8 in 92% total yield. The reaction is kinetically controlled and yields an isomeric ratio of 5:7:8 = 60:12:20% with the thermodynamically less stable isomer 5 predominating.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921250812
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  • 6
    Electronic Resource
    Electronic Resource
    Organische Synthesen mit Übergangsmetall-Komplexen, 62. Erste Carbenkomplexe (M=Cr, W) mit Kohlenhydrat-Substituenten (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 2773-2778 
    Details
    ISSN: 0009-2940
    Keywords: Carbene complexes of carbohydrate derivatives ; Vinylcarbene chromium and tungsten complexes ; α-D-Mannofuranosides, 2,3:5,6-di-O-isopropylidene-, of carbene complexes ; α-D-Allofuranosides, 1,2:5,6-di-O-isopropylidene-, of carbene complexes ; α-D-Glucofuranosides, 1,2:5,6-di-O-isopropylidene-, of carbene complexes ; 1,2-Propadienyliden tungsten complex ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Organic Syntheses via Transition Metal Complexes, 62. - First Carbene Complexes (M=Cr, W) with Carbohydrate SubstituentsThe first examples of transition metal carbene complexes of carbohydrate derivatives are described: 1,2:5,6-Di-O-isopropyliden-α-D-glucofuranose (2a), 1,2:5,6-di-O-isopropylidene-α-D-allofuranose (2b), and 2,3:5,6-di-O-isopropyliden-α-D-mannofuranose (2c) add regiospecifically at C-3 of alkynylcarbene complexes LnM=C(OEt)-C≡CPh 1 [LnM=Cr(CO)5 (a), W(CO)5 (b)] to give vinylcarbene complexes LnM=C(OEt)-CH=C(Ph)-O(sugar) (E/Z)-3a-g in good to excellent yields. As a minor side reaction the alkynyl carbene complex (CO)5W=C(OEt)-C≡CPh (1b) isomerises to give the 1,2-propadienylidene complex (CO)5W=C=C=C(OEt)C6H5 (4b).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921251224
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  • 7
    Electronic Resource
    Electronic Resource
    Kondensation von Methylcarben-Komplexen mit Säureamiden: β-Alkoxyalkenyl- und β-Aminoalkenylcarben-Komplexe von Chrom und Wolfram - Konkurrenz von Kondensation und Insertion (1990)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 123 (1990), S. 611-620 
    Details
    ISSN: 0009-2940
    Keywords: Key Words: Aminoalkenylation of methylcarbene complexes / Carbon = carbon bond, formation by insertion into M = C bonds / Alkenylcarbene complexes, by condensation, by condensation, insertion / Carbene 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, 441. - Condensation of Methyl Carbene Complexes with Acid Amides: β-Alkoxyalkenyl- and β-Aminoalkenyl Carbene Complexes of Chromium and Tungsten - Competition of Condensation and InsertionThe condensation of the methyl(ethoxycarbene) complexes LnM = C(OEt)CH3 (4) [LnM = Cr(CO)5, W(CO)5] with acid amides RCONR1R2 (5) under the influence of POCl3/Et3N leads stereoselectively to (E)-β-aminoalkenyl(ethoxycarbene) complexes LnM=C(OEt)CH=C(R)NR1R2 [(E)-6] (R = H, aryl, alkyl). A condensation of 4 can also be achieved via amidium salts 11, which are easily available from 5. In this case, (E)-6 and (E)-β-alkoxyalkenyl(ethoxycarbene) complexes LnM=C(OEt)CH = C(R)OEt[(E)-13] were obtained. Via the cyclic amidium salts 15 and 20 four-to seven-membered lactams (E)-17 and (E)-21a-d are accessible. The reaction of 4 with acid amides RCH2CONR1R2 (2) and POCl3/Et3N yields mainly insertion products LnM=C(NR1R2)C(R)=C(OEt)CH3 [(E)/(Z)-22] and only small amounts of condensation products LnM=C(OEt)CH=C(CH2R)NR1R2 [(E)-23].
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19901230330
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  • 8
    Electronic Resource
    Electronic Resource
    Pyrrole durch metallinduzierte [3 + 2]-Cycloaddition von 2-Azaallenyl-( = Iminocarben-)Komplexen unter Übertragung einer CNC-Einheit auf ein Alkin; ein Chromacyclopropen durch Cyclocarbonylierung eines 1-Aminoalkins (1990)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 123 (1990), S. 599-604 
    Details
    ISSN: 0009-2940
    Keywords: 2-Azaalienyl chromium complexes / Pyrroles by [3+2] cycloadditions of CNC units / Umpolung of nitrile ylides, metal-induced / 1-Aminoalkynes, cyclocarbonylation / Chromacyclopropene ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Organic Syntheses via Transition Metal Complexes, 40. - Pyrroles by Metal-Induced [3 + 21 Cycloadditions of 2-Aza-allenyl (= Iminocarbene) Complexes with Transfer of a CNC Unit to Alkynes; a Chromacyclopropene Complex by Cyclocarbonylation of a 1-AminoalkyneThe 2-azaallenyl (= iminocarbene) complex LnM⊖ - CR = N⊕ = CXR1 1a [LnM = Cr(C0)5 = OEt, R1 = Ph] adds to the polarized alkyne Et2N - C≡C-CH3 (3) to give a 2H-pyrrole complex 4 in a metal-induced [3+2] cycloaddition. On warming 4 yields the 2H-Pyrrole 5. Since the regiochemistry of the addition of the CNC unit is opposite to that of a nitile ylide, we consider 1 as an Umpolung equivalent (RC⊕ = N - C⊖XR1) of a nitrile ylide (RC⊕ = N - C⊖XR1). The 2H-pyrrole 5 is kinetically unstable and isomerizes smoothly to the 1H-pyrrole 7 under the influence of base by an intramolecular redox reaction. A novel (cyclopentadienyl)chromacyclopropene complex 8 resulting from a cyclocarbonylation of the iminoalkyne 3 is obtained as a minor side product. The structural data of 4 and 8 have been determined by X-ray analyses.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19901230328
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  • 9
    Electronic Resource
    Electronic Resource
    Organische Synthesen mit Übergangsmetallkomplexen, 48. Methyl(thiocarben)- und Alkenyl(thiocarben)-Chrom-Komplexe: Darstellung und Reaktionen (1990)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 123 (1990), S. 2053-2058 
    Details
    ISSN: 0009-2940
    Keywords: Methyl thiocarbene chromium complexes, aldol condensation of ; Alkenyl thiocarbene chromium complexes, preparation of ; 1-Chroma-1,3-dienes, degradation on silica gel ; 1-Aza-1,2,4-pentatriene ; Thioenol ethers ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Organic Syntheses via Transition Metal Complexes, 48.  -  Methyl Thiocarbene and Alkenyl Thiocarbene Chromium Complexes: Synthesis and ReactionsThiocarbene chromium complexes (CO)5Cr=C(SR1)R (4: R = Me, Ph; R1 = c-C6H11, CH2CH=CH2, C2H5, C6H5) were readily obtained in up to 97% isolated yields from the corresponding ethoxycarbene chromium complexes 5a, b and thiols 6 in methanol in the presence of Na2CO3 as a catalyst. Reaction conditions, which lead to unfavorable side products, like thioacetals 8 and or thioenol ether 10, are discussed. Methyl thiocarbene complexes 4b-d undergo a facile aldol condensation with the aromatic aldehydes 14 or 16 to give alkenyl thiocarbene complexes 15b-d and 17, respectively. The Cr=C bonds of 15 prove to be reactive towards the insertion of isocyanides or oxygen. Thus, on addition of two equivalents of the isocyanide 18 to 15d, 1-aza-1,2,4-pentatriene 20 is obtained. The oxidative decomposition of 15d on silica gel leads to the formation of thioester 25 and thioindene 26. Characteristic differences in the reactivity of thiocarbene complexes and ethoxycarbene complexes are discussed.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19901231017
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  • 10
    Electronic Resource
    Electronic Resource
    Organische Synthesen mit übergangsmetall-Komplexen, 52 N-Vinylaminocarben- und N-(2-Propenyl)aminocarben-Komplexe durch Addition von Keteniminen an Carben-Eisenkomplexe (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1795-1803 
    Details
    ISSN: 0009-2940
    Keywords: Aminocarbene complexes of iron ; N-Vinylaminocarbene complexes ; π-Allyl,σ-complexes of iron ; N-(2-Propenyl)aminocarbene complexes ; Methylenation of ketene imines by carbene complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Organic Syntheses with Transition Metal Complexes, 52 1). - N-Vinylaminocarbene and N-(2-Propenyl)aminocarbene Complexes by Addition of Ketene Imines to Carbene Iron ComplexesKetene imines R(Me)C = C = NPh (2, R = Me, Et, i-Pr) form 1 : 1 adducts with the carbene iron complex (CO)4,Fe=C(OEt)Ph (1). The initial step of the reaction involves an attack of the nitrogen atom of 2 at the carbene carbon atom of 1 and a subsequent rearrangement to give N-vinylaminocarbene complexes (E/Z)-4. In a parallel process with different regiochemistry the central carbon of the CCN unit is attached to the carbene carbon to yield π-allyl,σ-complexes (E/Z)-3. Alkylation of 3a with [Et3O]BF4 leads to the formation of a cationic N-(2-propenyl)-aminocarbene complex 6a. Protonation of 4 with trifluoroacetic acid results in a ring contraction to give the four-membered metallacycles 7. X-ray data are reported for prototypes (Z)-4c and 6a.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19911240816
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