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  • 1
    Electronic Resource
    Electronic Resource
    P/O Ligand Systems: Synthesis, Reactivity, and Structure of Tertiary o-Phosphanylphenol Derivatives (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 431-431 
    Details
    ISSN: 0009-2940
    Keywords: o-Phosphanylphenols ; P,O hybrid ligands ; P asymmetry ; C,O-dilithium reagents ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300320
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  • 2
    Electronic Resource
    Electronic Resource
    P/O Ligand Systems: Facile Synthesis, Structure, and Catalytic Tests of 2′-Phosphanyl-1,1′ -phenyl-2-ols and 2′-Phosphanyl-1,1′-binaphthyl-2-ols (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1663-1670 
    Details
    ISSN: 0009-2940
    Keywords: Lithiation ; P ligands ; NMR spectroscopy ; Molecular structure ; Hydrogenations ; Hydroformylations ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A facile synthesis of 2′-phosphanyl-1,1′-biphenyl- and 2′-phosphanyl-1,1′ -binaphthyl-2-ols and their silyl ethers has been developed, consisting of electron-transfer-catalyzed ring-opening of dibenzofuran and dinaphthofuran, respectively, subsequent reaction with chlorophosphanes, and work-up with acetic acid or ClSiMe3. Studies of the molecular and crystal structures reveals the presence of P - H - O bridging bonds in the more basic tBuPhP derivative and a nearly perpendicular arrangement of the aryl planes in the biphenyl derivatives. The barrier to rotation of the aryl planes about the C-C axis was determined by NMR in the case of the P-asymmetric derivative 3d, using the appearence of diastereoisomers by atropisomerism and P-asymmetry. Comparative screening tests of the title compounds, phosphanyl phenols and phosphanylnaphthols in homogeneous Rh-catalyzed reactions demonstrate catalytic activity in hydroformylation reactions and superior properties of the biphenyl- and binaphthyl-2-ol derivatives in relation to other P-O ligands.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971301118
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  • 3
    Electronic Resource
    Electronic Resource
    Syntheses, Structures, and Reactivity of 1-Phosphanylnaphth-2-ols (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 1061-1071 
    Details
    ISSN: 0009-2940
    Keywords: Phosphanylnaphthol ; PO ligands ; Chelate complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: P-tertiary or amino-substituted 1-phosphanylnaphth-2-yl silyl ethers 3 are synthesized by stepwise reaction of lithium 1-lithio-2-naphtholate 1 with chlorophosphanes and ClSiMe3. The free phosphanylnaphthols 4 are prepared by alcoholysis. As established by characteristic coupling constants and X-ray structural analyses (of 3c, 4c), 3 exhibit in solution and in the solid state a cis-bisecting conformation, whereas 4 prefers the opposite trans-bisecting arrangement, allowing easy protonation and formation of chelate complexes. Substitution reactions of phosphanylnaphtholates 2 with Ph2PCl and formation of chelate complexes LNi-η5-Cp and L2Pd are described. Attempts to prepare secondary and primary phosphanylnaphthols failed because of facile cleavage of the P-C(naphthyl) bond in PH-substituted 1-phosphanylnaphth-2-ols.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19961290914
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  • 4
    Electronic Resource
    Electronic Resource
    Synthese, NMR-Spektren und Photoelektronen-Spektren von cyclischen Keten-N,X1-acetalen (2-Alkyliden-N-heterocyclen) (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 503-516 
    Details
    ISSN: 0009-2940
    Keywords: Ketene N,X1-acetals, cyclic ; Azolium salts, 2-alkyl-deprotonation of ; Imidazolidines, 2-alkylidene- ; Benzimidazoles, 2-alkylidenedihydro- ; Benzoxazoles, 2-alkylidenedihydro- ; Oxazolidines, 2-alkylidene ; Indoles, 2-alkylidenedihydro- ; Perimidines, 2-alkylidenedihydro- ; IGLO calculations ; 1,3-Dipolar cycloaddition reactivity and carbon-13 chemical shifts, correlation between ; Photoelectron spectra ; Electronic structures ; Calculations, AM1, MNDO, PM3 ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis, NMR Spectra, and Photoelectron Spectra of Cyclic Ketene N, X1-Acetals (2-Alkylidene-N-heterocycles)Deprotonation by sodium hydride of the N1-methyl-2-alkyl-azolium salts 10c, 14-16 and 18 and of the perimidinium salt 20 as well affords the corresponding ketene N,X1-acetals 1c, 3-5, 7, and 8 as air-sensitive distillable oils or low-melting crystals. The α1-carbon atoms of cyclic ketene N,X1-acetals resonate at very high field with the smallest chemical shift of no more than δ=39 for the 5-methylenedihydrotetrazol 2a. Geometries of 1a, b, 2a, and b were optimized on the Hartree-Fock level with polarized double-ζ basis sets, followed by IGLO calculations of the NMR chemical shifts. These are in excellent agreement with the unusual carbon-13 shifts observed. The electronic structures of 1a, b, 2a, b, 3a, b, 4b, 5b, 6a, and b are investigated by photoelectron spectroscopy and semi-empirical quantum chemical calculations. The observed ionization potentials are assigned to molecular orbitals on the basis of Koopmans' theorem. The order of reactivity in 1,3-dipolar cycloaddition reactions of cyclic ketene N,X1-acetals resembles that of the chemical shifts of their α1-carbon atoms.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931260230
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  • 5
    Electronic Resource
    Electronic Resource
    P/O Ligand Systems: Synthesis, Reactivity, and Structure of Tertiary o-Phosphanylphenol Derivatives (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 1547-1560 
    Details
    ISSN: 0009-2940
    Keywords: o-Phosphanylphenols ; P,O hybrid ligands ; P asymmetry ; C,O-dilithium reagents ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reactions of C,O-dilithium reagents 1 (M = M′ = Li) or C,O-lithium-sodium reagents 1 (M = Li, M′ = Na) with chlorophosphanes afford C,O-disubstitution products 2 or phosphanylphenolates 3 which are treated subsequently with ClSiMe3 to give 4-methyl- and bulky 4,6-di-tert-butyl substituted o-phosphanylphenol silyl ethers 4. These were applied for the preparation of the corresponding o-phosphanylphenols 5, mainly P-asymmetric derivatives. Limitations and side reactions by use of 1 in the above synthesis are discussed. Acid-base properties, pH-dependent solubility in water/hexane, and substitution reactions at oxygen and phosphorus of selected representatives of 5 are reported. An example for the separation of enantiomers by esterification with (1S)-(—)-camphanic acid chloride is given. IR studies revealed intramolecular P-H—O bonds and 2J(PC) the preferred trans arrangement of the phenoxy group in solution. In the solid state, inter- and intramolecular P-H—O bonds were detected by X-ray structure analysis. The trans arrangement of the phenoxy group is preserved. Because of steric hindrance, the O substituents are tilted towards the phosphorus atom and thus induce large through-space coupling constants. The P-Sn distance of 336.9 pm in the bulky substituted O—SnMe3 moiety 8h is however too large for the formation of genuine intramolecular coordination. The versatility of o-hydroxyarylphosphanes and objectives of further studies are shown by preliminary results on complex formation and applications of these phosphanes in catalysis.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19961291223
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