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  • 1975-1979  (11,437)
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  • 201
    Electronic Resource
    Electronic Resource
    The effect of changes in salt concentration and pH on the interaction between glycosaminoglycans and cationic polypeptides (1976)
    New York : Wiley-Blackwell
    Biopolymers 15 (1976), S. 1965-1977 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Circular dichroism (CD) spectroscopy has been used to investigate the effects of changes in salt concentration and pH on the interactions between basic polypeptides and connective tissue glycosaminoglycans in dilute aqueous solution. The polypeptides undergo conformation-directing interactions in the presence of glycosaminoglycans, which are subject to transitions as the ionic strength and pH are varied. For poly(L-lysine), the conformational change due to interaction breaks down as the ionic strength (monovalent ions) is increased. Based on the ionic strength at which disruption occurs, the glycosaminoglycans can be placed in order of increasing strength of interaction: chondroitin 6-sulfate, hyaluronic acid, chondroitin 4-sulfate, heparin, and dermatan sulfate. Prior to the conformational transition, scattering effects are observed, indicating the development of larger aggregates. Each glycosaminoglycan induces α-helicity for poly(L-arginine), which does not break down as the ionic strength is increased, indicating a stronger interaction for this polypeptide. The pH-induced transitions are in the pH range 2.5-3.8 and are probably related to deionization of carboxyl groups. For poly(L-lysine) the conformational effect is disrupted at low pH. For poly(L-arginine), the transitions are not complete, but appear to correspond to an increase in scattering.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1976.360151008
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  • 202
    Electronic Resource
    Electronic Resource
    Synthesis and characterization of an ionizable polyhexapeptide collagen model (1976)
    New York : Wiley-Blackwell
    Biopolymers 15 (1976), S. 2005-2024 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Poly(Lys(HBr)-Gly-Pro-Pro-Gly-Pro) has been synthesized and studied by circular dichroism (CD) spectroscopy. It is apparently the first polyhexapeptide collagen model reported with an ionizable side chain. The monomer (ε-(p-nitrobenzyloxycarbonyl)-Lys-Gly-Pro-Pro-Gly-Pro-p-nitrophenyl-ester) was prepared by a stepwise strategy employing active esters. Polymerization in N,N-dimethyl formamide, followed by removal of the Lys side chain protection with HBr/acetic acid, gave a polydisperse product. Fractionation was accomplished by gel filtration chromatography. The polydisperse material had a molecular weight (Mr = 5-17,000). High molecular weight fractions from triple helices under concentrated conditions at 2°C. The triple helical structure gives a CD pattern very similar to that of collagen and its triple helical analogs. However, unlike collagen, the polyhexapeptide undergoes spontaneous dissociation at temperatures substantially below the melting temperature from a triple helical form to single chains. This process is promoted at low concentrations, high temperature, neutral pH, and low molecular weight, and is apparently due, in large part, to unfavorable ionic side-chain interactions. In addition to this relatively slow “ionic” dissociation the triple helical polypeptide may be thermally dissociated in a manner similar to collagen. The thermal denaturation is a relatively fast process compared with ionic dissociation.A high molecular weight fraction (3 × Mr = 48,000) was found to melt at 42°C at neutral pH but increased to 54°C at pH 12 where the lysyl side chains are predominantly deprotonated. Furthermore, reconstitution of triple helices appeared to be more readily achieved at high pH. Thus it is concluded that ionic repulsion between side chains causes destabilization of the triple helix and hinders reconstitution.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1976.360151011
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  • 203
    Electronic Resource
    Electronic Resource
    Étude thermodynamique de la transition hélice-pelote statistique en solvants mixtes de différents esters de l'acide poly(L-glutamique) (1976)
    New York : Wiley-Blackwell
    Biopolymers 15 (1976), S. 2059-2079 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Helix-coil transition of poly(γ-methyl-L-glutamate), poly(γ-ethyl-L-glutamate), and poly(γ-benzyl-L-glutamate) has been studied in mixed solvents by calorimetry, polarimetry, and viscometry. The experimental data have allowed the evaluation of solvation enthalpy Δhb, equilibrium constant K for hydrogen bond formation between the active solvent component and CO and NH groups, and the cooperativity parameter σ. The conformational transition of polypeptides in solution in a mixed solvent containing enough active solvent to maintain the coiled conformation has been produced by dilution with the helix-supporting solvent for the measurements of enthalpy of transition Δhs. The average value for Δhs is 3550 ± 300 J/mol and is practically independent of the nature of the side chain for the dichloroacetic acid-ethylene dichloride solvent pair at 25°C. A noticeable concentration effect exists in the case of poly(γ-benzyl-L-glutamate). The helical conformation is less stable for poly(γ-ethyl-L-glutamate), and this is explained by a steric effect hindering the access of dichloroacetic acid to side chains. Constant K has been calculated using polarimetric data and also from values of Δhs obtained at different temperatures using the Bixon and Lifson theory on the one hand and that of Sayama and coworkers on the other hand. Values of σ for poly(γ-ethyl-L-glutamate) have been calculated according to both theories mentioned, and the results show that the two sets of values are quite similar. The constant σ depends on the nature of the active solvent, on temperature, and on the binary-solvent composition. These conclusions are confirmed by viscometric results. Values of Δhb calculated from constant K are 5230 J/mol when Bixon and Lifson theory is used and 5569 J/mol when the theory at Sayama and coworkers is used. In both cases the value for Δhb is much lower than that of an intramolecular hydrogen bond. Experimental results suggest that the solvation mechanism would proceed in a manner so that mechanisms described in both theories are involved.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1976.360151014
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  • 204
    Electronic Resource
    Electronic Resource
    Internationale Regeln für die chemische Nomenklatur und Terminologie. Bd. 1. Deutsche Ausgabe. Hrsg. vom Deutschen Zentralausschuß für Chemie. Verlag Chemie GmbH, Weinheim 1975. 1. Aufl., Loseblattwerk, Ringbuch, DM 58,- (1976)
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 10 (1976), S. 30-30 
    Details
    ISSN: 0009-2851
    Keywords: Chemistry ; Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ciuz.19760100105
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  • 205
    Electronic Resource
    Electronic Resource
    Die Silberfarbbleich - Farbphotographie (1976)
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 10 (1976), S. 131-138 
    Details
    ISSN: 0009-2851
    Keywords: Chemistry ; Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ciuz.19760100502
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  • 206
    Electronic Resource
    Electronic Resource
    Irreversible thermodynamic analysis of electrophoretic light scattering experiments (1976)
    New York : Wiley-Blackwell
    Biopolymers 15 (1976), S. 21-28 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A fluctuation theory for electrolyte solutions is developed based on the coupling between the equations of nonequilibrium thermodynamics and the Poisson equation. The resulting fluctuation theory is applied to the analysis of electrophoretic light scattering. It is shown that in a binary electrolyte solution (two ionic species), the Doppler shift is not determined by the electrical mobility of either ion, but depends instead on the rate of change of transference number with salt concentration. In addition the ionic relaxation time is shown to be proportional to the conductivity of the solution.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1976.360150104
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  • 207
    Electronic Resource
    Electronic Resource
    Binding of proflavin to T2L bacteriophage and its DNA (1976)
    New York : Wiley-Blackwell
    Biopolymers 15 (1976), S. 97-111 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We have measured the binding equilibria of proflavin to T2L bacteriophage, in both “slow” and “fast” sedimenting forms, and to free T2L DNA. Measurements were carried out by difference spectroscopy at 430 nm at temperatures from 13 to 43°C and at pH 5.6 and 7.6. We found no significant difference in the binding parameters of the two phage forms. Also, the fraction of nucleotides available as binding sites for proflavin was the same for both free and intraphage DNA. However, the binding constant is about an order of magnitude lower for encapsulated than for free T2L DNA, due to the decreased exothermicity of the binding reaction within the phage head.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1976.360150108
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  • 208
    Electronic Resource
    Electronic Resource
    Application of the nearest-neighbor ising model to the helix-coil transition of polypeptides in mixed organic solvents (1976)
    New York : Wiley-Blackwell
    Biopolymers 15 (1976), S. 113-129 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Using the formalism of nearest-neighbor Ising model and assuming that the allowed states for a monomeric unity of a polypeptide chain in solutions containing strong acids are E (helix), C (coil), and CS (solvent-bonded coil), the partition function of the system was deduced analytically. Equations were obtained which permitted the prediction of the characteristic thermodynamic behavior of the helix-coil transition under these conditions. These equations were used to examine critically the possible correlations between experimental data obtained using different techniques. Particular attention was devoted to quantities called “transition enthalpies,” obtained from the slope of the transition curves at the point where the helix fraction is one-half (ΔHoptexp), or for measurements of the heat of solution of the polymer over the total range of solvent composition (ΔHsolexp), or from heat capacity measurements taken at various temperatures (ΔHcalexp). Literature data of ΔHjexp(j = opt, sol, cal) for the system poly-γ-benzyl-L-glutamate in mixtures of dichloroacetic acid and 1,2-dichloroethane were carefully analyzed.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1976.360150109
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  • 209
    Electronic Resource
    Electronic Resource
    Kinetic study of cooperative binding reaction of toluidine blue to poly(α,L-glutamic acid) by means of the electric-field pulse method (1976)
    New York : Wiley-Blackwell
    Biopolymers 15 (1976), S. 187-201 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Interaction of toluidine blue with helical and randomly coiled poly(α,L-glutamic acid) was studied with absorption spectra, titration, and electric-field pulse measurements. The obtained values of various parameters for the helical form of poly(α,L-glutamic acid)differed from those for its coiled form. The difference of parameters in these two forms of poly(α,L-glutamic acid) was attributed to differences of the binding mechanism in both forms. Furthermore, the binding of toluidine blue to poly(α,L-glutamic acid) was considered to be due to hydrogen binding in the helical conformation and ionic interaction in the coiled conformation of the polymer.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1976.360150113
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  • 210
    Electronic Resource
    Electronic Resource
    Cu(II) ions-DNA interaction: A dilatometric study (1976)
    New York : Wiley-Blackwell
    Biopolymers 15 (1976), S. 227-228 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1976.360150116
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  • 211
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    Electronic Resource
    Analysis of derivative binding isotherms. Theoretical considerationsPreliminary reports of this paper were presented at the Annual Meeting of the French Chemical Society, May, 1973, and the 26th Annual American Calorimetry Conference, Worcester, Mass, June, 1973. (1976)
    New York : Wiley-Blackwell
    Biopolymers 15 (1976), S. 337-354 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The basic theoretical groundwork for the use of derivative binding isotherms in the analysis of ligand binding is presented. The derivative binding isotherm is defined as Γ (Y) = df/dy where f = fractional degree of saturation and y = natural logarithm of the free ligand concentration. Since Γ (y) is a positive function, which goes to zero as y → ±∞, the mean value of y, 〈y〉, and the second and third moments, μ2 and μ3 about 〈y〉 are well defined.For a macromolecular system consisting of N equivalent and independent binding sites, Γ (y) is a symmetrical bell-shaped function with one maximum. The maximum occurs when y = -ln Kassoc; μ2 = π2/3, and μ3 = 0. For multiple sets of independent binding sites, Γ (y) is a superposition of Γ-type functions. If the sets are sufficiently well separated in binding free energy, multiple extrema may be seen at positions corresponding to the logarithms of the dissociation constants for the individual sets. In any case, 〈y〉 is equal to the mean value of the logarithms of the dissociation constants for the sets; μ2 〉 π2/3 and equal to π2/3 plus the variance of the logarithms of the dissociation constants about their mean value; and μ3 is, except by coincidence, not equal to zero and equals the third moment of the distribution of logarithms of the dissociation constants about their mean value.Analysis of Γ(y) for the case of cooperative interactions within a set of binding sites was investigated by examining (1) the Hill model (whose mathematical representation is equivalent to that used to describe antibody heterogeneity except that in the latter case the parameter a, the Sips, constant, is constrained (0 〈 a ≤1);(2) a common model for cooperativity in which the cooperative free energy is a linear function of the fraction bound; and (3) a general representation of cooperative interactions within a set of sites in terms of φ(f), a smooth function that gives the interaction free energy in units of RT.For the Hill model (or Sips model) Γ(y) is a symmetrical function with one maximum at y = (-1)/a)lnK, μ2 = π2/3a2; and μ3 = 0. For the case in which the cooperative free energy is a linear function of f [φ(f) = cf], 〈y〉 = -ln K0 + (c/2); μ2 = (π2/3) + c[(c/12) + 1] where c 〉 -4; and μ3 = 0. General expressions for the moments in terms of φ(f) are derived. In general, μ2 〈 (π2/3) for positive cooperativity and μ2 〉 (π2/3) for negative for negative cooperativity. Γ(y) will be symmetrical if and only if the cooperative free energy is introduced symmetrically about f = 0.5.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1976.360150211
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  • 212
    Electronic Resource
    Electronic Resource
    Specific heat thermal variations of L-valine and poly(L-valine) (1976)
    New York : Wiley-Blackwell
    Biopolymers 15 (1976), S. 415-418 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1976.360150217
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  • 213
    Electronic Resource
    Electronic Resource
    Structural investigations on DNA·protamine complexes (1976)
    New York : Wiley-Blackwell
    Biopolymers 15 (1976), S. 687-706 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Protamine·DNA complexes in film and in solution have been investigated by means of infrared linear dichroism, ultraviolet circular dichroism, and laser Raman spectroscopy. At high relative humidity and in solution both infrared linear dichroism and ultraviolet circular dichroism indicate the presence of a modified B form of DNA (designated as B* in our other papers27,28,46). This modified B form is characterized by a change of the orientation of the \documentclass{article}\pagestyle{empty}\begin{document}$ \widehat{OPO} $\end{document} bisector angle by about 4° with respect to the helical axis when compared to the B form of DNA. At decreasing relative humidities the same modified B form is maintained and no structural transitions B → A (or B → C) normally occurring in free DNA were observed. The absence of the A form in these complexes was also confirmed by laser Raman scattering studies of protamine·DNA complexes. On the basis of these results, a model of the protamine·DNA complex is proposed, which suggests that the presence of apolar amino-acid residues, and probably the folding of the polypeptide chain, is responsible for preventing the B-to-A transition; this occurs either by protecting the high-humidity modified B form against dehydration or by steric interference of this protein probably located in one of the DNA grooves.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1976.360150408
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  • 214
    Electronic Resource
    Electronic Resource
    Changes in the ultraviolet absorption of E. coli rRNA on ribosome unfolding (1976)
    New York : Wiley-Blackwell
    Biopolymers 15 (1976), S. 1229-1232 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1976.360150615
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  • 215
    Electronic Resource
    Electronic Resource
    Masthead (1976)
    New York : Wiley-Blackwell
    Biopolymers 15 (1976) 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1976.360150701
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  • 216
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    Proton and phosphorus-31 magnetic relaxation studies on the interaction of polyriboadenylic acid with Mn2+ (1976)
    New York : Wiley-Blackwell
    Biopolymers 15 (1976), S. 1315-1331 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Proton and phosphorus-31 nuclear spin-lattice relaxation times T1 and spin-spin relaxation times T2 have been measured on the single-stranded polyriboadenylic acid [poly(A)]-Mn2+ system in a neutral D2O solution in the temperature range 10°-90°C at 100 and 40.5 MHz, respectively, with the Fourier transform nmr method. Minimum values of T1 have been found for all these nuclei, which have enabled the exact estimation of apparent distances from Mn2+ to H2, H8, H1′, and the phosphorus nucleus to be 4.7, 4.1, 5.2, and 3.0 Å, respectively. The electron spin of Mn2+ penetrates into the phosphorus nucleus, giving 31P hyperfine coupling of more than 106 Hz. Evidence of penetration of the electron spin into H8 and H2 is also obtained, suggesting direct coordination of nitrogen atoms of the adenine ring to the Mn2+ Ion. Combined with the result from proton relaxation enhancement of water, it is concluded that every Mn2+ ion added is bound directly to two phosphate groups with a Mn2+-phosphorus distance of 3.3 Å, while a part of the Mn2+ ions are simultaneouly bound to the adenine ring. It is estimated that 39 ± 13% and 13 ± 5% of Mn2+ are coordinated by N7 and N3 (or N1), respectively. The motional freedom of poly(A) in the environment of the Mn2+ binding site has been found to be quenched to the extent that the rotational motion becomes several times slower than that of the corresponding Mn2+-free poly(A). The activation energies for the molecular motion are, however, practically unchanged from those for Mn2+-free poly(A), and are found to be 8.3, 8.5, 6.1, and 8.7 kcal/mol for H8, H2, H1′, and phosphorus, respectively. T2 of phosphorus is determined by the dissociation rate (k-1) of Mn2+ from the phosphate group for the whole temperature range studied with activation enthalpy of 6.5 kcal/mol. The dissociation rates of Mn2+ from the adenine ring are also estimated from proton T2 values below 50°C.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1976.360150708
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  • 217
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    Electronic Resource
    Masthead (1976)
    New York : Wiley-Blackwell
    Biopolymers 15 (1976) 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1976.360150801
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  • 218
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    The A and B conformations of DNA and RNA subunits. Potential energy calculations for dGpdC (1976)
    New York : Wiley-Blackwell
    Biopolymers 15 (1976), S. 1437-1437 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1976.360150716
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  • 219
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    Na+ effects on transitions of DNA and polynucleotides of variable linear charge density (1976)
    New York : Wiley-Blackwell
    Biopolymers 15 (1976), S. 893-915 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A range of linear charge densities of the ordered and disordered forms of DNA or polynucleotides can be obtained experimentally by acid or alkaline titration, or by the investigation of unusual complexes involving protonated bases or three-stranded helices. The variation of melting temperatures with Na+ concentration for various of these systems is known and in some cases is complemented by structural and thermodynamic information. We have extended the condensation-screening theory of Manning [Biopolymers, 11, 937-955 (1972)] to these systems. The stabilizing and destabilizing effects of Na+ (condensation and screening, respectively) and be independently varied, and the theory is successful in predicting the qualitative (in some cases, quanittative) behaviour that is observed. Comparison of theory and experiment indicates that the axial phosphate distance b for single-stranded polynucleotides increases with increasing pH. Values of the critical parameter ξ are obtained for the various polynucleotide structures. These values are essential for an understanding of ionic effects on charged ligand-polynucleotide interactions.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1976.360150507
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  • 220
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    Conformational energy calculations for dinucleotide molecules. A systematic study of dinucleotide conformation, with application to diadenosine pyrophosphate (1976)
    New York : Wiley-Blackwell
    Biopolymers 15 (1976), S. 955-975 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A systematic study of the conformational states of the dinucleotide diadenosine 5′,5′-pyrophosphate (AppA), an analog of the coenzyme NAD+, has been made using semi-empirical energy calculations. Taking low-energy mononucleotide structures as starting conformations, energy minimizations have been performed. The most stable structures exhibit stacking interactions between the adenine bases; there are many different stacked states of similar energy; their stability is derived from nonbonded interactions primarily between the bases but also from base-sugar interactions. The most common form of stacking in the most stable structures was found to be antiparallel A-A helix. These findings are consistent with the experimental data, which suggest that AppA adopts predominantly a stacked state in solution, and this state incorporates a variety of stacked conformations.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1976.360150511
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  • 221
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    Enhanced helicity of poly(α-L-glutamic acid) in aqueous tetraalkylammonium chloride (1976)
    New York : Wiley-Blackwell
    Biopolymers 15 (1976), S. 1005-1007 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1976.360150515
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  • 222
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    Electronic Resource
    Polynucleotide models. A correlation between helical parameters and the radial position of the backbone (1976)
    New York : Wiley-Blackwell
    Biopolymers 15 (1976), S. 1015-1018 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Tab.
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    URL: http://dx.doi.org/10.1002/bip.1976.360150517
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    The use of moment index displacement in analyzing fluorescence time-decay data (1976)
    New York : Wiley-Blackwell
    Biopolymers 15 (1976), S. 1093-1101 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Moment index displacement automatically corrects a number of significant nonrandom instrumental errors in fluorescence time-decay measurements. Three-component data, obtained by measuring the fluorescence decay of three different species mixed in the same solution, were used as a test sample. It was shown, as predicted by theory, that moment index displacement corrects three nonrandom instrumental errors: (1) the presence of scatter in the data; (2) time origin shifts between lamp and fluorescence data; and (3) lamp drift, or time-dependent changes in the shape of the excitation curve. The data clearly show that the use of the method of moments with moment index displacement to analyze fluorescence decay data is not a curve-fitting procedure. This procedure will accurately obtain decay parameters for multiple-exponential decays from certain badly distorted data, yielding a calculated curve very different from the actual data.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/bip.1976.360150606
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  • 224
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    Interaction of water with poly-α-amino acids. I. Relationships between conformation and relaxation processes (1976)
    New York : Wiley-Blackwell
    Biopolymers 15 (1976), S. 1155-1165 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The relaxation behaviour of the sodium salt of poly (L-glutamic acid) in the solid state has been examined by means of dynamic mechanical spectroscopy. Bound water was found to exert a profound influence on the relaxation behaviour and on a bulk property, the rigidity. Certain features of the loss spectrum have been identified with the hydration-dependent β-to-α conformational transition. Thus two side-chain relaxations are observed below ambient temperature, one associated with the β from (β1β) and a second at a lower temperature associated with the α form (β1α). The greater rigidity of the α form below the relaxation temperature and the larger rigidity drop accompanying the β1α can be explained in terms of the structural differences of the two conformations.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/bip.1976.360150611
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  • 225
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    Ultracentrifugal compression of gels (1976)
    New York : Wiley-Blackwell
    Biopolymers 15 (1976), S. 1243-1250 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: It has been observed that the amount of water associated with casein micelles is markedly higher when measured by intrinsic viscosity than by water content of the pelleted casein. A possible explanation of this discrepancy is that water is squeezed out of the pellet by the ultracentrifugal field. We have calculated the potential magnitude of this effect by considering a simple model system: an elastic gel swollen by solvent and compressed by the centrifugal field. Equilibrium is reached when the sum of the ultracentrifugal, elastic, and mixing free energies is a minimum. The equilibrium degree of swelling is calculated as a function of rotor speed, thickness of the unsolvated gel material, and enthalpy of mixing of solvent and solute. Sizable compressions can occur for highly swollen gels, if the enthalpy of mixing is moderately positive. Casein micelles from intrinsic viscosity measurements have a “hydration” of about 3.7 g water/g protein, corresponding to a swelling ratio of 6.3 relative to the dry protein. The observed pellet hydration is 1.9 g/g. Under the conditions of the experiment, pelleting at 25,000 rpm is predicted to decrease the swelling ratio to 4.9, and the hydration to 2.7 g/g, about half the observed decrease, if the enthalpy of mixing is 0.5 RT/mol segment. These calculations may be relevent to the deterination by pelleting of the solvent content of other biopolymer gels.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/bip.1976.360150703
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  • 226
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    Fluctuations and mechanical strength of α-helices of polyglycine and poly(L-alanine) (1976)
    New York : Wiley-Blackwell
    Biopolymers 15 (1976), S. 2137-2153 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: By using the static correlations of fluctuations in the dihedral angles of the α-helices of polyglycine and poly(L-alanine) calculated previously, geometrical fluctuations of a section (consisting of up to 18 peptide units) of the α-helices of infinite length are calculated. These fluctuations are found to differ in some respects (e.g., the dependence of amplitudes on the length of section) from those of a circular rod made of homogeneous continuous material. However, the moduli of the mechanical strengths (tensile Young's modulus, bending Young's modulus, and the shear modulus) of a circular rod are calculated, whose geometrical fluctuations are approximately equal to the fluctuations of a section consisting of 18 peptide units. They are of the order of 1011 dyn/cm2. The tensile rigidity, flexural rigidity, and torsional rigidity are calculated to be 1.20 × 10-3 dyn, 2.46 × 10-19 dyn·cm2 and 1.79 × 10-19 dyn·cm2 for polyglycine, and 1.96 × 10-3 dyn, 4.05 × 10-19 dyn·cm2 and 3.28 × 10-19 dyn·cm2 for poly(L-alanine), respectively.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1976.360151104
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  • 227
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    Specificity in the interaction between poly(L-glutamate) and iron (III) complex ions in aqueous solution (1976)
    New York : Wiley-Blackwell
    Biopolymers 15 (1976), S. 2219-2226 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The binding process between sodium poly(L-glutamate) and trans-2,2′,2″,2‴-tetrapyridyl-Fe(III) complex ions in aqueous solution at pH around 7 has been studied by means of equilibrium dialysis and optical measurements. The binding isotherm indicates the occurrence of a cooperative process, whereby bound molecules facilitate the association of additional molecules. According to circular dichroism (CD) data, this effect is coupled with that which sees a conformational change in the charged polypeptide upon progessive binding of complex counterions. All these features are discussed in the light of the structural characteristics of the interacting species. A stereochemical model of the association “complex” is proposed.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1976.360151109
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  • 228
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    Ferric complexes of acetoacetyl derivatives of poly(L-lysine), poly(L-ornithine), and poly(L-diaminobutyric acid). II. Conformational properties in solution. Evidence for a stereospecific complex formation (1976)
    New York : Wiley-Blackwell
    Biopolymers 15 (1976), S. 2255-2262 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The conformational properties of ferric complexes of poly(Nε-acetoacetyl-L-lysine), poly(Nδ-acetoacetyl-L-ornithine), and poly(Nγ-acetoacetyl-L-diaminobutyric acid) were investigated in 1:1 water/dioxane by CD techniques. Optical activity was found in the visible and in the uv absorption region of the polymeric complexes. The conformation of the peptide backbone was always that of a right-handed α-helix, and was found independent of the degree of complexation, at least up to a degree of binding of 20%. In the absorption region of the side-chain chromophores the optical activity is substantially affected by complex formation. In all three cases a splitting of the ligand π → π* transition centered at 257 nm is observed. These data suggest a stereospecific complex formation. From the signs of the splitting it also appears that the chirality of the poly(Nδ-acetoacetyl-L-ornithine) complex is opposite that of the other two polymers.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/bip.1976.360151112
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  • 229
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    Masthead (1976)
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 10 (1976) 
    Details
    ISSN: 0009-2851
    Keywords: Chemistry ; Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ciuz.19760100101
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  • 230
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    Chronik (1976)
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 10 (1976), S. 31-32 
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    ISSN: 0009-2851
    Keywords: Chemistry ; Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ciuz.19760100108
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  • 231
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    mini-chiuz (1976)
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 10 (1976), S. A4 
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    ISSN: 0009-2851
    Keywords: Chemistry ; Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ciuz.19760100109
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  • 232
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    Das Portrait: Peter Griess (1829-1888) (1976)
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 10 (1976), S. 42-47 
    Details
    ISSN: 0009-2851
    Keywords: Chemistry ; Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ciuz.19760100203
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  • 233
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    Lehrprogramm Stereochemie. Taschentext 39. Von F. D. Gunstone. Verlag Chemie GmbH, Weinheim 1975. 1. Aufl., VIII, 130 S zahlr. Formeln, brosch. DM 14,80 (1976)
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 10 (1976), S. 63-63 
    Details
    ISSN: 0009-2851
    Keywords: Chemistry ; Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ciuz.19760100208
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  • 234
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    mini-chiuz (1976)
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 10 (1976), S. A14 
    Details
    ISSN: 0009-2851
    Keywords: Chemistry ; Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ciuz.19760100210
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  • 235
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    Chemisch induzierte dynamische Kernspin-Polarisation (CIDNP) (1976)
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 10 (1976), S. 84-93 
    Details
    ISSN: 0009-2851
    Keywords: Chemistry ; Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ciuz.19760100304
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  • 236
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    Raketentreibstoffe (1976)
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 10 (1976), S. 97-105 
    Details
    ISSN: 0009-2851
    Keywords: Chemistry ; Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ciuz.19760100402
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  • 237
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    Masthead (1976)
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 10 (1976) 
    Details
    ISSN: 0009-2851
    Keywords: Chemistry ; Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ciuz.19760100301
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  • 238
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    Das Portrait: Adolf Windaus 1876-1959 (1976)
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 10 (1976), S. 175-179 
    Details
    ISSN: 0009-2851
    Keywords: Chemistry ; Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ciuz.19760100603
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  • 239
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    Chronik (1976)
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 10 (1976), S. 196-196 
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    ISSN: 0009-2851
    Keywords: Chemistry ; Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ciuz.19760100606
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  • 240
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    Einführung in die Physikalische Chemie (5 Teile) Von H. Labhart. Springer-Verlag, Berlin, Heidelberg, New York 1975; Teil I: Chemische Thermodynamik, XII, 167 S., 38 Abb., DM 16, -; Teil II: Kinetik, X, 105 S., 23 Abb., DM 13,60; Teil III: Molekülstatistik, XI, 126 S., 19 Abb., DM 14,-; Teil IV: Molekülbau, X, 171 S., 45 Abb., DM 16,-; Teil V: Molekülspektroskopie, X, 138 S., 52 Abb., DM 14,-; DM 14,-, kartoniert (1976)
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 10 (1976), S. 159-160 
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    ISSN: 0009-2851
    Keywords: Chemistry ; Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ciuz.19760100507
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  • 241
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    Cephalosporine (1976)
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 10 (1976), S. 189-195 
    Details
    ISSN: 0009-2851
    Keywords: Chemistry ; Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ciuz.19760100605
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  • 242
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    Die Vergasung von Kohle - Grundlagen und Anwendung (1976)
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 10 (1976), S. 11-20 
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    ISSN: 0009-2851
    Keywords: Chemistry ; Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Mikroskopische Aufnahme einer Gasflammkohle aus dem Ruhrrevier. Man erkennt, daß die Steinkohle uneinheitlich aus verschiedenen Gruppenbestandteilen zusammengesetzt ist, die man Macerale nennt. Je nach mikroskopischer Erscheinungsweise unterscheidet man drei Maceralgruppen: Vitrinit (graue Bereiche, z.B. links unten), Exinit (schwarze Bereiche, z.B. im Mittelteil des Bildes) und Inertinit (helle Bereiche, z.B. links oben). Vitrinit und Exinit sind die beiden reaktionsfähigen Maceralgruppen; der Inertinit ist stets reaktionsträge und daher schwerer chemisch umzuwandeln als Vitrinit und Exinit.
    Additional Material: 10 Ill.
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    URL: http://dx.doi.org/10.1002/ciuz.19760100103
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  • 243
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    Biochemie der Blutgerinnung und Fibrinolyse. Von Irene Witt. Verlag Chemie GmbH, Weinheim 1975. 1. Aufl., 150 S., 30 Abb., 14 Tab., geb. DM 42,- (1976)
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 10 (1976), S. 30-30 
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    ISSN: 0009-2851
    Keywords: Chemistry ; Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ciuz.19760100107
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  • 244
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    Die Biochemie der Schlangengifte (1976)
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 10 (1976), S. 33-41 
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    ISSN: 0009-2851
    Keywords: Chemistry ; Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ciuz.19760100202
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  • 245
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    Konformationsanalyse, XIII1) Umformung von 1,6-Anhydro-β-D-glucopyranose-Ringen in Bootkonformationen durch polare 1,3-diaxiale Wechselwirkungen. Synthese der 2,4-Diamino-1,6-anhydro-2,4-didesoxy-β-D-glucopyranose (1976)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 104-111 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Conformational Analysis, XIII1) Conversion of 1,6-Anhydro-β-D-glucopyranose Rings to Boat Conformations by Means of Polar 1,3-Diaxial Interactions Synthesis of 2,4-Diamino-1,6-anhydro-2,4-dideoxy-β-D-glucopyranoseTreatment of 1,6:3,4-dianhydro-2-O-p-tolylsulfonyl-β-D-galactopyranose (5) with hydrazine followed by hydrogenation leads to 2, 4-diamino-1,6-anhydro-2,4-dideoxy-β-D-glucopyranose (8) with 85% yield. 1,6-Anhydro-2, 4-diazido-2, 4-dideoxy-β-D-glucopyranose (10) is obtained by reaction of 5 with sodium azide. Strong 1,3-diaxial interaction causes twisting of the pyranose ring in the 2,4-diazido compound 10 into the 1S0-Skew form 20, in the diammonium compound 9 into the 1.4B boat form 21
    Notes: 1.6:3,4-Dianhydro-2-O-p-tolylsulfonyl-β-D-galactopyranose (5) ergibt mit Hydrazin und anschließender Hydrierung 2,4-Diamino-1, 6-anhydro-2,4-didesoxy-β-D-glucopyranose (8) zu 85%. Mit Natriumazid ist aus 5 1.6-Anhydro-2.4-diazido-2.4-didesoxy-β-D-glucopyranose (10) gewinnbar. Durch starke polare 1,3-diaxiale Wechselwirkung ist der Pyranosering in der 2,4-Diazido-Verbindung 10 zur 1S0-Skew-Form 20 in der Diammonium-Verbindung 9 zur1.4 B-Boot-Form 21 verdreht.
    Additional Material: 2 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19761090108
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    Darstellung und Eigenschaften von N3-(3-L-Amino-3-carboxypropyl)uridin-5′-monophosphat - einem modifizierten Nucleotid aus Transfer-RNA (1976)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 82-89 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Preparation and Properties of N3-(3-L-Amino-3-carboxypropyl)uridine 5′-Monophosphate--a Modified Nucleotide from Transfer RNAN3-(3-L-Amino-3-carboxypropyl)uridine-5-monophosphate (5b), an α-L-aminobutyrate-modified uridine 5′-monophosphate (UMP), which is found at position 47 in the extra loop of Escherichia coli tRNAphe, was prepared from N3-(3-L-amino-3-carboxypropyl)uridine (5a) by phosphoryl chloride phosphorylation. Also described are the experimental conditions for the preparation of nucleoside 5a which was obtained by alkylation of isopropylideneuridine with ethyl α-L-benzamido-γ-bromobutyrate and after removal of the protecting groups from the intermediate 4. Comparison of the c. d. Spectra of 5b and UMP shows that the modified nucleotide under alkaline conditions has a geometry different from that in neutral or acidic media. This pH-dependent change, which is not observed with UMP itself, may influence the 3-dimensional structure of tRNA.
    Notes: N3-(3-L-Amino-3-carboxypropyl)uridin-5′-monophosphat (5b), ein durch den α-L-Aminobuttersäurerest modifiziertes Uridin-5′-monophosphat (UMP), das im Extraloop der Escherichia coli tRNAphe Position 47 einnimmt, wurde aus N3-(3-L-Amino-3-carboxypropyl)uridin (5a) durch Phosphorylierung mit Phosphoroxychlorid gewonnen. Die experimentellen Bedingungen für die Darstellung des Nucleosids 5a, das durch Alkylierung von Isopropylidenuridin mit α-L-Benzamido-γ-brombuttersäure-äthylester nach Abspaltung der Schutzgruppen aus der Vorstufe 4 erhalten wurde, werden beschrieben. Der Vergleich der CD-Spektren von 5b und UMP zeigt, daß das modifizierte Nucleotid im alkalischen eine andere Geometrie als im neutralen oder sauren Medium besitzt. Diese pH-abhängige Änderung, die bei UMP nicht beobachtet wird, beeinflußt vermutlich auch die räumliche Struktur der tRNA.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19761090106
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    Die Molekül- und Kristallstruktur von C7H7RuC7H9 - (1-5-ν-cycloheptadienyl)(1-5-ν-cycloheptatrienyl)-ruthenium(II) (1976)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 125-131 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The Crystal and Molecular Structure of C7H7RuC7H9 - (1-5-ν- Cycloheptadienyl)(1-5-ν-cyclohepatrienyl)ruthenium(II)The structure of the title compound 5 has been determined by X-ray diffraction. The compound crystallizes in the space group P21/n, a = 644.2 ± 0.1 pm, b = 01775.8 ± 0.2 pm., c = 989.9 ± 0.1 pm, β = 97.72 ± 0.02°, Z = 4 (R = 0.035). The ruthenium atom is coordinated by a cyclohephtadienyl and cycloheptatrienyl ligand, both functioning as five electron ligands. One double bond of the cycloheptarienyl ligand does not interact with the central atom.
    Notes: Mittels Röntgenanalyse wurde die Struktur der Titelverbindung 5 bestimmt. Der Komplex kristallisiert in der Raumgruppe p21/n, a = 644 ±0.1pm, b = 1775.8 ± 0.2pm, c = 989 ± 0.1pm, β = 97.72 ± 0.02°, Z = 4 (R + 0.035). Das Ruthenium ist im Komplex jeweils von einem Cycloheptadienyl- und Cycloheptarienylliganden koordiniert. Beide fungieren als 5-Elektronenliganden, wobei im Cycloheptarienylligand eine Doppelbindung nicht in Wechselwirkung mit dem Zentralatom ist.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19761090111
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    Untersuchungen an Diazoverbindungen und Aziden, XXV1) Azid-Additionen an (Silyäthinyl)-, (Germyläthinyl)- und (Stannyläthinyl)amine (1976)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 370-394 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Investigations on Diazo Compounds and Azides, XXV1) Azide Additions on (Silylethynyl)-, (Germylethynyl)- and (Stannylethynyl)aminesThe lithium acetylides 1 react with trialkyl- and triphenylmetal halides 2 to form the (silylethynyl)-, (germylethynyl)-, and (stannylethynyl)amines 3. The ynamines add aryl-and sulfonyl azides to the 5-amino-1, 2,3-triazoles 4,5, and 7, which in the case of the sulfonyl azide adducts 5 and 7 isomerize largely to the diazoacetamidines 6 and 8, respectively. Water or deuterium oxide hydrolyze the carbon-metal bond of the diazo compounds 8 with formation of the [2-H1] - and [2-D1]diazoacetamidines 9 and 10.
    Notes: Durch Umsetzung von Lithiumacetyliden 1 mit Trialkyl- und Triphenylmetallhalogeniden 2 werden (Silyläthinyl)-, (Germyläthinyl)- und (Stannyläthinyl)amine 3 synthetisiert. Diese Inamine addieren Aryl- und Sulfonylazide zu den 5-Amino-1,2,3-triazolen 4,5 und 7, die im Falle der Sulfonyladdukte (5 und 7)weitgehend zu den Diazoacetamidinen 6 bzw. 8 isomerisieren. Die Diazoverbindungen 8 spalten den Metallrest bei Einwirkung von Wasser oder Deuteriumoxid leicht ab unter Bildung der [2-H1]- und der [2-D1]Diazoacetamidine 9 und 10.
    Additional Material: 9 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19761090139
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    Nucleosidtransformationen, 1. Umwandlung von Adenosin in 2′- und 3′-azido-, -amino- sowie -chlor-substituierte Desoxyadenosine1) (1976)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 433-443 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Nucleoside Transformations, 1 Transformation of Adenosine into 2′-and 3′-Azido, -Amino and -Chloro Substituted Deoxyadenosines1)Direct SN2-displacement of the 3′- or 2′-iodogroup in the iodohydrines 2b and 3b by chloride ions yields after removal of the protecting groups 3′-chloro-3′-deoxy- and 2′-chloro-2′-deoxyadenosine (4d and 5d). The 3′- and 2′-azidoadenosines 14b and 15b are obtained from the adenosinelyxoepoxide 11 with azide followed by inversion of configuration at the neighboring hydroxygroup. Their catalytical reduction yields the amines 16, 17.
    Notes: Direkte SN2-Substitution des 3′- oder 2′-Jodatoms in den Jodhydrinen 2b und 3b mit Chloridionen liefert nach Abspaltung der Schutzgruppen 3′-Chlor-3′-desoxy- bzw. 2′-Chlor-2′-desoxyadenosin (4d bzw. 5d). Die 3′- und 2′ -Azidoadenosine 14b, 15b, sind aus dem Adenosinlyxoepoxid 11 mit Azid und anschließende Konfigurationsumkehr an der benachbarten Hydroxylgruppe zugänglich. Ihre katalytische Reduktion ergibt die Amine 16, 17.
    Additional Material: 3 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19761090204
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  • 250
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    Synthese und Kristallstruktur eines zweikernigen Ylid-Komplexes mit Metall-Metall-Bindung zwischen Goldatomen der Oxidationsstufe + II1) (1976)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 466-472 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis and Crystal Structure of a Binuclear Ylide Complex with Metal-Metal Bonding between Gold Atoms in the Oxidation State + II1)The [diethylphosphoniumbis(methylido)]gold(I) dimer 4 reacts with one equivalent of chlorine, bromine, or iodine to give a series of compounds 5a-c, for which a bicyclic structure with a remarkably short transannular gold-gold bond (259.7 pm) is demonstrated by means of analytical and spectral data as well as by an X-ray analysis of 5a. The two metals of formal oxidation state +II are separated by a very short distance.
    Notes: Die aus dem [Diäthylphosphonium-bis(methylido)]gold(I)-Dimeren 4 und äquimolaren Mengen Chlor, Brom oder Jod erhältlichen Verbindungen 5a-c besitzen nach analytischen und spektroskopischen Daten sowie nach einer an 5a durchgeführten Röntgenstrukturanalyse eine bicyclische Struktur mit transannularer, auffallend kurzer Gold-Gold-Bindung (259.7 pm). Die nur durch einen sehr kurzen Abstand getrennten Metalle besitzen formal die Oxidationsstufe +II.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19761090208
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  • 251
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    Alkalische Carbonsäure-Eliminierung durch Nachbargruppeneffekt (1976)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 459-465 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Alkaline Carboxylic Acid Elimination by Neighbouring Group Participation3-(2-Hydroxy-3,4,5-trimethylphenyl)-3-methylphthalide (1) und 3-(2-Hydroxyphenyl)-3-methylphthalide (2) react in alkali by way of intramolecular carboxylic acid elimination to give the 1,1-diphenylethylenes 3 and 4 in high yields. It is shown that this elimination reaction dominates over the saponification of the lactone ring by the neighbouring group effect of the phenolate oxygen. Only with higher concentrations of hydroxylic ions the saponification reaction becomes faster in the case of 2. This neighbouring group effect, though in a slow reaction, Causes β-elimination of water in the tert. alcohols 11 c, e yielding the 1,1-diphenylethylenes 12c, e.
    Notes: 3-(2-Hydroxy-3,4,5-trimethylphenyl)-3-methylphthalid (1) und 3-(2-Hydroxyphenyl)-3-methylphthalid (2) geben in Alkali unter intramolekularer Carbonsäure-Eliminierung in hohen Ausbeuten die 1,1-Diphenyläthylene 3 bzw. 4. Es wird gezeigt, daß diese Eliminierungsreaktionen durch den Nachbargruppeneffekt des Phenolat-Sauerstoffes schneller ablaufen als die Verseifung der Lactonringe. Erst bei höheren Hydroxylionen-Konzentrationen wird im Falle von 2 die Verseifungsreaktion schneller. Dieser Nachbargruppeneffekt ermöglicht ferner - wenn auch in langsamer Reaktion - alkalische β-Eliminierung von Wasser aus den tert. Alkoholen 11c, e unter Bildung der 1,1-Diphenyläthylene 12c, e.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19761090207
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  • 252
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    2,4,6-Tribrom-1,3,5-tris(dibromboryl)borazin (1976)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 488-492 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: 2,4,6,-Tribromo-1,3,5-tris(dibromoboryl)borazineThe title compound can be obtained by the reaction of N-chlorovanadium nitride trichloride, Cl3 VNCl, with excess boron tribromide. The compound is characterized by its spectra.
    Notes: Die Titelverbindung 1 entsteht durch Umsetzung von N-Chlorvanadinnitridtrichlorid. CL3 VNCl, mit überschüssigem Bortribromid. Die Verbindung wird spektroskopisch charakterisiert.
    Additional Material: 1 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19761090211
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    Lichtinduzierte Reaktionen, X1) Die vier stereoisomeren 3,8-Diphenyl-1,2-diaza-1-cyclooctene (1976)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 518-530 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Light-Induced Reactions, X1) The Four Stereo Isomeric 3,8-Diphenyl-1,2-diaza-1-cyclooctenesThe complete set of configurationally isomeric 3,8-diphenyl-1-cyclooctenes covers species 1, 2, 3, and 4. The up to now unknown compounds (2 and 3) were prepared and identified, together with compound 4 hitherto thought to be 3. The configuration of 2 and 4 was unambigously determined by nonempirical n. m. r. analysis and X-ray diffraction, respectively; 1 and 3 are sufficiently characterized as photo isomers (with regard to orientation of ligands at the azo group) of 2 or 4.  -  The stereoisomeric 1,2-diaza-1-cyclooctenes 5 and 6 have been obtained in different ways and determined n. m. r. spectroscopically.
    Notes: Der vollständige Satz der konfigurationsisomeren 3,8-Diphenyl-1,2-diaza-1-cyclooctene umfaßt die Individuen 1, 2, 3, und 4. Die bislang unbekannten Verbindungen (2 und 3) wurden dargestellt und, zusammen mit der bisher als 3 angesehenen Verbindung 4, identifiziert. Die eindeutige stereochemische Zuordnung geschah bei 2 durch nichtempirische NMR-Analyse, bei 4 durch Röntgenstrukturanalyse; 1 oder 3 sind als Photo-Isomere (in bezug auf die Liganden an der Azogruppierung) von 2 oder 4 sicher charakterisiert. Die stereoisomeren 1,2-Diaza-1-cyclooctene 5 und 6 sind aud verschiedene Weise dargestellt und NMR-spektroskopisch bestimmt worden.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19761090215
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    Topographie der Cyclodextrin-Einschlußverbindungen, VIIVI. Mitteil.:W. Saenger, K. Beyer und P. C. Manor, Acta Crystallogr., im Durck (1975). Entnommen aus der Diplomarbeit M. Noltemeyer, Institut für Organische Chemie der Universität Göttingen und Max-Planck-Institut für Experimentalle Medizin, Göttingen 1974. Kurzmitteil.: W. Saenger und M. Noltemeyer, Angew. Chem. 86, 594 (1974). Angew. Chem., Int. Ed. Engl. 13, 552(1974).. Röntgenstrukturanalyse des α-Cyclodextrin. Krypton-Pentahydrats. Zum Einschlußmechanismus des Modell-Enzyms (1976)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 503-517 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Topography of Cyclodextrin Inclusion Complexes, VII* X-Ray Analysis of α-Cyclodextrin. Krypton Pentahydrate. On the Inclusion Mechanism of the Model EnzymeWhen crystallized from water under krypton pressures of 43 PSI (A) and 200 PSI(B), α-cyclodextrin (α-CD) yields inclusion compounds of composition α-CD·(0.78 H2O, 0.48 Kr)·5H2O (A) and α-CD·(0.28 H2O, 0.74 Kr)·5H2O (B). Both the adducts are isomorphous, space group P212121. The structures were determined from about 3900 X-ray data and refined to an R-factor of 8.8%. Although Kr has nearly the same van der Waals diameter as H2O (4Å), the structures of the Kr and of the recently determined α-CD·2H2O adduct are different. In the latter, the 5.0 Å wide cavity of α-CD is diminished by rotation of two glucoses, rendering the α-CD conformation strained. in the almost hexagonal Kr-adduct, all six glucoses are approximately equivalent, the cavity is 5 Å in diameter and the Kr is statistically disordered over five positions. It is concluded that α-CD adducts are stabilized through release of conformation- and hydrogen bonding energy when the “empty” α-CD·2H2O adduct transforms into any other adduct. This mechanism explains why so many different guest molecules are enclosed and bears some relation to enzyme-substrate interactions.
    Notes: α-Cyclodextrin (α-CD) liefert aus Wasser in Gegenwart von Krypton bei 3 und 14 atü kristalline Einschlußverbindungen der Zusammensetzung α-CD·(0.78H2O, 0.48 Kr)·5 H2O (A) und α CD·(0.28 H2O, 0.74 Kr)·5H2O (B). Beide sind isomorph, Raumgruppe P212121. Die Strukturen wurden aus etwa 3900 Röntgenreflexen gelöst und bis zu einem R-Faktor von 8.8% verfeinert. Obwohl Kr mit 4 Å van der Waals- Durchmesser etwa ebenso groß ist wie H2O3, sind die Strukturen der Kr-Addukte von der des reinen αCD·2H2O-Adduktes verschieden. Der 5.0 Å große Hohlraum im α-CD wird im H2O-Addukt durch Rotation zweier gegenüberliegender Glucosen zusammengezogen und dadurch gespannt. Im beinahe hexagonalen Kr-Addukt sind alle sechs Glucosen annähernd gleichwertig und das Kr besetzt statistisch fünf verschiedene Lagen, um den 5.0 Å weiten Innenraum auszufüllen. Es wird gefolgert, daß beim Austausch des Wassers gegen Gastmoleküle frei werdende Konformations- und Wasserstoffbrückenenergie die Addukte stabilisiert. Dieser Mechanismus erklärt, weshalb viele Gastmoleküle mit so unterschiedlichen Eigenschaften eingeschlossen werden und wird im Zusammenhang mit der Enzym-Substrat-Wechselwirkung diskutiert.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19761090214
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    Umsetzungen substituierter Aldehyde mit Diazoalkanen, IV1) Reaktionen von monosubstituierten Benzaldehyden mit Diazomethan (1976)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 640-649 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reactions of Substituted Aldehydes with Diazoalkanes, IV1) Reactions of Monosubstituted Benzaldehydes with DiazomethaneThe step by step reaction of 2 molequiv. of o-cyano- and o-chlorobenzaldehydes 1 with diazo-methane gives besides 7b the ketones 3a, b and the β-ketols 4a, b. Whereas 4a isomerizes to the chalcone 5, dehydration of 5b yields the chalcone 6b. The m-substituted benzaldehydes 13 and diazomethane in the ratio 2:1 furnish the ketones 14a, b, the epoxides 15a, b and the β-ketols 16a, b; the last-named are dehydrated with acetic anhydride to the chalcones 17a, b. The p-substituted benzaldehydes 21 and half a molequiv. of diazomethane yield predominantly the ketones 24a, b and the β-ketols 22a, b and also small amounts of oxirane 25a, homologous β-ketol 27b and p-cyanophenylacetone 26a. With equivalent amounts of diazomethane and of two different aldehydes (o,m,p-cyanobenzaldehydes, chloral and p-nitrobenzaldehyde) one gets the “mixed” β-ketols 9, 12, 19, 29 as well as the oxiranes 20, 30, the “homogeneous” β-ketols 4a, 11, 16a, 22a and other ketones.
    Notes: Durch stufenweise Umsetzung von 2 Moläquivv. o-Cyan- bzw. o-Chlorbenzaldehyd 1 mit Diazomethan entstehen neben 7b die Ketone 3a, b und die β-Ketole 4a, b. Während 4a zum Chalkon 5 isomerisiert, dehydratisiert 4b zum Chalkon 6b. Die meta-substituierten Benzaldehyde 13 geben mit Diazomethan im Molverhältnis 2:1 die Ketone 14a, b, die Epoxide 15a, b und die β-Ketole 16a, b; die letzteren werden mit Acetanhydrid zu den Chalkonen 17a, b dehydratisiert. Die para-substituierten Benzaldehyde 21 lieferten mit einem halben Moläquiv. Diazomethan überwiegend die Ketone 24a, b und β-Ketole 22a, b neben kleinen Mengen von Oxiran 25a, homologem β-Ketol 27b und p-Cyanphenylaceton 26a. Aus äquivalenten Mengen Diazomethan und den äquivalenten Mengen zweier verschiedener Aldehyde (o,m,p-Cyanbenzaldehyde und Chloral bzw. p-Nitrobenzaldehyd) erhält man die “gemischten” β-Ketole 9, 12, 19, 29 sowie die Oxirane 20, 30 neben den “einheitlichen” β-Ketolen 4a, 11, 16a, 22a und anderen Ketonen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19761090227
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    Über Derivate des Hydrazins, 51) Darstellung und einige Eigenschaften trimethylsilylierter,-germylierter sowie -stannylierter Tosylhydrazine (1976)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 710-722 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On Derivatives of Hydrazine, 51) Preparation and Some Properties of Trimethylsilylated, -germylated, and -stannylated TosylhydrazinesWith the exception of TosN2H(SnMe3)2, all tosylhydrazines TosN2Hm(E′Me3)n(E″Me3)0-(E‴Me3)p(E′, E″, E‴= So, Ge, Sn; m + n + o + p = 3) have been synthesized and characterized. These were prepared mostly by silylation, germylation, or stannylation of tosylhydrazine, TosN2H3, with chlorides Me3ECl or amines Me3ENR2, and, in a few cases, by tosylation of hydrazines N2H2(EMe3)2 and N2H2(EMe3)3 with tosyl chloride. Amines Me3ENR2 react with these newly synthesized tosylhydrazines by an exchange of hydrogen or of E′Me3 for EMe3. The hydrazides TosN2Li(SiMe3)(EMe3), obtained by the reaction of LiN(SiMe3)2 with TosN2Li(SiMe3)(EMe3) (E=Si, Ge) decompose on heating into TosLi and the azo-compounds Me3Si—N=N—EMe3.
    Notes: Mit Ausnahme von TosN2H(SnMe3)2 konnten alle Tosylhydrazine TosN2Hm(E′Me3)n(E″Me3)0-(E‴Me3)p(E′, E″, E‴=Si, Ge, Sn; m + n + o + p = 3) synthetisiert und charakterisiert werden. Ihre Darstellung erfolgte in den meisten Fällen durch Silylierung, Germylierung oder Stannylierung von Tosylhydrazin, TosN2H3, mit Chloriden Me3 ECl oder Aminen Me3ENR2, in einigen Fällen durch Tosylierung von Hydrazinen N2H2(EMe3)2 und N2H(EMe3)3 mit Tosylchlorid. Amine Me3ENR2 reagieren mit den neu dargestellten Verbindungen unter Austausch sowohl von Wasserstoff als auch von E′Me3 gegen EMe3. Die aus TosN2H)SiMe3)(EMe3) (E=Si, Ge) mittels LiN(SiMe3)2 erhältlichen Hydrazide TosN2Li(SiMe3)(EMe3) liefern bei höheren Temperaturen unter TosLi-Abspaltung die Azoverbindungen Me3Si—N=N—EMe3.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19761090233
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    Darstellung und physikalische Eigenschaften mesoionischer 1,3-Dithiolone1) (1976)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 740-752 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Preparation and Physical Properties of Mesoionic 1,3-Dithiolones1)1,3-Dithiolylium-4-olates 3a-1 are preparatively interesting mesoionic 6π Arenes. Their synthesis from the corresponding dithioester derivatives 1a-1 and their infrared, electronic, and mass spectra are described. 3a, b, and f possess as sydnone analogues compounds relatively high dipole moments of 5.00, 5.54, and 5.98 D, respectively.
    Notes: 1,3-Dithiolylium-4-olate 3a-1 sind präparativ interessante mesoionische 6π-Aromaten. Ihre Synthese aus den entsprechenden Dithiocarbonester-Derivaten 1a-1 sowie Infrarot-, Elektronen- und Massenspektren werden beschrieben. Als Sydnon-Analoga besitzen 3a, b und f relativ große elektrische Momente von 5.00, 5.54 bzw. 5.98 D.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19761090235
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    Zum Mechanismus der Reaktion von 1,6-Methano-[10]annulen mit Elektrophilen1) (1976)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 769-776 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On the Mechanism of the Reaction of 1,6-Methano-[10]annulene with Electrophiles1)Chlorosulfonyl isocyanate reacts with 1,6-methano-[10]annulene (1) to give only the substitution product 7; cycloaddtion products are not observed. The formation of the dibromo dichloro adduct 10 by bromination of 1 with Br2 in the presence of triethylbenzylammonium chloride as a competitive nucleophil provides evidence for a two-step addition via a cationic intermediate. Upon nitration of 1 with dinitrogen pentoxide at -110°C addition products are formed which can be characterized by n.m.r. spectroscopy. With collidine/nitronium trifluoromethanesulfonate, 1 is nitrated almost exclusively in the 2-position to form 5. With other nitration agents, however, mixtures of 5 and 6 are formed.
    Notes: Mit Chlorsulfonylisocyanat reagiert 1,6-Methano-[10]annulen (1) ausschließlich unter Bildung des Substitutionsproduktes 7; ein Cycloadditonsprodukt ist nicht nachzuweisen. Beweisend für eine zweistufige Additionsreaktion von Brom an 1 über kationische Zwischenverbindungen ist die Bildung des Dibrom-dichlor-Adduktes 10 in Gegenwart von Triäthylbenzylammoniumchlorid als Konkurrenznucleophil. Bei der Nitrierung von 1 mit Distickstoffpentoxid bei -110°C entstehen NMR-spektroskopisch nachweisbare Additionsprodukte. Mit Collidin/Nitronium-trifluormethansulfonat wird 1 nahezu ausschließlich in 2-Stellung nitriert, während mit anderen Nitrierungsagentien Gemische aus den Isomeren 5 und 6 entstehen.
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    URL: http://dx.doi.org/10.1002/cber.19761090238
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    Natürlich vorkommende Terpen-Derivate, LIV1) Neue Terpenaldehydester aus Peucedanum luxurians Tamamsch (1976)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 788-790 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Naturally Occurring Terpene Derivatives, LIV1) New Terpene Aldehyde Esters from Peucedanum luxurians TamamschThe roots of Peucedanum luxurians Tamamsch contain besides already known terpenes five new aldehydes with mixed ester groups (3, 6-8, 10 and 13. Their structures have been elucidated by spectroscopic methods.
    Notes: Die Wurzeln von Peucedanum luxurians Tamamsch enthalten neben bereits bekannten Terpenen fünf neue Aldehyde mit gemischten Estergruppen (3, 6-8, 10, und 13), deren Strukturen durch spektroskopische Methoden geklärt werden.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19761090240
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  • 260
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    Notiz zur Synthese des 1,4-Pentamethylen-Dewar-Benzols1, 2) (1976)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 793-795 
    Details
    ISSN: 0009-2940
    Keywords: 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.19761090242
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  • 261
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    Notiz über die Peptidsynthese mit Triphenylphosphin/Tetrachlorkohlenstoff als Kondensationsreagenz, II1) (1976)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 801-804 
    Details
    ISSN: 0009-2940
    Keywords: 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.19761090245
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  • 262
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    Natürlich vorkommende Terpen-Derivate, LVI: Neue Furanoeremophilane aus mexikanischen Senecio-Arten (1976)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 819-825 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Naturally Occuring Terpene Derivatives, LVI: New Furanoeremophilanes from Mexican Senecio SpeciesThe investigation of two Mexican Senecio species yields, besides known sesquiterpenes, several new ones, their constitutions being elucidated mainly by spectroscopic methods (2, 3, 6-9, 14-16, 21, 22).
    Notes: Die untersuchung von zwei mexikanischen Senecio-Arten ergibt neben bekannten Sesquiterpenen mehrere neue, deren Konstitutionen hauptsächlich durch spektroskopische methoden geklärt werden (2,3,6-9, 14-16, 21, 22).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19761090304
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  • 263
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    Ringöffnende Cycloadditionen, II: Reaktion von Heterocumulenen mit 5-Äthoxy-3-phenylimino-3H-1,2,4-dithiazol (1976)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 848-854 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Ring-cleaving Cycloadditions, II: Reaction of Heterocumulenes with 5-Ethoxy-3-phenylimino-3H-1,2,4-dithiazoleReaction of acyl and imidoyl isothiocyanates with 5-ethoxy-3-phenylimino-3H-1,2,4-dithiazole (2) led to opening of the heterocyclic ring and formation of cycloadducts of the 1,2,4-dithiazolidine series (4,5). The corresponding reaction with two alkyl isocyanates afforded 1,2,4-thiadiazolidines (8).
    Notes: Reaktion von Acyl-und Imidoyl-isothiocyanaten mit 5-Äthoxy-3-phenylimino-3H-1,2,4-dithiazol (2) ergab unter Ringöffnung Cycloaddukte der 1,2,4-Dithiazolidinreihe (4,5). Die entsprechende Umsetzung mit zwei Alkylisocyananten führte zu Derivaten des 1,2,4-Thiadiazolidins (8).
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19761090307
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  • 264
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    Beiträge zur Chemie des Bors, LXXIV: Stabilisierung von Diborylaminen: (Borolanylamino)borane und (Diazaborolidinylamino)borane (1976)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 884-895 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Contributions to the Chemistry of Boron, LXXIV: Stabilisation of Diborylamines: (Borolanylamino)boranes and (Diazaborolidinylamino) boranesThe thermal decomposition of diborylamines into a borane and a borazine derivative becomes considerably more difficult when the boron atoms of diborylamines are incorporated into a five-membered ring system. This type of diborylamines is represented by (1-borolanylamino)-boranes as well as by (1,3-dimethyl-1,3,2-diazaborolidin-2-Ylamino)boranes whose structure and bonding are discussed on the basis of spectroscopic data.
    Notes: Durch Einbau der Boratome eines Diborylamins in ein fünfgliedriges Ringsystem wird die thermische Zersetzung der Diborylamine in ein Boran-und ein Borazin-Derivat beträchtlich erschwert. (1-Borolanylamino)borane und (1,3-Dimethyl-1,3,2-diazaborolidin-2-ylamino)borane repräsentieren diese Diborylamin-Typen, deren Struktur und Bindungsverhältnisse aufgrund spektroskopischer Daten diskutiert werden.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19761090310
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  • 265
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    Synthesen biologisch wichtiger Kohlenhydrate, 3: Sehr einfache Synthese von DL-Amicetose (1976)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 896-900 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Syntheses of Biologically Important Carbohydrates, 3: Very Simple Synthesis of DL-AmicetoseSorbic acid (1) reacts with peracetic acid to form 4,5-epoxy-DL-threo-hex-2-enic acid (2). Ring fission yields 2,3,6-trideoxy-DL-erythro-hex-2-enoic acid (3) which after hydrogenation to 2,3,6-trideoxy hexonic acid 4 forms the amicetonolactone (5). Reduction of 5 by diisobutyl aluminium hydride gives an anomeric mixture of the furanoic and pyranoic antibiotic sugar DL-amicetose (2,3,6-trideoxy-erythro-hexose) (6).
    Notes: Sorbinsäure (1) reagiert mit Peressigsäure zur 4,5-Epoxy-DL-threo-hex-2-ensäure (2) Anm. b. d. Korr. (15. 1. 1975): Die Enantiomeren 2 lassen sich mit opt. akt. 1-Phenyläthylamin leicht trennen., die nach Ringöffnung zur 2,3,6-Tridesoxy-DL-erythro-hex-2-enonsäure (3) und Hydrierung zur 2,3,6-Tridesoxy-hexonsäure 4 das Amicetonsäurelacton (5) liefert. reduktion von 5 mit Diisobutylaluminiumhydrid führt zum Anomerengemisch des pyranoiden und furanoiden Antibiotikumzucker DL-Amicetose (2,3,6-Tridesoxy-erythro-hexose) (6).
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19761090311
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  • 266
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    Reaktionen an der α-Methylengruppe von (Glycinato)platin(II)-Chelat-Komplexen (1976)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 965-969 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reactions of the α-Methylene Group in (Glycinato)platinum(II) Chelate ComplexesThe reaction of the glycinato complex (n-Bu3P)Pt(Cl)NH2CH2CO2) (1)with aldehydes or alkylating agents (dimethyl sulfate, benzyl chloride) affords the chelate compounds 3-6 with substituted α-amino acids.
    Notes: Der Glycinato-Komplex (n-Bu3P)Pt(Cl)NH2CH2CO2) (1) setzt sich mit Aldehyden oder Alkylierungsmitteln (Dimethylsulfat, Benzylchlorid) zu entsprechenden Chelat-Verbindungen 3-6 mit Höheren α-Aminosäuren um.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19761090317
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  • 267
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    Alkylierungsreaktionen an Thioamiden, II. Untersuchungen zur E/Z-Isomerie und innermolekularen Beweglichkeit in Thioimidsäureestern (1976)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 922-946 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Alkylation reactions of Thioamides, II: Investigations of E/Z Isomerism and Intramolecular Mobility in ThioimidatesA Series of N-substituted thioimidates A was prepared and investigated by n. m. r. spectroscopy. It is shown by direct thermal stereomutation and dynamic n. m. r. spectroscopy that an inversion mechanism and an imine-enamine tautomerism are pathways of the E/Z isomerization in A (ΔG≠=51.5 to 92.9 kj/mol).
    Notes: Es wurde eine Anzahl N-substituierter Thioimidsäureester A dargestellt und NMR-spektroskopisch untersucht. Durch direkte thermische Isomerisierung und dynamische NMR-Messungen konnte nachgewiesen werden, daß der Inversionsmechanismus und die imin-Enamin-Tautomerie Wege der E/Z-Isomerisierung bei A(ΔG≠= 51.5 bis 92.9 kj/mol) darstellen.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19761090314
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  • 268
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    Selenoimidsäureester (1976)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 956-964 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: SelenoimidatesThe new selenoimidates 3a-f were prepared and compared with imidates and thioimidates concerning their E/Z isomerism and barriers to isomerization.
    Notes: Die neuen Selenoimidsäureester 3a-f wurden dargestellt und hinsichtlich ihrer E/z-Isomerie und Isomerisierungsbarrieren mit Imidsäure- und Thioimidsäureestern verglichen.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19761090316
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  • 269
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    Neue Übergangsmetallkomplexe mit Nuclein-Basen und Nucleosiden (1976)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 970-993 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: New Transition Metal Complexes with Nucleic Acid bases and NucleosidesThe isolation of carbonylmetal complexes W(CO)5L (1), [W(CO)5L]- (2), [Mo(CO)3enL]- (3), (π-CH3C5H4)Mn(CO)2L (4), Rh(CO)2(CI)L (5), (H)(CO)(PPh3)2L2 (6), M(CO)(PPh3)2L (M = Rh, Ir) (7,8) and of phosphine and amine containing monomeric and polynuclear palladium(II) and platinum(II) complexes (9-14 with various neutral and anionic nucleic acid bases and nucleosides L is reported. Using i. r. and 1H n. m. r. data a tentative assignment of the coordination sites of the ambidentate ligands is given. The reaction of 1,3,7,9-tetramethylxanthinium perchlorate with Hg11 acetate affords the C-8 mercurated complex 15.
    Notes: Die Darstellung von Carbonylmetallkomplexen W(CO)5L (1), [W(CO)5L]- (2), [Mo(CO)3enL] (3)-, (π-CH3C5H4)Mn(CO)2L (4), Rh(CO)2(Cl)L (5), Ir(H)(CO)(PPh3)2L2 (6), M(CO)(PPh3)2L (M = Rh, Ir) (7,8) und von phosphin- und amin-haltigen monomeren sowie mehrkernigen Palladium(II)-und Platin(II)-und Platin (II)-Komplexen (9-14) mit einer Reihe von neutralen und anionischen Purin und Pyrimidin-Basen und Nucleosiden L wird beschrieben. Mit Hilfe von IR- und 1H-NMR- Daten wird versucht, die Koordinationsstellen der ambidenten Nucleinbasen zu bestimmen. 1,3,7,9-Tetramethylxanthinium-perchlorat wird mit Quecksilber (II)-acetat am C-8 metalliert (15).
    Additional Material: 6 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19761090318
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  • 270
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    Sterische Wechselwirkungen im Innern cyclischer Verbindungen, XXIV: Konsequenzen beim Ersatz von CH2 durch Heteroatome in Ringverbindungen (1976)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 1002-1010 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Steric Interactions of Inner Atoms in Cyclic Compounds, XXIV: Consequences of Replacing CH2-Groups by Hetero Atoms in Ring CompoundsThe method described allows to estimate the size of the cavity in crown ether type molecules. Dynamic 1H n. m. r. studies of the crown ether systems 2b, 2 and 3b, 3 show that by replacement of CH2 bridge members throught —S— as a rule the ring inversion barrier (ΔGC≠ decreases. In the ring system 2 replacing one CH2-group by one oxygen atom leads to higher (ΔGC≠-values. Whereas in 3b γ the barrier also is higher compared with 3aγ, 3bβ exhibits a lower (ΔGC≠-value than 3aβ. An interpretation is given in terms of several partly compensating effects, e. g. the loss of space filling hydrogen atoms proceeding from oligomethylene to hetero atom containing bridges, and repulsive steric interaction between the intraanular substituent X and the heteroatoms in the bridge.
    Notes: Die beschriebene Methode erlaubt eine vergleichende Abschätzung der Hohlraumgröße von Kronenäthern. Durch untersuchung der neuen Cyclen 2b, 2c und 3b, 3c mittels dynamischer protonenresonanz wird gefunden, daß bei Ersatz eines CH2- Brückenglieds durch —S— die Ringinversionsbarriere (ΔGC≠) abfällt. Ersatz einer einzelnen CH2-Gruppe durch —O— (vgl. 2aα, 2bα erhöht die Ringinversionsschwelle. Einführung zweier durch eine Äthylenbrücke getrennte Äther-Sauerstoffatome hat für X = NO2 (in 3b) einen Anstieg, für X = Cl (in 3bβ) jedoch eine Abnahme von ΔGC≠ zur Folge, Zur Deutung werden verschiedene sich teilweise kompensierende Effekte herangezogen: Am wichtigsten erscheinen der Wegfall der Raumbeanspruchung der H-Atome beim Übergang zu den heteroatom-haltigen Ringen sowie abstoßende sterische Wechselwirkungen zwischen dem intraanularen Substituenten X und Heteroatomen in der Brücke.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19761090320
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  • 271
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    Synthese von 6-Fluorbenz[a]anthracen-Derivaten (1976)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 1038-1045 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis of 6-Fluorobenz[a]anthracene Derivatives6-Fluoro-(12 and 6-Fluoro-12-methylbenz[a]anthracene(11) are prepared in several steps starting with 2-bromo-3-fluoronaphthalene (1). 6-Fluorobenz[a]anthracen-127H)-one (8) predominantly occurs in the enol form 9. Efforts to synthesize 6-fluoro-7,12-dimethylbenz[a]anthracene (10) are described.
    Notes: Ausgehend von 2-Brom-3-fluornapthalin (1) werden über mehrere Stufen 6-Fluor-(12) und 6-Fluor-12-methylbenz[a]anthracen (11) dargestellt. 6-Fluorbenz[a]anthracen-12(7 H)-on (8) liegt vorwiegend in der Enolform 9 vor. Syntheseversuche für 6-Fluor-7,12-dimethylbenz[a]anthracen (10) werden beschrieben.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19761090324
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  • 272
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    Komplexchemie polyfunktioneller Liganden, XXXVI: Über Halogeno- und Pseudohalogeno-kobalt(I)-Komplexe des tritertiären Phosphins 1,1,1-Tris(diphenylphosphinomethyl)äthan (1976)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 1095-1105 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Complex Chemistry of Polyfunctional Ligands, XXXVI: About Halogeno- and Pseudohalogeno-cobalt(I) Complexes of the Tritertiary Phosphine 1,1,1-Tris(diphenylphosphinomethyl)ethane\documentclass{article}\pagestyle{empty}\begin{document}$ [\mathop {{\rm Co}}\limits^{ + {\rm I}} ({\rm CO})_2 ({\rm R}_2 {\rm PCH}_2)_3 {\rm CCH}_3][\mathop {{\rm Co}}\limits^{ - {\rm I}} ({\rm Co})_4] $\end{document} (R = C6H5) 2 reacts with the alkali metal halides and pseudohalides MX(M = Na, K; X = Cl, Br, J) on ultraviolet irradiation to give the monomeric, paramagnetic (μeff ≍ 3 B.M.), tetrahedral cobalt(I) complexes XCo(R2PCH2)3CCH33 With CO the halogeno-cobalt(I) complexes 3a-c) yield the ionic, diamagnetic dicarbonyl compounds [Co(CO)2(R2PCH2)3]X(X = Cl, Br, J) 5. On the other hand the pseudohalogeno-cobalt(I) complexes 3d,e give with CO the non-ionic complex Co(NCO)(CO)2(R2PCH2C(CH3)CH2PR2 6. The potentially tridentate ligand CH3C(CH2PR2)3 Serves in it as a bidentate monometallic ligand. The halogeno- and pseudohalogeno-cobalt(I) complexes 3 are very air-sensitive. The forming of O2-complexes from the pseudohalogeno-cobalt(I) compounds 3d, e in the solid state has been shown qualitatively by the infrared spectra. In solution these O2complexes decompose to phosphine oxide-containing products. With 9,10-phenanthrenequinone, Co(NCO)(R2PCH2)3CCH3 (3d) gives also an oxidative addition product, the Paramagnetic Co(NCO)(C14H8O2(R2PCH2)2-C(CH3) CH2PR2 8 (μeff 2.97 B.M.). The compounds were characterized by their infrared and far infrared spectra.
    Notes: \documentclass{article}\pagestyle{empty}\begin{document}$ [\mathop {{\rm Co}}\limits^{ + {\rm I}} ({\rm CO})_2 ({\rm R}_2 {\rm PCH}_2)_3 {\rm CCH}_3][\mathop {{\rm Co}}\limits^{ - {\rm I}} ({\rm Co})_4] $\end{document} (R = C6H5) 2 setzt sich mit Alkalimetallhalogeniden und pseudohalogeniden MX (M = Na, K; X = Cl, Br, J, NCO, N3)unter UV-Bestrahlung zu den monomeren, paramagnetischen (μeff ≍ 3 B.M.), tetraedrischen Kobalt(I)-Komplexen XCo(R2PCH2CCH3 3um. Mit Co bilden die Halogeno-kobalt(I)-Komplexe 3a-c die ionischen, diamagnetischen Dicarbonylverbindungen [Co(CO)2(R2PCH2)CCH3]X (X = Cl, Br, J) 5. Die pseudohalogeno-kobalt(I)-Komplexe 3d, e reagieren dagegen mit CO jeweils zu dem nicht ionischen CO(NCO)(CO)2(R2PCH2C(CH3)CH2PR2 6 Der potentiell dreizähnige Ligand CH3C(CH2PR2)3 wirkt dabei lediglich zweifachkoordinierend-monometallisch. Die halogeno und Pseudohalogeno-kobalt(I) Komplexe 3 sind sehr oxidationsempfindlich. Bei den pseudohalogeno-kobalt(I)Komplexen 3d-e gelang es, im Festzustand die Bildung von O2-Komplexen qualitativ IR-spektroskopisch nachzuweisen. In Lösung zerfallen diese O2-Komplexe zu phosphinoxidhaltigen Produkten. 9,10-Phenanthrenchinon wird oxidativ an Co(NCO)(R2PCH2)3CCH3(3d) addiert. Es entsteht das paramagnetische Co(NCO)(C14H8O2)(R2PCH2)2C(CH3)CH2PR2 8 mit einem mittleren Spin von 2.97B. M. Die Verbindungen wurden IR- unf FIR- spektroskopisch untersucht.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19761090331
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    Rotationsbarriere der geometrischen Isomerisierung von cis-und trans-1,4-Dimethylbutatrien (1976)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 1158-1162 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Rotational Barrier for the Geometrical Isomerization of cis-and trans-1,4-DimethylbutatrieneThe synthesis of cis(3a) and trans-1,4-dimethylbutatriene (3b) is described. The activation parameters for the mutual interconversion of the geometrical isomers have been determined: Ea = 31.8 ± 0.3 kcal/mol; A= 1.1 × 1013S-1 (ΔH125°C≠ = 31.0 kcal/mol; ΔH125°C≠ = -1.5 cal/grad × mol). The equilibrium constant was found to be K = 1 in the temperature range 100-150°C.
    Notes: Die Synthese von cis-(3a) und trans-1,4-Dimethylbutatrien (3b) wird beschrieben. Für die wechselseitige Umlagerung der geometrischen isomeren wurden Aktivierungsparameter von Ea = 31.8 ± 0.3 kcal/mol und A= 1.1 × 1013 S-1 (ΔH125°C≠ = 31.0 kcal/mol; ΔS125°C≠ = -1.5 cal/Grad × mol) bestimmt. Im bereich von 100-150°C ist die Gleichgewichtskonstante dieser Reaktion K=1.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19761090337
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  • 274
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    Anisotropieeffekte Konjugierter, cyclischer Systeme, I: NMR-Spektren mesityl- und (9-anthryl)-substituierter Aromaten (1976)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 1184-1194 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Anisotropy Effects of Conjugated Cyclic Systems, I: N.M.R. Spectra of Mesityl- and (9-Anthryl)-substituted Aromatic CompoundsThe chemical shift differences Δδ of the n. m. r. signals of o-and p-methyl-groups in mesityl-substituted ring system are a measure of the magnetic anisotropy of aromatic systems. The same applies to the Δδ of the 1-H and 4-H signals of (9-anthryl)-substituents, but to a greater extent. The Δδ values for benzene, mesitylene, and anthracene as well as for pyrimidine, pyrazole, and isoxazole are reported and discussed.
    Notes: Die Differenz der chemischen Verschiebung Δδ von o-und p-Methylgruppen-Signalen in den NMR-Spektren mesitylsubstituierter Ringsysteme ist ein brauchbares Maß für die magnetische Anisotropie aromatischer Verbindungen. Das gleiche gilt noch verstärkt für die 1-H- und 4-H-Signale eines (9-Anthryl)-Substituenten. Δδ-Werte für Benzol, Mesitylen und Anthracen sowie Pyrimidin, Pyrazol und isoxazol werden mitgeteilt und besprochen.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19761090341
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    Nuceophile Thioacylierung mit Thiocarbamoyllithium-Derivaten von sek. Aminen (1976)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 1309-1323 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Nucleophilic Thioacylation with Thiocarbamoyllithium Derivatives of sec. AminesThe possibilities of direct H/metal-exchange at formyl groups to give unmasked nucleophilic acylating reagents C are considered. In contrast to nitrosamines of sec. amines which show CH-acidity at the saturated carbon next to nitrogen, thioformamides 1 are smoothly metalated at the formyl carbon (lithium diisopropylamide, THF-solvent, -100°C). The title compounds 2 thus available react in good yields especially with carbonyl compounds to produce thioamides 3 and 4 of higher α-hydroxycarboxylic acids. We did not succeed in generating stable lithiocarbamoyls 2d and 2j derived from phenyl substituted thioformamides. As Shown in scheme 1, the diphenylthioformamide anion 2j could be trapped in situ, while it appears to dimerize to 9 in the absence of electrophiles. The isolated products 11-13 can be considered as derivatives of 9.
    Notes: Die Möglichkeiten des direkten H/Metall-Austauschs an Formylgruppen zu unmaskierten nucleophilen Acylierungsmitteln C werden erörtert. Im Gegensatz Nitrosaminen sekundärer Amine wie, F, die neben dem Stickstoff am gesättigten Kohlenstoff CH-acid sind, werden Thioformamide 1 bei Temperaturen um -100°C in Tetrahydrofuran von Lithiumdiisopropylamid glatt am Formyl-C-Atom metalliert. Die so zugänglichen Thiocarbamoyllithium-Verbindungen 2 setzen sich in guten Ausbeuten vor allem mit Carbonylverbindungen um. Bei phenylsubstituierten Thioformamiden gelingt es nicht, für kurze Zeit stabile Lithiumcarbamoyle wie 2d oder 2j zu erzeugen. Wie in Schema 1 gezeigt, kann man das Diphenylderivat 2j aber in situ abfangen; in Abwesenheit eines Elektrophils entsteht offensichtlich ein Dimeres 9. dessen Folgeprodukte 11-13 isoliert wurden.
    Additional Material: 3 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19761090412
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    Lichtinduzierte Reaktionen, XI: Photochemische Öffnung linear-konjugierter Cyclohexadienone zu den seco-isomeren Dienylketenen (1976)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 1332-1345 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Light-Induced Reactions, XI: Photochemical Cleavage of Linearly Conjugated Cyclohexadienones Affording seco-Isomeric Dienyl KetenesThe light-induced cyclo/seco-isomerization of linearly conjugated cyclohexadienones has been studied taking 6,6-dimethyl-2,4-cyclohexadienone (1) as an example. The dienyl ketene 4, kinetically unstable at room temperature, is produced in a spectroscopically simple reaction by u.v. irradiation of 1 in aprotic solvents and can be trapped at temperatures 〈 -60°C. The structure of the transient as well as the heat-induced seco/cyclo-isomerization reforming 1 is proved by means of i.r., n. m. r., and electronic absorption spectroscopy at 〈 -60°C. In addition to or instead of recyclizing 4 adds protic nucleophiles. When 1 is irradiated with u.v. light in the presence of water or cyclohexylamine, 2a or b is formed in a spectroscopically simple reaction in yields of 〉 95%. The constitution of 2a,b and the orientation of ligands at the doubly substituted double bond follow unambiguously from reaction products and spectroscopic data. Since 1* does not show any detectable emission other evidence has to be used to identify the photoreactive electronic isomer and the corresponding spin isomer. The quantum yield, which is independent of the wave length of the exciting light (313 nm: π*, π excitation; 365nm: π*,n excitation), is in accord with the formation of the energetically lower π*,n electronic isomer; the observation that the photoreaction is not quenched by piperylene indicates the occurrence of the singlet spin isomer, although an extremly short-lived triplet spin isomer cannot be rigorously excluded.  -  The equipment for the determination of quantum yields and the i.r. cell for use at variable temperatures are presented in detail.
    Notes: Am Beispiel von 6,6-Dimethyl-2,4-cyclohexadienon (1) wurde die lichtinduzierte Cyclo/seco-Isomerisierung linear-konjugierter Cyclohexadienone studiert. Durch UV-Bestrahlung von 1 in aprotischen Lösungsmitteln bei Temperaturen 〈-60°C läßt sich das in einer spektroskopisch einheitlichen Reaktion entstehende, bei Raumtemperatur kinetisch instabile Dienylketen 4 „einfrieren“. Ir-, NMR- und Elektronenabsorptions-Spektroskopie bei 〈-60°C belegen die Struktur des Transienten sowie die praktisch vollständig verlaufende, wärmeinduzierte seco/cyclo-Isomerisierung zu 1. Zusätzlich zu oder statt der Fähigkeit zu recyclisieren lagert 4 protische Nucleophile an. Wird 1 in Gegenwart von Wasser oder Cyclohexylamin mit UV-Licht bestrahlt, so erhält man in einer spektroskopisch einheitlichen Reaktion 2a oder b mit Ausbeuten von 〉 95%. Ihre Konstitution und Ligandenorientierung an der zweifach substituierten Doppelbindung wurden durch Folgeprodukte und Spektren sichergestellt. Da 1* keine nachweisbare Emission erkennen läßt, müssen für die Identifizierung des photoreaktiven Elektronenisomeren sowie des zugehörigen Spinisomeren andere Indizien herangezogen werden. die von der Wellenlänge des eingestrahlten Lichts (313 nm: π*, π-Anregung; 365 nm: π*, n-Anregung) unabhängige Quantenausbeute spricht für das Energetisch tiefer liegende π*, n-Elektronenisomere, die nicht stattfindende Reaktionslöschung durch Piperylen für das Auftreten des Singulett-Spinisomeren, Ohne daß ein extrem kurzlebiges Triplett-Spinisomeres ausgeschlossen werden kann. Die Apparatur zur Bestimmung der Quantenausbeute sowie die Küvette zur spektroskopischen Messung im IR-Bereich bei variabler Temperatur werden in einzelnen beschrieben.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19761090414
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    Nucleosidtransformationen, 2: Selektive Oxiranringöffnung von 9-(2,3-Anhydro-β-D-ribofuranosyl)- und 9-(2,3-Anhydro-β-D-lyxofuranosyl)adenin (1976)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 1395-1406 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Nucleoside Transformations, 2: Selective Oxirane Ring Opening of 9-(2,3-Anhydro-β-D-ribofuranosyl)-and 9-(2,3-Anhydro-β-D-lyxofuranosyl)adenineOxirane ring opening of 9-(2,3-anhydro-β-D-ribofuranosyl)adenine (1) with hydrogen chloride or hydrogen bromide yields 3′-chloro-or 3′-bromo-3′-deoxy-xylo-adenosine (2 or 4). The corresponding 3′-iodo compound 6 was obtained by treating 1 with sodium iodide in the presence of boron trifluoride etherate. Treatment of 9-(2,3-anhydro-β-D-lyxofuranosyl)adenine (8) with boron trifluoride etherate/alkali metal halides gives mixtures of the 3′- and 2′-halogenonucleosides: lithium chloride yields 9 and 10, lithium bromide 11 and 12, sodium iodide 13 and 14. In the mixtures the 3′-halogeno isomers 9, 11 and 13 predominate. The best yield (18%)of a 2′-halogenonucleoside (12) was obtained using lithium bromide. The bromohydrines 11 and 12 can be converted into the epimers of 3′-deoxy- and 2′-deoxyadenosine 15, 16 by treatment with tributyl tin hydride.
    Notes: Oxiranringöffnung von 9-(2,3-Anhydro-β-D-ribofuranosyl)adenin (1) mit Chlor- bzw. Bromwasserstoff gibt 3′-Chlor- bzw. 3′-Brom-3′-desoxy-xylo-adenosin (2 bzw. 4) Die entsprechende 3′-Jodverbindung 6 wird aus 1 durch Einwirkung von Natriumjodid in Gegenwart von Bortrifluorid ätherat erhalten. Die Bortrifluorid-ätherat/Alkalihalogenid-Mischung, auf 9-(2,3-Anhydro-β-D-lyxofuranosyl)adenin (8) angewandt, führt zu einem Gemisch an 3′- und 2′-Halogennnucleosiden: Lithiumchlorid ergibt 9 und 10, Lithiumbromid 11 und 12 Natriumjodid 13 und 14. In den Gemischen überwiegen die 3′-Halogenisomeren 9, 11 bzw. 13 und der größte Prozentsatz (18%) an 2′-Halogennucleosid (12) entsteht mit Lithiumbromid. Die beiden Bromhydrine 11 und 12 lassen sich mit Tributylzinnhydrid in die Epimeren von 3′-Desoxy-und 2′-Desoxyadenosin 15, 16 überführen.
    Additional Material: 3 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19761090422
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    Natürlich vorkommende Terpen-Derivate, 58: Über Inhaltsstoffe der Gattung Brickellia (1976)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 1436-1445 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Naturally Occurring Terpene Derivatives, 58: Constituents of the Genus BrickelliaBesides a dehydronerolidol derivative (2) and a benzofuran derivative (14) several new diterpenes (3, 9, 17, 18, 27, and 28) have been isolated. Their structures are elucidated by spectroscopic methods and some chemical reactions. 9 is an new type of degraded diterpene which, however, is closely related to 3.
    Notes: Neben einem Dehydronerolidol-Derivat (2) und eine, Benzofuran-Derivat (14) werden mehrere neue Diterpene (3, 9, 17, 18, 27 und 28) isoliert. Ihre Strukturen werden durch spektroskopische Methoden und einige chemische Reaktionen geklärt. 9 ist ein neuer Typ eines abgebauten Diterpens, der jedoch in enger Beziehung zu 3 steht.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19761090428
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    Methylkobaltverbindungen mit nicht chelatisierenden Liganden, III: Dimethyltris (trimethylphosphin)kobalt(II) und seine Derivate (1976)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 1453-1464 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Methylcobalt Compounds with NOn-Chelating Ligands, III: Dimethyltris(trimethylphosphine)cobalt(II)and its DerivativesSyntheses and properties of the pentacoordinated d7 -complexes CoX2L3 (L = (CH3)3 P; X = Cl, Br, I, CH3) are reported. Pentacoordination is also attributed to a hydride CoHL4⊕ Cl⊖. The title compound is oxidized by bromine or iodine to give methylcobalt(III) complexes. Weak acids HX cleave both Co-C bonds to form coordination polymers of the composition CoX2 (X = OCH3, OC6H5, acac). As Intermediates the methylcobalt (II) complexes [CoCH3(OCH3)L2]2 and CoCH3(acac)L2 (L = (CH3)3P) are isolated. From the reaction of the title compound with NO diamagnetic methylcobalt complexes are obtained. Primarily formed Co(CH3)2(NO)L2 rearranges via NO insertion into a Co—C bond to give [CoCH3(CH3NO)L2]2 (L = (CH3)3P), a dinuclear complex containing nitrosomethane bridge. The carbonylation reaction yields diamagnetic compounds Co(COCH3)(CO)2L2 and [Co(CO)2L2]2 (L = (CH3)3P) besides acetone.
    Notes: Es wird über Darstellung und Eigenschaften der pentakoordinierten d7-Komplexe CoX2L3 (L = (CH3)3P X = Cl, Br, J, CH3 berichtet. Pentakoordination wird auch einem Hydridkomplex CoHL4⊕Cl⊖ zugeschrieben. Die Oxidation der Titelverbindung mit Brom oder Jod führt zu Methylkobalt(III)-Komplexen. Schwache Säuren HX spalten beide Co—C-Bindungen und bilden Koordinationspolymere der Zusammensetzung CoX2 (X = OCH3, OC6H5, acac). Als Zwischen-stufen werden die Methylkobalt(II)-Komplexe [CoCH3(OCH3)L2]2 und CoCH3(acac)L2 (L = (CH3)3P) isoliert. Aus der Reaktion dr Titelverbindung mit NO erhält man diamagnetische Methylkobaltkomplexe. Primär gebildetes Co(CH3)2(NO)L2 lagert sich unter NO_Einschiebung in eine Co-C-Bindung zu [CoCH3(CH3NO)L2] (L = (CH3)3P) um, einem Zweikernkomplex mit brückenbildenden Nitrosomethan-Liganden. Die Carbonylierung ergibt die diamagnetischen Verbindungen Co(COCH3)(CO)2L2 und [Co(CO)2L2]2 neben Aceton.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19761090431
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    Metallkomplexe mit Tetrapyrrol- Liganden, XVII: Achtfach koordinierte Zirkonium (IV)- und Hafnium (IV)- Porphine mit axialen 1,3-Diketonat-Liganden (1976)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 1477-1485 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Metal Complexes of Tetrapyrrole Ligands, XVII: Octacoordinate Zirconium and Hafnium Porphines Containing Axial 1,3-Diketonate LigandsNew (1,3-diketonato)Metalloporphyrins Zr(OÄP)(acac)2 (3a), Hf(OÄP)-(dbm)2 3c, Hf(OÄP)(dbm)2 (3d), and Zr(OÄP)(acac)OPh (5)2 are prepared and characterized spectroscopically. By analogy to the structurally secured acetato complexes, e. g. Zr(OÄP)(OAc)2 (2a), the central metal ions in 3a-d are regarded as octacoordinate with bidentate axial ligands. This follows from the i.r. and 1H n.m.r. spectra. The cis-configurations 3A of 3a-d and 5A are compared with the configuration 1A, 2A, and 4A of related species.
    Notes: Neue (1,3-Diketonato)metallporphyrine Zr(OÄP)(acac)2 (3a), Hf(OÄP)(acac)2 (3b), Zr(OÄP)-(dbm)2 (3c), Hf(OÄP)(dbm)2 (3d) und Zr(OÄP)(acac)OPh (5) 2 werden dargestellt und spektroskopisch charakterisiert. In Analogie zu den strukturell gesicherten Acetatkomplexen, z. B. Zr(OÄP)(OAc)2 (2a), wird den Zentralmetall-lonen in 3a-d die Koordinationszahl 8 mit zweizähnig gebundenen Axial-Liganden zugeschrieben. Dies ergibt sich aus den IR- und 1H-NMR-Spektren. Die cis-Konfigurationen 3A von 3a-d und 5A werden mit den Konfigurationen 1A 2A und 4A einiger verwandter Spezies verglichen.
    Additional Material: 3 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19761090433
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    Die Phosphoran-Phosphin-Umlagerung; Mechanismus und Stereochemie (1976)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 1497-1505 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The Phosphorane-Phosphine-Rearrangement; Mechanism and StereochemistryOrganylbis(4,4′-dimethyl-2,2′-biphenylylene)phosphoranes 6 rearrange Thermally to two types of phosphines 7 and 13. Stereochemically these can be treated as bridged biphenyl system or tetrabenzophosphonine systems on the one hand and as biphenyl systems which are substituted in their 2,2′-position by large groupe on the other hand.
    Notes: Organylbis(4,4′-dimethyl-2,2′-biphenylylen)phosphorane 6 lagern thermisch zu zwei Phosphin Typen 7 und 13 um, die stereochemisch als verbrückte Biphenyl-Derivate oder Tetrabenzophosphonin-System einerseits und als mit großen Gruppen 2,2′-disubstituierte Biphenyl-Derivate andererseits behandelt werden können.
    Additional Material: 2 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19761090436
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    Natürlich vorkommende Terpen-Derivate, 59: Über neue Diterpene aus Dimorphotheca pluvialis Moench (1976)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 1446-1449 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Naturally Occurring Terpene Derivatives, 59: On New Diterpenes from Dimorphotheca pluvialis Moench.Besides small amounts of known acetylenes the investigated plant contains five new diterpenic acids (5, 7, 9, 11 and 12), their structures being elucidated by spectroscopic methods. The relationship to these compounds to the diterpenes in other genera of the same tribe are discussed.
    Notes: Neben kleinen Mengen bekannter Acetylene enthält die untersuchte Pflanze fünf neue Diterpen-säuren (5, 7, 9, 11 und 12 deren Strukturen durch spektroskopische Methoden geklärt werden. Die Beziehungen dieser Verbindungen zu den Diterpenen in anderen Gattungen der gleichen Tribus werden diskutiert.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19761090429
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    Metall-Komplexe mit Tetrapyrrol-Liganden, XVI: Methoxonitrosyl(octaäthylporphinato)osmium (II) und verwandte Osmiumkomplexe des Octaäthylporphins (1976)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 1465-1476 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Metal Complexes of Tetrapyrrole Ligands, XVI: Methoxonitrosyl(octaethylporphinato)osmium(II)and related Osmium Complexes of OctaethylporphineThe new diamagnetic nitrosyl(octaethylporphinato)osmium (II) derivatives Os(OÄP)NO· L′(2c-e; L′ = NO, OMe, or F)2 are prepared and characterized spectroscopically. According to the electronic absorption, i.r., and 1H n.m.r. spectra fo the bis(methoxo)osmium(IV) derivative Os(OÄP)(OMe)2 (2f) and of the nitrosyls 2d, e, the latter contain OsII with an linear N≡O⊕ group and an anion OMe⊖ or F⊖ in the trans position. The strong π-acceptor NO⊕ and the strong π-donator OMe⊖ (or F⊖) effect a push-pull stabilization of the system. The dinitrosyl 2c probably shows the rare trans-array of linear M — N ≡ O⊕ and an bent M — N = O⊖ unit. The porphine ligand acts as a probe of the π-acceptor capacity of the axial ligands; in the series Py 〈 N2 〈 CO 〈 NO⊕ an increasing bathochromic shift of the α-band in the spectral region from 510 to 580 nm obtains.
    Notes: Neue, diamagnetische Nitrosyl(octaäthylporphinato)osmium(II)-Derivate OS(OÄP)NO· L′(2c bis e; L′ = NO, OMe oder F)2 werden dargestellt und spektroskopisch charakterisiert. Nach einem Vergleich der Elektronenanregungs-, IR- und 1H-NMR-Spektren des Bis(methoxo)osmium(IV) Derivats Os(OÄP)(OMe)2 (2f) und der Nitrosyl 2d, e liegt in der letzteren Os11 mit linearer N ≡ O⊕-Gruppierung und trans-ständigem Anion OMe⊖ oder F⊖ vor. Der starke π-Acceptor NO⊕ und der starke π-Donator OMe⊖ (oder F⊖) bewirken eine „push-pull“ -Stabilisierung des Systems. Im Dinitrosyl 2c light wahrscheinlich die seltene trans-Anordnung einer Linearen M—N≡O⊕- und einer gewinkelten M—N=O⊖-Einheit vor. Der Porphin-Ligand wirkt als Sonde für die π-Acceptorstärke der axialen Liganden; in der Reihe Py 〈 N2 〈 CO 〈 NO⊕ erfolgt eine zunehmend bathochrome Verschiebung der α-Bande im Spektralbereich von 510 bis 580 nm.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19761090432
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    Reaktionen mit Cyclobutendionen, XLII: Umsetzung des Diphenylcyclobutendions mit Methylenphosphoranen (1976)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 1506-1515 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reactions of Cyclobutenediones, XLII: Reactions of Diphenylcyclobutenedione with MethylenephosphoranesDiphenylcylobutenedione (1a) reacts with the methylenephosphoranes 4a-z to give the substituted 4-methylene-2,3-diphenyl-2-cyclobuten-1-ones 5a-p, t-z and 5u′-z. Structural proof of the products is given by spectroscopic methods. The unsubstituted compound 5r is not obtained. Wittig reaction of (2,5-dimethoxyphenyl)phenylcyclobutenedione (1d) with 4u proceeds nearly stereoselectively to give 9D.
    Notes: Diphenylcyclobutendion (1a) reagiert mit den Methylenphosphoranen 4a-z zu substituierten 4-Methylen-2,3-diphenyl-2-cyclobuten-1onen 5a-p, t-z bzw. 5u′-z, deren Struktur spektroskopisch gesichert wird. Die Synthese des Grundkörpers 5r gelingt nicht. Die Wittig-Reaktion am (2,5-Dimethoxyphenyl) phenylcyclobutendion (1d) mit 4u verläuft annähernd stereoselektiv zu 9D.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19761090437
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    Notiz zur Umwandlung schwefelverbrückter Carbonylkomplexe des Mangans und Rheniums mit CO unter Druck (1976)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 1569-1571 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19761090442
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    Notiz über zwei neue Cumarin-Derivate aus Machaeranthera scabrella (Greene) Shinners (1976)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 1584-1585 
    Details
    ISSN: 0009-2940
    Keywords: 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.19761090447
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  • 287
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    Stereospezifische Br/O Ac-Substitution an syn- und anti- 11- Brom-2,3-benzotricyclo[4.4.1.0]undecen-4-onen. Die Retentive Substitution am Dreiring (1976)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 1589-1600 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Stereospecific Br/O Ac-Substitution at syn- and anti-11-Bromo-2.3-benzotricyclo[4.4.1.0] undecen-4-one. The Retentive Substitution at CyclopropanePossible mechanisms A - G of the nucleophilic substitution at cyclopropane carbons are discussed. Special attention is given to the retentive replacements D and E which hitherto have not been observed. A smooth, stereospecific Br/OAc-substitution under typical SN2-type conditions is described for the syn/anti-isomers 6a and 7a. From the n.m.r. spectra of the four compounds 6a, b and 7a, b it is concluded that these substitutions occur under retention of configuration which is confirmed by X-ray analysis of the crystalline pair 7a, b.
    Notes: Mögliche mechanismen A - G der nucleophilen Substitution an Cyclopropanen werden unter besonderer Berücksichtigung der bisher nicht beobachteten Retention nach D oder E diskutiert. Am Beispiel der syn/anti-Isomeren 6a und 7a wird eine Br/OAc-Substitution beschrieben, die stereospezifisch unter typischen SN2-Bedingungen erfolgt. Aus den NMR-Spektren der vier Verbindungen 6a, b und 7a, b kann man schließen diese Substitutionen unter Retention der Konfiguration ablaufen. Die Röntgenstrukturanalyse des kristallinen Paares 7a, b bestätigt dies.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19761090501
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    Notiz über lie Darstellung von Carbenanalogen Germylenen mit Arylthio- und Alkylthioliganden (1976)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 1575-1576 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19761090444
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  • 289
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    Untersuchungen über Verbindungen mit Berban-Gerüst, III. Regiospezifische Synthese der Despyrroloyohimbinone durch Dieckmann-Kondensationen von ungesättigten Estern (1976)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 1724-1736 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Investigation on the Chemistry of Berbans, III. Regiospecific Synthesis of Depyrroloyohimbinone by Dieckmann Condensation of unsaturated EstersDieckmann-ring closure of unsaturated-saturated esters (1-4) leads to products (6-10) whose stereochemistry is predominantly controlled by the configuration of the starting material. The reaction is useful for the regio-and stereoselective construction of berban derivatives.
    Notes: Untersuchungen des Dieckmann-Ringschlusses von gesättigt-ungesättigten Dicarbonsäureestern (1-4) zeigen, daß die Produkte (6-10) vor allem von der Konfiguration des Ausgangsmaterials abhängen. Die Reaktion ist zum regioselektiven und stereoselektiven Aufbau von Berban-Derivaten sehr nützlich.
    Additional Material: 1 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19761090516
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  • 290
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    Carben-Reaktionen, VI. Addition von Dimethoxycarben an Heterodiene (1976)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 1759-1768 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Carbene Reactions, VI. Addition of Dimethoxycarbene to HeterodienesDimethoxycarbene (2) has been added to N-acylimines of hexafluoroacetone (6) forming oxazolines 7. It has been shown by competition experiments, that free dimethoxycarbene is generated in the reactions of 6 with trimethyl orthoformate (3).
    Notes: Dimethoxycarben (2) addiert sich an eine Reihe von N-Acyliminen des Hexafluoracetons (6) zu den Oxazolinen 7. Durch Konkurrenzversuche konnte gezeigt werden, daß bei der Einwirkung von 6 auf Orthoameisensäureester (3) freies Dimethoxycarben (2) auftritt.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19761090519
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  • 291
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    Umlagerung von bicyclo[5.1.0]octa-2,4-dien-Derivaten durch Säuren (1976)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 1856-1867 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Rearrangement of Bicyclo[5.1.0]octa-2,4-diene Derivatives by AcidsThe addition of acids to bicyclo [5.1.0] octa-2,4-dienes mat proceed with rearrangement to bicyclo-[3.2.1] oct-2-enes. A donor substituent at C-8 is essential for this transformation, as shown by the decreasing tendency of 1 (NHCOCH3), 19 (OCH3), and (33) H) to form bicyclo [3.2.1] octenes. Cycloheptadienylmethyl derivatives are formed in a competing reaction. Regardless of the configuration of the starting material (19a, b), 4-exo-8-anti-substituted bicyclo [3.2.1] oct-2-enes are obtained. Configurations were established by n. m. r. and by unequivocal synthesis of 25. The reaction is thought to involve protolysis of the cyclopropane ring to a homoallyl cation 36 which undergoes cyclization to 38 (formally a 1,4 shift).
    Notes: Die Addition von Säuren an Bicyclo[5.1.0] octa-2,4-diene kann unter Umlagerung zu Bicyclo [3.2.1] oct-2-enen verlaufen. Ein Donor-Substituent an C-8 ist Voraussetzung für diese Umwandlung, wie aus der abnehmenden Tendenz von 1 (NHCOCH3), 19 (OCH3) und 33 (H) zur Bildung von Bicylo [3.2.1] octenen hervorgeht. In einer konkurrierenden Reaktion entstehen Cycloheptadienylmethyl-Derivate. Unabhängig von der Konfiguration des Ausgangsmaterials (19a, b) werden 4-exo-8-anti -substituierte Bicyclo [3.2.1.] oct-2-ene erhalten. Die Konfigurationen wurden durch NMR und eindeutige Synthese von 25 festgelegt. Die Reaktion beginnt wahrscheinlich mit der Protolyse des Cyclopropanrings zum Homoallylkation 36, das zu 38 cyclisiert (formal eine 1,4-Verschiebung).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19761090528
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    [1,5]-Sigmatrope Esterverschiebung am Pentakis (methoxycarbonyl)cyclopentadien-System (1976)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 1918-1927 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: [1,5]-Sigmatropic Ester Shift in the Pentakis(methoxycarbonyl)cyclopentadiene System5-Alkyl-pentakis(methoxycarbonyl)cyclopentadienes (1) equilibrate at 100°C with 1-alkyl-pentakis(methoxycarbonyl)cyclopentadienes (2) via 1,5-sigmatropic ester shifts. At higher temperatures a further ester shift generates the 2-alkyl-pentakis(methoxycarbonyl)cyclopentadienes (3). The intramolecular character of the rearrangement is demonstrated by crossover experiments.
    Notes: 5-Alkyl-pentakis(methoxycarbonyl)cyclopentadiene (1) äquilibrieren bei 100°C durch [1,5]-sigmatrope Esterverschiebung mit 1-Alkyl-pentakis(methoxycarbonyl)cyclopentadienen (2). Bei höheren Temperaturen führt eine weitere Esterverschiebung zu 2-Alkyl-pentakis(methoxycarbonyl)cyclopentadienen (3). Der intramolekular Verlauf der Umlagerung wurde durch Kreuzungsversuche gesichert.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19761090533
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    Über Phosphazene, LIV. Synthese und Struktur von 2,2′-Dimethyl-octaphenyl-2,2′-bi[cyclotri(phosphazen)yl] (1976)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 1911-1917 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Phosphazenes, LIV. Synthesis and Structure of 2,2′-Dimethyl-octaphenyl-2,2′-bi[cyclotri(phosphazen)yl]Metallation fo the hydrido-cyclophosphazene 1 and subsequent reaction with the chloro-cyclo-phosphazene 4 yields the title compounds 6. This is also obtained by reduction of 4 and from the disproportionation of the phosphino-cyclophosphazen 5. 6 has a centrosymmetric structure (determined by X-ray analysis), which may be compared to that of N3P3(C6H5)6 in respect to the phosphazene rings and to (CH3)4P2S4 as far as the central diphosphane part is concerned. I. r., 31 P, and 1 H n. m. r. spectra are discussed.
    Notes: Die Titelverbindung 6 wird aus dem Hydrido-cyclophosphazen 1 durch Metallieren und Umsetzen mit dem Chlor-cyclophosphazen 4 dargestellt. Sie bildet sich auch durch Reduktion von 4 und Disproportionieren des Phosphino-cyclophosphazens 5. 6 besitzt zentrosymmetrische Struktur (durch Röntgenstrukturanalyse bestimmt), die sich bezüglich des Ringgerüsts mit N3P3(C6H5)6 und bezüglich der zentralen Diphosphan-Gruppierung mit (CH3)4P2S2 vergleichen läßt. IR-, 31P- und 1H-NMR-Spektren werden diskutiert.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19761090532
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  • 294
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    Zur Synthese thioanaloger Cannabis-Derivate (1976)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 2164-2174 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis of Thio-CannabinoidsThe base-catalyzed reaction of pulegone (3) with the thiophenols 4a-d yields the γ-ketothioethers 5a-d, the cyclization of which produces the dibenzo[b,d]thiopyrans 6a-c. The cyclization of 5a and b also produces the thioxanthenes 7a, b as by-products. The thiopyrans 6a-c as well as 6a-c can be oxidized to the sulfones 10a-c with m-chloroperbenzoic acid. 6a-c can be demethylated to the free thio-analogous Δ6a(10a)-cannabinoid derivatives 11a-f by sodium ethanethiolate. Dehydrogenation of 11a-c by sulfur yields the analogous cannabinoids 15a-c. The structures of the compounds obtained are characterized by n. m. r., i. r., and mass spectra.
    Notes: Pulegon (3) wird basenkatalysiert an die Thiophenole 4a-d zu γ-Ketothioäthern 5a-d addiert, deren Cyclisierung Dibenzo[b,d]thiopyrane 6a-c liefert. Als Nebenprodukte entstehen bei der Cyclisierung von 5a und b auch die Thioxanthene 7a, b. Die Thiopyrane 6a-c lassen sich mit m-Chlorperbenzoesäure zu den Sulfonen 10a-c oxidieren. Sowohl 6a-c als auch 10a-c Können mit Natrium-äthanthiolat zu den freien thioanalogen Δ6a(10a)-Cannabis-Derivaten 11a-f demethyliert werden. Mit der Dehydrierung von 11a-c durch Schwefel erhält man die analogen Cannabinole 15a-c. Die Strukturen der erhaltenen Verbindungen werden durch NMR-, IR- und MS-Spektren Charakterisiert.
    Additional Material: 6 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19761090623
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    Polycarbonylverbindungen, XVI. Darstellung und Struktur des Schwefelanalogons des Quadratsäure-Dianions K2[C4S4]·H2O (1976)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 2208-2215 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Polycarbonyls, XVI. Synthesis and Structure of the Sulfur Analogue of Squaric Acid Dianion K2[C4S4·H2O]Sulfhydrolysis of 1,2- or 1,3-dithiosquaric acid diamides yields the sulfur analogue 4 of squaric acid dianion, the first member of the „thioxocarbons“. Spectroscopic data and intramolecular distances determined by X-ray diffraction indicate a symmetrical, delocalised electron system with C—C- and C—S-bond orders of n - 1.25 and 1.5, resp.
    Notes: Durch Sulfhydrolyse von 1,2- bzw. 1,3-Dithioquadratsäure-bisamiden entsteht das Schwefelanalogon 4 des Quadratsäure-Dianions, der erste Vertreter der „Thioxokohlenstoffe“. Spektroskopische Daten und die aus einer röntgenographischen Strukturbestimmung erhaltenen innermolekularen Bindungslängen weisen auf ein symmetrisches, delokalisiertes Elektronensystem mit C — C- bzw. C — S-Bindungsordnungen von n = 1.25 bzw. 1.5 him.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19761090627
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  • 296
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    Derivate des Borabenzols, VIII: Ein neuer Weg zu Alkalimetallborinaten. Synthesen von Ruthenium-, Osmium-, Rhodium- und Platin-Verbindungen mit Borinat-Liganden (1976)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 2382-2388 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Borabenzene Derivatives, VIII: A New Route to Alkalimetal Borinates. Syntheses of Ruthenium, Osmium, Rhodium, and Platinum Compounds with Borinate LigandsDegradation of bis(borinato)cobalt complexes Co(C5H5B — R)2(R = C6H5, CH3) with alkalimetal cyanides MCN (M = Na, K) yields alkalimetal borinates M[C5H5B — R]. These are versatile synthetic intermediates as demonstrated by the syntheses of Ru(C5H5B — R)2 (R = C6H5, CH3), Os(C5H5B — C6H5)2, Rh(1,5-C8H12)(C5H5B — R), and Pt(CH3)3(C5H5B — C6H5).
    Notes: Der Abbau von Bis(borinato)kobalt-Komplexen Co(C5H5B — R)2 (R = C6H5, CH3) mit Alkalimetallcyaniden MCN (M = Na, K) liefert Alkalimetallborinate M[C5H5B — R]. Diese sind vielseitige Synthesezwischenprodukte, wie mit der Darstellung von Ru (C5H5B — R)2 (R = C6H5,CH3), Os(C5H5B — C6H5)2, Rh(1,5-C8H12)(C5H5B — R) und Pt(CH3)3((C5H5B — C6H5) gezeigt wird.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19761090704
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    Kondensationsreaktionen von Schwefeltetrafluorid mit Iminophosphoranen (1976)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 2442-2455 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Condensation Reactions of Sulfur Tetrafluoride with IminophosphoranesThe reaction of iminophosphoranes with SF4 is qualified for the syntheis of symmetric and unsymmetric substituted sulfur diimides 1a, b and bis(sulfur diimides) 4a - d, bis(iminosulfurdifluorids) 3a - e, cyclic sulfur diimides 6a - d, f, and 1,2,5-thiadiazoles 10a - e. Some reactions of the new substances are described.
    Notes: Die Umsetzung von Iminophosphoranen mit SF4 eignet sich zur Darstellung von symmetrisch und unsymmetrisch substituierten Schwefeldiimiden 1a, b und Bis(schwefeldiimiden) 4a - d, Bis(iminoschwefeldifluoriden)3a-e, cyclischen Schwefeldiimiden 6a -d, f und 1,2,5-Thiadiazolen 10a - e. Einige Reaktionen der neuen Substanzklassen werden hier beschrieben.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19761090711
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    Basisches Verhalten von Epoxiden in Gegenwart von Halogenid-Ionen, IV: gem-Difluorcyclopropane aus Chlordifluormethan und Alkanolat-Ionen in geringer Konzentration (1976)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 2351-2369 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Basic Behavior of Epoxides in the Presence of Halide Ions, IV. gem-Difluorocyclopropanes from Difluorocarbene, Generated from Chlorodifluoromethane and Alkoxide Ions in Small Concentrationgem-Difuorocyclopropanes are formed in high yields from chlorodifluoromethane, alkanolate ions, and reactive alkenes (table 1), provided that the concentration of alkanolate is small. Alkanolates of the necessary small concentration are found in a solution of halide ions in epoxides(eq. (3)). Suitable epoxides are (chloromethyl)oxirane and oxirane (ethylene oxide). The conversion is increased by increasing concentration of chloride ions (fig. 1, curve A) and decreased by increasing concentration of alcohol (tab. 4). With less reactive olefines are formed not only the desired gem-difluorocyclopropanes but also the products of reaction between difluorocarbene and alcohols (compounds 9, 11, 12). The structures both of the gem-difluorocyclopropanes and of the by-products are determined mainly by n.m.r. (1H, 13C, 19F).
    Notes: gem-Difluorcyclopropane entstehen in hohen Ausbeuten aus Chlordifluormethan, Alkanolat und reaktiven Alkenen (Tab. 1), sofern die Konzentration an Alkanolat sehr klein ist. Die Alkanolat-lonen in der erforderlichen geringen Konzentration enthält eine Lösung von Halogenid-Ionen in Epoxiden (Gi. (3)). Gebräuchliche Epoxide sind (Chlormethyl)oxiran und Oxiran (Äthylenoxid). Der Umsatz wird durch zunehmende Chlorid-Ionen-Konzentration erhöht (Abb. 1, Kurve A)und durch Zunehmende Alkohol-Konzentration Herabgesetzt (Tab. 4). Mit weniger reaktiven Alkenen erhält man nicht nur die gewünschten gem-Difluorcyclopropane, sondern auch Produkte der Umsetzung zwischen Difluorcarben und Alkoholen, wobei die Verbindungen 9, 11 und 12 entstehen. Die Strukturen der gem-Difluorcyclopropane und der Nebenprodukte werden hauptsächlich durch die NMR-Spektren (1H, 13C, 19F) belegt.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19761090702
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    Darstellung und Stereochemie von 1,2,3,4,9-Pentaphenyl-9H-tribenzo[b,d,f]phosphepin (1976)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 2405-2419 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis and Stereochemistry of 1,2,3,4,9-Pentaphenyl-9H-tribenzo[b,d,f]phosphepinThe synthesis of conformational isomeric tribenzo[b,d,f]phosphepin oxides (7A, B) has been achieved by transition metal-catalysed trimerisation of the triarylphosphinoxide bisacetylene 4. The use of dichlorobis(benzonitrile)palladium affords the novel palladium phosphinoxide complex 8. The free enthalpie of activation for the conformational change is determined in the case of the tribenzo[b,d,f]phosphepin oxides. Reduction with trichlorosilane affords the conformationally isomeric tribenzo[b,d,f]phosphepins 11A,B. The steric course of this reduction is discussed in detail. The kinetic data of the ringinversion are determined by the use of 31 P n.m.r. spectroscopy. With methyl iodide, the phosphonium salts 12A, B are formed from the tribenzo[b,d,f]phosphepins, which correspond formally to the tribenzotropylium cation. The lowered free enthalpie of activation of the ring inversion is interpretable by a cyclic conjugation in the transition state.
    Notes: Durch übergangssmetallkatalysierte Acetylen-Trimerisierung des Triarylphosphinoxid-Bisacetylens 4 mit Tolan gelingt die Darstellung konformationsisomerer Tribenzo[b,d,f]phosphepinoxide (7A,B). Die Verwendung von Bis(benzonitril)palladiumdichlorid führt zu dem bisher unbekannten Phosphinoxid-Palladium-Komplex 8. Die Freie Aktivierungsenthalpie für die Konformations-änderung der Tribenzo[b,df]phosphepinoxide wird bestimmt. Mit Trichlorsilan erhält man die konformationsisomeren Tribenzo[b,df,]phosphepine 11A, B wobei der sterische Reduktionsverlauf näher diskutiert wird. Die kinetischen Daten der Ringinversion werden mit Hilfe der 31P-NMR-Spektroskopie ermittelt. Die Tribenzo[b,d,f]phosphepine liefern mit Methyljodid Phosphoniumsalze (12A, B), die formal dem Tribenzotropylium-Kation entsprechen. Eine Erniedrigung der Freien Aktivierungsenthalpie bei der Ringinversion deutet auf eine cyclische Konjugation im Übergangszustand.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19761090707
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    Polycyanbenzole V: Ein einfacher Zugang zum Tetracyanhydrochinon. Darstellung der 1,4-Dihalogen-tetracyanbenzole (1976)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 2462-2468 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Polycyanobenzenes, V: An Easy Access to Tetracyanohydroquinone. Preparation of the 1,4-Dihalogeno-tetracyanobenzenesChloranil (6), bromanil (1), 2,5-dibromo-3,6-dimethoxy-p-benzoquinone (4), and 2,3-dichloro-5,6-dicyano-p-benzoquinone (8) react with cyanide ions to give the corresponding ortho-dicyanosubstituted hydroquinones 2,5, and 7 as well as tetracyanohydroquinone (3). With phosphoryl halides/pyridine, 3, its dimethyl ether 3a, and its diacetate 3b yield 1,4-dichloro- (15) and 1,4-dibromo-2,3,5,6-tetracyanobenzene (16). Similarly 1,3,5-tricyano-2,4,6-trimethoxybenzene (17) is converted into 1,3,5-tribromo-24,6-tricyanobenzene (18). Reaction of 15 with potassium fluoride or potassium iodide yields 1,2,4,5-tetracyano-3,6-difluorobenzene (19) and 1,2,4,5-tetracyano-3,6-diiodobenzene (20), resp.
    Notes: Chloranil (6), Bromanil (1), 2,5-Dibrom-3,6-dimethoxy-p-benzochinon (4) und 2,3-Dichlor-5,6-dicyan-p-benzochinon (8) reagieren mit Cyanid-Ionen zu den entsprechenden ortho-dicyan-substituierten Hydrochinonen2,5 und 7 sowie zum Tetracyanhydrochinon (3). Durch Einwirkung von Phosphorylhalogenid/Pyridin auf 3, dessen Dimethyläther 3a oder das Diacetat 3b entsteht 1,4-Dichlor-(15) bzw. 1,4-Dibrom-2,3,5,6-tetracyanbenzol (16). Nach der gleichen Methode wird aus 1,3,5-Tricyan-2,4,6-trimethoxybenzol (17) das 1,3,5-Tribrom-2,4,6-tricyanbenzol (18) erhalten. Die Umsetzung von 15 mit Kaliumfluorid bzw. Kaliumjodid ergibt 1,2,4,5-Tetracyan-3,6-difluorbenzol (19) bzw. 1,2,4,5-Tetracyan-3,6-dijodbenzol (20).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19761090713
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