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  • 1
    Electronic Resource
    Electronic Resource
    Organische Synthesen mit Übergangsmetall-Komplexen, 54 Cyclopentadiene aus 1-Metalla-1,3-dienen und Alkinen durch Cyclisierung intermediärer 1-Metalla-1,3,5-triene (Metall = Wolfram) (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2343-2347 
    Details
    ISSN: 0009-2940
    Keywords: Cyclopentadienes, synthesis of ; [3 + 2] Cycloadditions of 1-metalla-1,3-dienes and alkynes ; 1-Metalla-1,3,5-trienes of tungsten, cyclization to cyclopentadiene complexes ; η1-Cyclopentadiene tungsten complexes ; Aminocarbene 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, 54.  -  Cyclopentadienes from 1-Metalla-1,3-dienes and Alkynes by Cyclization of Intermediate 1-Metalla-1,3,5-trienes (Metal = Tungsten)We report on first examples of the formation of cyclopentadienes from a 1-metalla-1,3-diene LnM=C-C=C [LnM = W(CO)5] and an alkyne in [3 + 2] cycloaddition multistep reactions. In a first step the alkyne Et2N-C=C-Me (2) adds to the 1-metalla-1,3-diene (CO)5W = C(OEt)-CH=CHPh (1b) to give 1-metalla-1,3,5-trienes (CO)5W=C(NEt2)-CMe=C(OEt)-CH=CHPh (3b) and (CO)5W=C(OEt)-CH=C(NEt2)-CMe=CHPh (4b). In a second step 3b cyclizes to thecyclopentadiene complex 5, which has an η1 ylide-type structure as established by an X-ray analysis. Hydrolysis of 5 leads to the formation of a 3-aminocyclopentenone 7. The 1-metalla-1,3,5-triene 4b yields a cyclopentadiene complex 8. In contrast to 5 the carbon skeleton of 8 has a connectivity different from that of the C3 unit of the 1-metalla-1,3-diene 1.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19911241030
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  • 2
    Electronic Resource
    Electronic Resource
    Organische Synthesen mit Übergangsmetall-Komplexen, 57. 4,5-Homotropilidene durch intramolekulare Cyclopropanierung von (Cycloheptatrienylmethyl)carbenchrom- oder -wolfram-Komplexen (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 259-264 
    Details
    ISSN: 0009-2940
    Keywords: (Cycloheptatrienylmethyl)carbene complexes ; 4,5-Homotropilidenes ; Cyclopropanation, intramolecular ; Carbene complexes ; Cope rearrangement, metal influence on ; Rhodium complexes ; Iron complexes ; Chromium complexes ; Tungsten complexes ; Calculations, AM1, MNDO, PM3 ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Organic Syntheses via Transition Metal Complexes, 57[1].  -  4,5-Homotropilidenes by Intramolecular Cyclopropanation of (Cycloheptatrienylmethyl)carbenechromium or -tungsten Complexes(Cycloheptatrienylmethyl)carbene complexes LnM=C(OEt)-CH2C7H7 [3: LnM=Cr(CO)5 (a), W(CO)5 (b)] are obtained in yields of 80% by the reaction of the corresponding methylcarbene complexes LnM=C(OEt)CH3 1 with tropylium tetrafluoroborate (2) in THF/Et3N. Alkylation of 3 with 2 gives [bis(cycloheptatrienyl)methyl]carbene complexes LnM=C(OEt)CH(C7H7)2 [4: LnM=Cr(CO)5 (a), W(CO)5 (b)]. Thermolysis of 3 leads to the formation of an equilibrium mixture of the 4,5-homotropilidenes 5 and 6. According to NMR measurements and AM1 calculations the formation of 6 is strongly favored. An equilibrium between 4,5-homotropilidene complexes is significantly different from that of the metal-free ligands. By the reaction of 5/6 with bis(ethylene)rhodium 1,3-pentanedionate (8) the complexes 9 and 10 of both 4,5-homotropilidenes 5 and 6 are obtained in a 1:3 ratio. The (1,5-diene)rhodium(I) complexes 9 and 10 are nonfluxional and configurationally moderately stable at 20°C. The reaction of 5/6 with Fe2(CO)9 gives the π-allyl,σ complexes 11 and 12 in a 10:3 ratio, both of which may be derived from the minor 4,5-homotropilidene isomer 5. In 11 a vinylcyclopropane unit of 5 serves as a four-electron donor for a Fe(CO)3 group. In 12 the 4,5-homotropilidene unit is coordinated as a six-electron donor to a Fe2(CO)6 unit.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921250141
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  • 3
    Electronic Resource
    Electronic Resource
    Organische Synthesen mit Übergangsmetall-Komplexen, 64[1]. 1,4-Diaminonaphthaline über Ketenimin-Komplexe aus (β-Aminovinylcarben)chrom-Komplexen und Isocyaniden (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 1867-1872 
    Details
    ISSN: 0009-2940
    Keywords: Aminobenzannulation with isocyanides ; 1,4-Diaminonaphthalines ; Alkynylcarbene complexes ; β-Aminovinylcarbene complexes ; Dienylketenimine complexes ; 4-Amino-1-chroma-1,3-dienes ; Chromium complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Organic Syntheses via Transition Metal Complexes, 64[1]. - 1,4-Diaminonaphthalines via Ketenimine Complexes from (β-Aminovinylcarbene)chromium Complexes and IsocyanidesThe thermal reaction of (dienylcarbene)chromium complexes (= 1-chroma-1,3,5-trienes) with isocyanides provides a mild and regiospecific access to aromatic amines. Thus, 1,4-diamino-2-ethoxynaphthalines 6a-d [1-NHc-C6H11; 4-NRR1 = NMe2 (a) (S)-2-hydroxymethylpyrrolidinyl (b) (1R,2S)-2-methylamino-1-phenyl-1-propanol (c), NtBuMe (d)] are obtained by the cyclization of (E)-(β-aminostyrylcarbene)chromium complexes (CO)5Cr=C(OEt)CH=C(NRR1)C6H5 [(E)-3a-d] with cyclohexyl isocyanide (4) at 90°C in 72-85%. The aminocarbene complexes (E)-3a-d are accessible with high stereoselectivity [〉95% (E) configuration] and chemical yields of 91-96% by the addition of secondary amines HNRR1 2a-d to the (1-alkoxy-3-phenylpropynylidene)chromium complex (CO)5Cr=C(OEt)C≡CC6H5 (1). 3 and 4 give initially mono- and bis(isocyanide) complexes, e.g. (E)-8a and (E)-9a, and subsequently dienylketenimine complexes by the insertion of 4 into the M=C bond of 3. Dienylketenimine complexes are key intermediates in the formation of 6.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931260818
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  • 4
    Electronic Resource
    Electronic Resource
    Organische Synthesen mit Übergangsmetallkomplexen, 69. [2-(Acylamino)ethenyl]ketenimine aus [2-(Acylamino)ethenyl]carben-Komplexen sowie deren Ringschluß-Metathese zu Pyrrolen oder deren Elektrocyclisierung zu 1,4-DiaminonaphthalinenHerrn Prof. Helmut Werner zum 60. Geburtstag gewidmet. (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 717-724 
    Details
    ISSN: 0009-2940
    Keywords: [2-(Acylamino)ethenyl]carbene complexes ; Aminocarbene complexes of chromium and tungsten ; Ketene imines, 2-(acylamino)ethenyl ; Pyrroles, synthesis by ring-closing metathesis ; 1,4-Diaminonaphthalenes, synthesis by electrocyclization ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Organic Syntheses via Transition Metal Complexes, 69[1].  -  2-(Acylamino)ethenyl Ketene Imines from [2-(Acylamino)ethenyl]carbene Complexes and their Ring-Closing Metathesis to Pyrroles or Electrocyclization to 1,4-DiaminonaphthalenesHerrn Prof. Helmut Werner zum 60. Geburtstag gewidmet.[2-(Acylamino)ethenyl]carbene complexes LnM = C(OEt) —CH=CPh—[N(COR)Ph] 5 [LnM = (CO)5Cr, (CO)5W; R = C6H5, pMeOC6H4, pNO2C6H4, OtBu] are obtained by N-acylation of [2-(amino)ethenyl]carbene complexes LnM=C (OEt)-CH=CPh(NHPh) (Z)-3 in 72-90% chemical yields with high stereoselectivity. The reaction of (Z) - or (E)-5 with two equivalents of isocyanides RNC 6 (R = cC6H11, tBu) at 20°C gives the isocyanide complexes LnM(RNC) 9 and the [2-(acylamino)ethenyl]ketene imines RN=C=C(OEt)—CH = CPh[N(COR)Ph] 8 (〉95% yields) with configurational retention at the C=C(N) bond. Thermolysis of (Z)-8 (20-80°C) provides an efficient route to pyrroles 11 (90-95%) by a ring-closing metathesis with elimination of isocyanates 10, while the thermolysis of (E)-8, e.g. (E)-8g, at 20°C leads to the formation of 1,4-diaminonaphthalenes, e.g. 12g (〉95% yield), by an electrocyclic ring closure.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270422
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  • 5
    Electronic Resource
    Electronic Resource
    Organic Syntheses via Transition Metal Complexes, 74[1] Novel Phosphonium Allenide and 2-Phosphanylethenyl Carbene Chromium and Tungsten Complexes (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 2475-2482 
    Details
    ISSN: 0009-2940
    Keywords: Vinylcarbene complexes ; Chromium complexes ; Tungsten complexes ; Phosphorus ylide complexes ; Alkynylcarbene complexes ; Allene complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Alkynylcarbene complexes (CO)5M≡C(OEt)-C≡C—R 1 (M = Cr, W; R = Ph, tBu, SiMe3) readily add tertiary phosphanes PPhR2′ 4 (R′ = Ph, Me) to form stable zwitterionic phosphonium allenide complexes (CO)5M--C(OEt) = C≡C(R)-P+PhR2′ 5. Complex 5a (M = Cr, R = R′ = Ph) was characterized by X-ray diffraction. The addition of secondary phosphanes PHR2 6 to 1 affords red (2-phosphanyl ethenyl)-carbene complexes (CO)5M≡C(OEt)-CH≡C(R)-PR2 (E)-8 (R = tBu, cC6H11, Ph) in 34-89% isolated yields. Dinuclear complexes (CO)5M≡C(OEt)-CH≡C(R)-P(R2)M(CO)5 (E)-9 are obtained as byproducts. Compounds (E)-8b (M = Cr, R = cC6H11) and (E)-9i (M = Cr, R = Ph) were characterized by X-ray analyses.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941271218
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