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  • 1975-1979  (6,318)
  • 1977  (6,318)
  • Chemistry  (5,684)
  • Cell & Developmental Biology  (573)
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  • 101
    Electronic Resource
    Electronic Resource
    Kinetic analysis of the reversible folding reactions of small proteins: Application to the folding of lysozyme and cytochrome c (1977)
    New York : Wiley-Blackwell
    Biopolymers 16 (1977), S. 731-747 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A general kinetic analysis for unimolecular three-species models is presented. Criteria are established for each model in order to allow selection among alternative models on the basis of their amplitude behavior. These criteria are applied to the previously reported kinetic data for the folding transitions of lysozyme and cytochrome c in guanidine hydrochloride. The degree of success in applying these criteria is found to depend on the extent to which the apparent rate constants, λ1 and λ2, approach each other in certain conditions. Ikai and Tanford have presented a similar kinetic analysis, although these authors considered only the case where no intermediate kinetic species was populated initially. For one protein system, namely, ribonuclease A (RNase A), at least one stable intermediate exists after unfolding outside of the equilibrium transition zone. The criteria developed by Ikai and Tanford cannot be applied to RNase A kinetics and, therefore, a more general analysis is presented. Previously published studies of the reversible folding kinetics of lysozyme and cytochrome c are reexamined using the current amplitude analysis, and it is found that both of these folding transitions can be described by the three-species model, \documentclass{article}\pagestyle{empty}\begin{document}$$ U_{1} \rightleftharpoons U \rightleftharpoons N $$\end{document} used previously to describe the folding kinetics of RNase A (U1 and U2 are two forms of unfolded enzyme and N is the native species). These results suggest that this three-species model may provide a fairly general description of the reversible folding kinetics of small proteins. As an outgrowth of the current analysis, several suggestions for experimental design in studying protein folding will be presented and discussed.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1977.360160404
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  • 102
    Electronic Resource
    Electronic Resource
    Reduction of ferriprotoporphyrin IX to the ferroderivative by copoly(4-vinylpyridine-N-(p-vinylbenzyl)-3-carbamoyl-1,4-dihydropyridine) in dimethyl sulfoxide (1977)
    New York : Wiley-Blackwell
    Biopolymers 16 (1977), S. 845-855 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The copolymer which has both ligand sites (4-vinylpyridine) and redox sites (N-(p-vinylbenzyl)-3-carbamoyl-1,4-dihydropyridine) was synthesized by the dithionite reduction of the copoly(4-vinylpyridine-N-(p-vinylbenzyl)-3-carbamoylpyridinium chloride) and the reduction of a central ferric-iron of ferriprotoporphyrin IX by the above-described copolymer was studied spectrophotometrically in dimethyl sulfoxide. The rate of the reduction by the copolymer was much faster than by N-benzyl-3-carbamoyl-1,4-dihydropyridine. This acceleration by the copolymer could be explained by the intramolecular reduction of ferriprotoporphyrin IX which was coordinated by the pyridine residue of the copolymer.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1977.360160409
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  • 103
    Electronic Resource
    Electronic Resource
    On the B to A conformation change of the double helix (1977)
    New York : Wiley-Blackwell
    Biopolymers 16 (1977), S. 965-982 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We have investigated the B to A conformation change of DNA double helices by a new method “soft-mode analysis.” We find theoretically that a mode does soften when the vibration normal modes are perturbed by increasing the electrostatic interaction between the unbalanced charges on atoms in the double helix. The same mode also softens for enhanced van der Waals interactions. The mode softening indicates the onset of conformation change. The enhancing of the electrostatic and van der Waals interaction mimic the effect of decreasing the polar nature of the solvent or water of hydration associated with the B conformation DNA. We discuss qualitatively the concept of soft modes and their relation to conformation change as well as their applicability to macromolecules. We discuss previous work in which the normal vibrational modes have been calculated. We also discuss the displacement which comes from the soft mode and show that it correlates very well with that expected for the B to A conformation charge.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1977.360160503
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  • 104
    Electronic Resource
    Electronic Resource
    Quantitative electron microscope observations of the collagen fibrils in rat-tail tendon (1977)
    New York : Wiley-Blackwell
    Biopolymers 16 (1977), S. 1015-1031 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An electron microscope study of collagen fibrils from fixed tail tendons of rats has revealed that from some time shortly after birth until maturity, the fibril diameters have a bimodal distribution. The “two” types of fibril are indistinguishable in both transverse and longitudinal section. Unfixed specimens of eight-week-old-tail tendon showed a similar bimodal distribution of diameters though the positions of the peak values compared to fixed specimens of an eight-week-old-tail tendon were shifted upwards by about 30%. It has also been shown quantitatively that the polar collagen fibrils are directed randomly “up” and “down” with respect to their neighbors. Whilst it has been suggested by others that anastomosis is a feature of collagen structure, the results presented here do not support this hypothesis. Fibrillar units ∼ 140 Å in diameter have been observed and the possibilities that these are elastic fibers or the breakdown products of collagen fibrils have been considered.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1977.360160506
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  • 105
    Electronic Resource
    Electronic Resource
    The organization and repair of DNA in the mammalian chromosome. II. A gradient-shape-induced speed dependence affecting DNAs larger than T4 DNA (1977)
    New York : Wiley-Blackwell
    Biopolymers 16 (1977), S. 1083-1092 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The addition of a lytic layer to a preformed linear sucrose gradient induces a temporary (up to half a day) initial gradient of considerable steepness which retards the sedimentation of large (〉T4) DNAs. Centrifugation at sufficiently slow angular velocities permits the temporary initial gradient to disappear and therefore the sedimentation distance increases, yielding a rotor speed dependent effect on sedimentation distance. Gradients which are free of this effect are described and shown to permit mouse leukemia cell DNA to sediment independently of rotor speed (5-30 krpm).
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1977.360160510
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  • 106
    Electronic Resource
    Electronic Resource
    Helix coil transitions of d (A)n·d(T)n, d(A-T)n·d(A-T)n, and d(A-A-T)n·d(A-T-T)n; evaluation of parameters governing DNA stability (1977)
    New York : Wiley-Blackwell
    Biopolymers 16 (1977), S. 1115-1137 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The thermally induced helix-coil transitions of three A-T DNAs, d(A)n·d(T)n, d(A-T)n·d(A-T)n, and d(A-A-T)n·d(A-T-T)n, were studied. Experimental transition curves of the DNAs were analyzed using the loop entropy model of DNA melting. The calculation of the melting curve of d(A-A-T)n·d(A-T-T)n is presented using the integral equation formalism of Goel and Montroll. The aim of this work was to evaluate thermodynamic parameters which govern DNA stability and to test the theoretical model employed in the analysis. Our results show (1) an excellent over-all agreement between theory and experiment, (2) a loop entropy exponent k = 1.55 ± 0.05 provided the best fit to all the polymer transition curves, (3) the evaluated stacking free energies reflect the relative stability of the DNAs, and (4) the stacking energies of the ApA·TpT dimer evaluated from d(A)n·d(T)n and d(A-A-T)n·d(A-T-T)n differ. The last result is consistent with different conformations for the dimer in these two polymers.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1977.360160512
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  • 107
    Electronic Resource
    Electronic Resource
    1H nuclear magnetic resonance studies of N-acetyl-L-proline N-methylamide. Molecular conformations, hydrogen bondings, and thermodynamic quantities in various solvents (1977)
    New York : Wiley-Blackwell
    Biopolymers 16 (1977), S. 1259-1270 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Concentration and temperature dependences of the 1H nmr spectra of N-acetyl-L-proline N-methylamide were observed in various solvents [CCl4, CDCl3, (CD3)2CO, (CD3)2SO, H2O, and D2O]. The fraction of the cis isomer (with respect to the bond between the acetyl carbonyl carbon and prolyl nitrogen atoms) depends greatly on the solvent used; the fraction of the cis isomer is higher in polar solvents than in nonpolar solvents. It depends also on concentration and temperature in nonpolar solvents but not in polar solvents. In nonpolar solvents the trans isomer mostly exists in the γ-turn structure with an intramolecular hydrogen bond and the cis isomer tends to form molecular aggregates by intermolecular hydrogen bonds. In polar solvents both the cis and trans isomers exist in monomeric forms which interact with solvent molecules. The pH dependences of the N-methyl proton resonances indicate that the γ-turn structure of the trans isomer is present also in aqueous solution, though its population is difficult to determine. Apparent enthalpy and entropy changes for the conversion of the trans isomer to cis isomer are evaluated for various solvents. The results are discussed in terms of the intra- and intermolecular hydrogen bondings.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1977.360160608
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  • 108
    Electronic Resource
    Electronic Resource
    On nonequivalent intermolecualar stagger states in collagen fibrils (1977)
    New York : Wiley-Blackwell
    Biopolymers 16 (1977), S. 1357-1361 
    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.1977.360160615
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  • 109
    Electronic Resource
    Electronic Resource
    X-Ray analysis of bovine pancreatic ribonuclease analogs: A difference Fourier at 2.8 Å resolution of (O r n10)-ribonuclease S′ (1977)
    New York : Wiley-Blackwell
    Biopolymers 16 (1977), S. 1371-1376 
    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.1977.360160618
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  • 110
    Electronic Resource
    Electronic Resource
    Synthesis and carbon-13 nuclear magnetic resonance spectra of Cyclo(D-leucyl-L-leucine) and Cyclo(L-leucyl-L-leucine) (1977)
    New York : Wiley-Blackwell
    Biopolymers 16 (1977), S. 1387-1395 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cyclo(D-Leu-L-Leu) and cyclo(L-Leu-L-Leu) were synthesized, and their carbon-13 nmr spectra at 65 MHz were examined in dimethylsulfoxide and trifluoroacetic acid solutions. The chemical shift data are consistent with a boat or “twisted” boat conformation of the diketopiperazine ring in both solvents. There was no indication of protonation of the cyclic dipeptides by trifluoroacetic acid. Attempts at polymerizing the cyclic dipeptides were unsuccessful.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1977.360160702
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  • 111
    Electronic Resource
    Electronic Resource
    Interactions of highly charged colloidal cylinders with applications to double-stranded DNA (1977)
    New York : Wiley-Blackwell
    Biopolymers 16 (1977), S. 1435-1448 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This paper presents new applications of the McMillan-Mayer solution theory to dispersions of highly charged colloidal cylinders in monovalent salt solutions. The thermodynamic solution properties are given in terms of the virial expansions relating to a Donnan membrane equilibrium. General expressions are derived for the second Donnan pressure virial coefficient B2 and for the first two salt distribution coefficients A1 and A2. The effect of electric interactions is represented as an increased effective diameter dB or dA of the colloidal cylinder. This yields the simple excluded volume expressions B2 = πdBL2/4 and A1 = πdA2L/4 for hard cylinders of length L and diameter dB and dA, respectively. The coefficient A2 is derived from the dependence of B2 on the salt concentration.Computations are made for double-stranded DNA in sodium chloride solutions with the DNA model developed in the preceding paper: a uniformly charged cylinder, with size and charge consistent with transport experiments, and surrounded by a Gouy double layer. In 1-0.005M sodium chloride solutions dB is found to vary from 29 Å to about 220 Å, and dA from 30 Å to about 170 Å, with little sensitivity to the uncertainties in the kinetic diameter d ≈ 24 Å and the experimental ζ potentials of DNA. Corresponding results predicted by the classical Donnan theory are 6-167 times too high for B2.Values of A2 are relatively small, in line with the expected rapid convergence of the virial expansion for the salt distribution. This is consistent with a phase transition from random to parallel orientation of the cylinders predicted first by Onsager for hard cylinders on the basis of B2, but not yet observed for DNA in simple salt solutions.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1977.360160705
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  • 112
    Electronic Resource
    Electronic Resource
    Calorimetric investigation of some elastin-solvent systems (1977)
    New York : Wiley-Blackwell
    Biopolymers 16 (1977), S. 1505-1512 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The interaction of ox ligamentum nuchae elastin (native, purified, and soluble) with different solvents (water, ethylene glycol, methanol, and 2,2,2-trifluoroethanol) was investigated by means of differential scanning calorimetry. The unfreezable solvent content and the corresponding solvent to elastin residue molar ratio were determined from the melting endotherms of the freezable solvent present in these systems. The molar ratio obtained in the case of water and ethylene glycol agrees with hypothesis of a direct solvation of the main chain peptide group and is interpreted according to a model previously proposed for polyamides. Quite different molar ratios are obtained in the case of the two monofunctional solvents and no model can be proposed at present to explain their interaction with the protein.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1977.360160710
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  • 113
    Electronic Resource
    Electronic Resource
    Helix-coil stability constants for the naturally occurring amino acids in water. XII. Asparagine parameters from random poly(hydroxybutylglutamine-co-L-asparagine) (1977)
    New York : Wiley-Blackwell
    Biopolymers 16 (1977), S. 1567-1585 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis and characterization of water-soluble random copolymers containing L-asparagine with N5-(4-hydroxybutyl)-L-glutamine, and the thermally induced helix-coil transitions of these copolymers in water, are described. The incorporation of L-asparagine was found to decrease the helix content of the polymers in water at all temperatures. The Zimm-Bragg parameters σ and s for the helix-coil transition in poly(L-asparagine) in water were deduced from an analysis of the copolymer melting curves in the manner described in earlier papers. The computed values of s indicate that asparagine destabilizes helical sequences at all temperatures in the range 0-60°C.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1977.360160715
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  • 114
    Electronic Resource
    Electronic Resource
    Synthesis and conformational study of poly(0,0′-dicarbobenzoxy-L-β-3,4-dihydroxyphenyl-α-alanine) (1977)
    New York : Wiley-Blackwell
    Biopolymers 16 (1977), S. 1593-1607 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: High-molecular-weight poly(0,0′-dicarbobenzoxy-L-β-3,4-dihydroxyphenyl-α-alanine) was prepared by the N-carboxyanhydride method. From the results obtained by a study of the optical rotation, nuclear magnetic resonance, and solution infrared absorption, the conformation of poly(0,0′-dicarbobenzoxy-L-β-3,4-dihydroxyphenyl-α-alanine) depended greatly on the solvent taking a right-handed helix with [θ]225 = -13,600 ∼ -18,900 in alkyl halides, a left-handed helix with [θ]228 = 22,100 ∼ 24,800 in cyclic ethers or trimethylphosphate, and a random coil structure in dichloroacetic acid, trifluoroacetic acid, or hexafluoroacetone sesquihydrate. The polypeptide underwent a right-handed helix-coil transition in chloroform/dichloroacetic acid (or trifluoroacetic acid) mixed solvents and a left-handed helix-coil transition in dioxane/dichloroacetic acid (or trifluoroacetic acid) mixed solvents. The results were compared with those of poly(0-carbobenzoxy-L-tyrosine).
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1977.360160717
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  • 115
    Electronic Resource
    Electronic Resource
    Unsaturated amino-acid residues as probes for the conformation of polypeptides in solution (1977)
    New York : Wiley-Blackwell
    Biopolymers 16 (1977), S. 1677-1686 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Acetyl-(dehydro-Phe) and acetyl-bis(dehydro-Phe) groups have been attached to the ε-amino group of the lysine residues of the copolymer poly(Glu92Lys8) by reacting this last with acetyl-(dehydro-Phe)-azlactone and acetyl-bis(dehydro-Phe)-azlactone, respectively.In the latter case induced CD is observed between 250 and 330 nm, due to the relative dissymmetric disposition of the two dehydro-Phe groups under the chiral field of the polypeptide chain.pH dependence of the induced CD, observed for the copolymer and lacking in the lowmolecular-weight structural model, is related to the α-helical and random coiled conformation of the polypeptide chain.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1977.360160806
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  • 116
    Electronic Resource
    Electronic Resource
    The dichroic tensor of flexible helices (1977)
    New York : Wiley-Blackwell
    Biopolymers 16 (1977), S. 2143-2165 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A statistical theory of the linear dichroism of DNA-like chains is presented for two models which are discrete versions of the wormlike coil. In the final form the linear dichroism of the entire chain is related directly to the dichroic properties of a chain segment (base pair). Though the derivations are somewhat complicated, the result [Eq. (28)] is simple and the required statistical parameters can be easily calculated for either model from measured values of the persistence length. In fact, for molecules as stiff as double-stranded DNA, the results can be reduced with good accuracy to the form \documentclass{article}\pagestyle{empty}\begin{document}$$ \frac{{\Delta \varepsilon (chain)}}{{\Delta \varepsilon (segment)}} = \frac{{P_{\infty} }}{l}\frac{r^{2}}{{\langle r^2 \rangle_0 }} $$\end{document} showing that the “optical persistence” given on the left is directly proportional to the structural persistence, P∞/l. As in previous theories the results are restricted to chains in their Gaussian limit.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1977.360161006
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  • 117
    Electronic Resource
    Electronic Resource
    Histidine-containing cyclic dipeptides as catalysts in the hydrolysis of carbonic acid p-nitrophenyl esters (1977)
    New York : Wiley-Blackwell
    Biopolymers 16 (1977), S. 2203-2215 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A histidine-containing cyclic dipeptide, cyclo(D-Leu-L-His), was almost 20 times as efficient a catalyst as imidazole in the hydrolysis of p-nitrophenyl laurate. The effect of dioxane on the hydrolysis showed that hydrophobic interaction between the cyclic dipeptide and the ester is very important. This reaction obeyed the Michaelis-Menten kinetics, and the Michaelis constant Km was as low as 9.98 × 10-5M. Since the linear dipeptide having D-Leu-L-His sequence was nearly inactive in the hydrolysis, the functional groups of cyclo(D-Leu-L-His) in a specific arrangement held by the rigid backbone must have cooperated in the fast hydrolysis. Very weak catalysis by the diasteremeric cyclic dipeptide, cyclo(L-Leu-L-His), in the hydrolysis supported the above view.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1977.360161009
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  • 118
    Electronic Resource
    Electronic Resource
    Alexander von Humboldt (1769-1859) (1977)
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 11 (1977), S. 14-21 
    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.19770110103
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  • 119
    Electronic Resource
    Electronic Resource
    Die Olefin-Metathese (1977)
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 11 (1977), S. 22-27 
    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.19770110104
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  • 120
    Electronic Resource
    Electronic Resource
    Masthead (1977)
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 11 (1977) 
    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.19770110201
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  • 121
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    Isomerie. LaborBücher Chemie. Von H. Daecke. Verlag Moritz Diesterweg/Otto Salle Verlag, Frankfurt/M., und Verlag Sauerlander, Aarau 1976. 1. Aufl., XI, 115 S., zahlr. Abb. geb. DM 19,80 (1977)
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 11 (1977), S. 28-29 
    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.19770110108
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  • 122
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    mini-chiuz. Europäische Kooperation in der Didaktik der Naturwissenschaften (1977)
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 11 (1977), S. A4 
    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.19770110111
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  • 123
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    Struktur und Verhalten von Molekülen im Raum. Von G. Natta und M. Farina. Übersetzt von P Schmid. Verlag Chemie GmbH, Weinheim/B., New York 1976. 1. Aufl., VIII, 248 S., 132 Abb., 8 Tab., brosch. DM 38, - (1977)
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 11 (1977), 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.19770110206
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  • 124
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    Rompps Chemie-Lexikon. Von O.-A. Neumüller. Franckh'sche Verlagshandlung, W. Keller & Co, 7. Auflage, Band 1-6, Stuttgart 1972-1977. Geb. DM 160,-pro Band (1977)
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 11 (1977), S. 64-64 
    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.19770110210
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  • 125
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    Mikroorganismen als organische Chemiker (1977)
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 11 (1977), S. 75-82 
    Details
    ISSN: 0009-2851
    Keywords: Chemistry ; Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ciuz.19770110303
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  • 126
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    Intensivkurs Mathematik. Programmierte Prüfung für das Selbststudium. [taschentext 54]. Von W. Schmidt. Verlag Chemie GmbH, Weinheim, New York 1976. 1. Aufl., 185 S., 44 Abb., 1 Tab., 4 Ausklapptafeln, geb. DM 16,80 (1977)
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 11 (1977), S. 94-94 
    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.19770110306
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  • 127
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    Chronik (1977)
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 11 (1977), S. 197-198 
    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.19770110606
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  • 128
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    Masthead (1977)
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 11 (1977) 
    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.19770110401
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  • 129
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    Chronik (1977)
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 11 (1977), S. 129-130 
    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.19770110405
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  • 130
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    Quecksilber - ein Problemelement für den Menschen?? (1977)
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 11 (1977), S. 150-156 
    Details
    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.19770110504
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  • 131
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    Chemie und Biologie der Eisen-Schwefel-Proteine (1977)
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 11 (1977), S. 165-175 
    Details
    ISSN: 0009-2851
    Keywords: Chemistry ; Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ciuz.19770110602
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  • 132
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    Dehydrobenzol: ein (metallorganisches) Stabilisierungsproblem (1977)
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 11 (1977), S. 190-196 
    Details
    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.19770110605
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  • 133
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    mini-chiuz (1977)
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 11 (1977), S. A80 
    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.19770110607
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  • 134
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    Intermolecular indole-imidazolium complexes. II. Interaction of a block copolymer (L-tryptophan)n-(γ-ethyl-DL-glutamate)m with imidazolium hydrochloride and poly(L-histidine hydrochloride) (1977)
    New York : Wiley-Blackwell
    Biopolymers 16 (1977), S. 109-119 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The charge-transfer complexes of a poly(L-tryptophan) sequence with imidazolium hydrochloride and poly(L-histidine hydrochloride) have been investigated in 2,2,2-trifluoroethanol by ultraviolet (uv), circular dichroism (CD), and fluorescence techniques. Both complexes exhibit absorption maxima centered at around 275 nm, whereas hypochromism with respect to the combined spectra of the constituents can be observed below 250 nm. All complexes show optical activity in the near uv and in the peptide absorption region, which is discussed in terms of the conformational properties of the donor. A marked decrease of the fluorescence intensity of the L-tryptophan sequence is observed upon addition of imidazolium hydrochloride and poly(L-histidine hydrochloride). From the fluorescence data the formation constant of the charge-transfer complex between the L-tryptophan sequence and imidazolium ions is also evaluated.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/bip.1977.360160109
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  • 135
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    Solid-state infrared absorption spectra and chain arrangement in some synthetic homooligopeptides in the intermolecularly hydrogen-bonded pleated-sheet β-conformationThis work is part 34 of a series; for part 33 see Ref. 1. (1977)
    New York : Wiley-Blackwell
    Biopolymers 16 (1977), S. 219-224 
    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.1977.360160116
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  • 136
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    Masthead (1977)
    New York : Wiley-Blackwell
    Biopolymers 16 (1977) 
    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.1977.360160201
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  • 137
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    The interaction of carboxymethylamylose and diethylaminoethylamylose with iodine (1977)
    New York : Wiley-Blackwell
    Biopolymers 16 (1977), S. 983-1006 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Spectrophotometric titrations of slightly substituted carboxymethylamylose (CM-Amy) and diethylaminoethylamylose (DEAE-Amy) with iodine in the presence of iodide (I2/I-) were carried out as a function of iodide concentration, temperature, and polymeric charge. Binding isotherms for the polymer-I2/I- complex are reported in terms of an apparent binding constant (Ka) plotted versus degree of saturation of the complex (θ). The dependence of Ka upon polymeric charge is interpreted as evidence for the negatively charged character of the bound species. The cooperative nature of the binding process is evident in the positive slope of Ka vs (θ). Whereas the apparent binding constants and binding cooperativities for the derivatives are smaller than for the amylose-I2/I- complex, the binding enthalpies deduced from the temperature dependence of Ka at θ = 0.5 appear to be the same for amylose and CM-Amy. A viscometric titration of fully charged CM-Amy with I2/I-, conducted at dialysis equilibrium between the CM-Amy-I2/I- solution and the polymer-free solvent phase, disclosed a maximum in the plot of intrinsic viscosity ([η]) vs θ. The increase in [η] at small θ was interpreted as a reflection of polyelectrolyte expansion provoked by absorption of the negatively charged bound species; the subsequent decline in [η] is attributed to stabilization by I2/I- of compact helical sequences or to the formation at higher θ of intermolecular aggregates.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/bip.1977.360160504
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  • 138
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    The effect of ions on the enzymatic properties of beef-liver glutamate dehydrogenaseThis paper has been described in a preliminary report [G. Blauer & H. Sund (1975) Abstr. Commun. 10th Meet. Fed. Eur. Biochem. Soc., Société de Chimie Biologique, Paris, No. |706]. The preceding paper in this series, “Studies of |Glutamate Dehydrogenase,” is by R. Koberstein, L. Cobianchi & H. Sund (1976) FEBS Lett. 64, 176-180. (1977)
    New York : Wiley-Blackwell
    Biopolymers 16 (1977), S. 1053-1061 
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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: The effect of various salts on the enzymatic activity of beef-liver glutamate dehydrogenase, on the binary enzyme-reduced coenzyme (NADH or NADPH) comples, as well as on the ternary complex with glutamate was investigated in aqueous solution (0.067M phosphate buffer, pH 7.6). Binding studies in the analytical ultracentrifuge and circular dichroism measurements indicated dissociation of the coenzyme from the enzyme-coenzyme complex by the action of various salts. The efficiency of this change was largely dependent on the type of anion present and generally followed the series: acetate 〈 Br- 〈 I- 〈 SCN-. Acetate ions and guanidinium thiocyanate showed exceptional behaviour in some cases, while K+ and Na+ gave similar results. The reversibility of the ion effects on the enzymatic activity was demonstrated by dilution tests. Upon addition of salts, the inhibitory effect of GTP was slightly changed in most cases, while the activating effects of ADP and L-leucine were practically abolished and with ADP, the halides caused an additional inhibition. Assuming an equilibrium involving dissociation of the enzyme-coenzyme complex by the action of salts, an exponent of 1.3 for NaBr and of 2.0 for KSCN was calculated for the respective concentrations. The apparent equilibrium constants were evaluated to be about 20 times greater for KSCN than for NaBr.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/bip.1977.360160508
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  • 139
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    Synthesis and characterization of four sequential glycyl/glutamate polypeptides (1977)
    New York : Wiley-Blackwell
    Biopolymers 16 (1977), S. 1139-1151 
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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: Poly(Glu(OBzl)-Gly)n, poly(Glu-Gly)n, poly(Gly)-(Glu(OBzl)-Gly), and poly(Gly-Glu-Gly) were synthesized from the pentachlorophenyl esters of the sequential monomer. Both of the polymers containing free glumatic-acid residues are soluble in water, as is the lower molecular weight fraction of the polytripeptides with the benzyl ester in place. Circular dichroism studies and infrared dichroism studies suggest that the 21 helix is favored for the polydipeptide with removal of the benzyl ester reducing the conformational integrity. The polytripeptide showed evidence of 31 helix in addition to the 21 form, depending on solvent. A rationale for the conformations observed is developed based on the bulkiness of the side-chain residues and conformational stabilization, in certain cases, by hydrophobic interactions between the benzyl ester groups.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/bip.1977.360160513
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  • 140
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    Elastin as a rubber (1977)
    New York : Wiley-Blackwell
    Biopolymers 16 (1977), S. 1201-1222 
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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: The thermoelastic behavior of water solvated elastin has been investigated in simple tension, in the temperature range 0-70°C. Specimens purified from both the ox ligamentum nuchae and pig thoracic aorta have been studied. Force data obtained by cycling the temperature for various constant specimen lengths display a separated variable dependence of the form f = A(T)B(α), where T is absolute temperature and α the extension ratio. For ligament elastin B(α) is a linear function whereas for aortic elastin it is a nonlinear function. The applicability of the rubber elasticity theory to elastin has been tested by setting A(T) equal to the temperature-dependent front factor for simple tension of a homogeneous rubber whilst B(α) is left undefined. In this way it has been possible to take into account the fibrous nonhomogeneity of the polymer, and also to avoid any inconsistency within the theory of attributing a dependence of the variable fe/f upon extension ratio. The behavior of both ligament and aortic elastin agrees well with the conclusion that the dominant deformation mechanism is entropy elastic, fe/f ≪ 1. The linearity of the load isotherm for ligament elastin permits a particularly simple experimental procedure using a single force-temperature plot for one value of interclamp length. Using this procedure high precision has been obtainble, and the data shows a close adherence to the theory with fe/f = 0.1. The relationship between this result and current controversy over the molecular conformation of elastin is discussed.
    Additional Material: 9 Ill.
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    URL: http://dx.doi.org/10.1002/bip.1977.360160604
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  • 141
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    Analysis of periodic patterns in amino acid sequences: Collagen (1977)
    New York : Wiley-Blackwell
    Biopolymers 16 (1977), S. 1271-1297 
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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: Methods are given for analyzing regularly spaced patterns of amino acids in proteins and applied to the α1 chain of collagen. Fourier methods use the transform of the sequence either embedded in a very long array or folded onto a fundamental base period. Filtering through a moveable “window” of definite width is used to display almost regular features at any chosen frequency. A pattern detection method is described for patterns of general shape. Collagen has statistically significant periodicities at fractions of the stagger distance D = 670 Å. Hydrophobic groups show strong orders of 5, 6, 11; proline 5; charged groups 6, 18, 21. Charged residues mostly occur as neutral pairs. Their distribution has strong 6th and 21st orders which also appear in the changes which are paired at multiples of D. Charge pairs separated by (D + 3) residues show a strong 5D/89 pattern and may form a system of salt bridges across the fibril. There is no sign of any regular pattern of amino acids over the triple helix with a period close to its natural pitch of 30 residues. Supercoiled models with six relative turns of the contact edge between paired triple-helical strands are examined.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/bip.1977.360160609
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  • 142
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    Conformational changes induced in ionized poly(L-arginine) and poly(L-histidine) by sodium dodecyl sulfate (1977)
    New York : Wiley-Blackwell
    Biopolymers 16 (1977), S. 1319-1329 
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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: Circular dichroism spectra have been obtained for cationic poly(L-arginine) and poly(L-histidine) in aqueous solutions containing varying amounts of sodium dodecyl sulfate. The detergent induces a disorder-order transition in both polypeptides. In each case the transition is cooperative and occurs when the ratio of detergent to amino acid residue is near unity. The ordered structure formed by poly(L-arginine) is readily identifiable as an α helix. Poly(L-histidine) appears to form a β structure in which the 211-nm electronic absorption band of the imidazole group exhibits significant rotatory strength.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/bip.1977.360160612
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  • 143
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    Circular dichroism evidence for G·U and G·T base pairing in poly[r(G-U)] and poly[d(G-T)] (1977)
    New York : Wiley-Blackwell
    Biopolymers 16 (1977), S. 1331-1342 
    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 circular dichroism (CD) and absorption properties of poly[r(G-U)] and poly [d(G-T)] over a wide range of Na+ concentrations and temperatures. We find evidence for self-complexed forms of these polymers at lower temperatures and/or higher Na+ concentrations than generally needed for double-strand formation in other DNA and RNA polymers. These self-complexes could be composed of double-stranded regions with weak G·U or G·T base pairs.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/bip.1977.360160613
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  • 144
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    Electric birefringence studies of cartilage proteoglycan aggregation (1977)
    New York : Wiley-Blackwell
    Biopolymers 16 (1977), S. 1367-1369 
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    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.1977.360160617
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  • 145
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    Influence of local interactions on protein structure. I. Conformational energy studies of N-acetyl-N′-methylamides of pro-X and X-pro dipeptides (1977)
    New York : Wiley-Blackwell
    Biopolymers 16 (1977), S. 1385-1385 
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    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.1977.360160620
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  • 146
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    The interaction of 8-anilino-1-naphthalenesulfonate with polylysine and polyarginine (1977)
    New York : Wiley-Blackwell
    Biopolymers 16 (1977), S. 1449-1464 
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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: Comparative studies on the interaction of 8-anilino-1-naphthalenesulfonate (ANS) with polylysine and polyarginine have been made by equilibrium dialysis and fluorescence or circular dichroism measurements, to investigate the structural characteristics of the polypeptides. The results are summarized as follows: (i) ANS binds to either of the polypeptides primarily by electrostatic interaction while hydrophobic interaction partially facilitates the dye binding; both interactions are stronger in the polyarginine-dye binding than the polylysine-dye binding. (ii) The fluorescence of ANS is more intensified when the dye binds to polyarginine than to polylysine regardless of the value of r (number of bound dye per amino-acid residue) of polypeptide-dye complexes, although the intensification depends on the r value and becomes maximum at r = 0.25-0.35 for both cases. (iii) The binding of ANS to each polypeptide is cooperative at r 〈 0.4. (iv) The circular dichroism is more efficiently induced in the spectral region of ANS by binding to polyarginine than to polylysine.From these results, it was concluded that, compared to polylysine, polyarginine suffers some structural change by ANS binding into a more compact molecular configuration having some regularity with a lower dielectric environment.
    Additional Material: 12 Ill.
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    URL: http://dx.doi.org/10.1002/bip.1977.360160706
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  • 147
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    Circular dichroism of adenine and thymine containing synthetic polynucleotides (1977)
    New York : Wiley-Blackwell
    Biopolymers 16 (1977), S. 1489-1504 
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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: Circular dichroism (CD) spectra of poly(dA), poly(dT), poly(dA)·poly(dT), and poly[d(A-T)]·poly[d(T-A)] have been measured as a function of temperature. From these data difference spectra have been calculated by subtracting the spectrum measured at low temperature from the spectra measured at higher temperatures. The CD difference spectra obtained upon melting of the two double-stranded polymers are very similar. From a comparison of these difference spectra with calculated ones it is shown that optical transitions near 272 nm (on A) and 288 nm (most probably on T) are present. The premelting changes of the CD spectrum of poly[d(A-t)]·poly[d(T-A)] are due to a change in conformation in which the secondary structure goes from a C- to B-type spectrum by increasing the A-type nature of the polymer. Such a change is not observed for poly(dA)·poly(dT). Instead, a transition between two different B-type geometries occurs.
    Additional Material: 10 Ill.
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    URL: http://dx.doi.org/10.1002/bip.1977.360160709
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  • 148
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    Poly(L-lysyl-L-alanyl-α-L-glutamic acid). II. Conformational studies (1977)
    New York : Wiley-Blackwell
    Biopolymers 16 (1977), S. 1527-1540 
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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: The solution characterization of poly(Lys-Ala-Glu) is described. This polytripeptide is zwitterionic at neutral pH and is shown to take on a conformation which is dictated by the state of ionization, molecular weight, temperature, and solvent. The polypeptide is almost entirely α-helical at low pH and temperature for polymers of greater than 25,000 molecular weight. Melting profiles for these conditions show tm ∼ 20°C. Analysis of circular dichroism curves shows the α-helical content to vary in a linear manner with molecular weight in the range 3000-30,000. At neutral pH the charged polypeptide is essentially random, but substantial α-helix could be induced by addition of methanol or trifluoroethanol. At temperatures where the sequential polypeptide is a random coil, addition of trifluoroethanol produces a polymer which is mostly α-helical but also contains an appreciable ammount of β-structure. The infrared spectrum of a low-molecular-weight fraction assumed to be cyclo(Lys-Ala-Glu)2 was tentatively assigned a β-pleated sheet structure.A comparison of this polytripeptide in various ionization states with other polytripeptides containing L-alanine and L-glutamate or L-lysine shows the α-helix directing properties for the (uncharged) residues to lie in the order Ala 〉 Glu 〉 Lys.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/bip.1977.360160712
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  • 149
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    Helix-coil stability constants for the naturally occurring amino acids in water. XIII. The presence of by-products in amino-acid analysis of copolymers and their effect on the guest parameters; recomputed values of σ and s for L-serine (1977)
    New York : Wiley-Blackwell
    Biopolymers 16 (1977), S. 1587-1592 
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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: Previously used procedures for processing the amino acids from 6N hydrochloric acid hydrolysis of poly[N5-(4-hydroxybutyl)-L-glutamine], poly[N5-(3-hydroxypropyl)-L-glutamine], and several random copolymers derived from these, led to the formation of spurious products. These have been isolated and characterized as the γ-ester of glutamic acid and the hydroxyalkyl amine, and chloro-alkyl amine hydrochloride. The former reduces the observed values for glutamic acid, but the latter has no effect on them. A method is used to avoid formation of these artifacts in the amino-acid analysis. Of all the copolymers studied previously in this series, the compositions of only those containing L-serine are in error as a result of the formation of the γ-ester. A redetermination of the amino-acid compositions of the copolymer fractions studied earlier leads to slightly revised values for the Zimm-Bragg parameters σ and s of serine.
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    URL: http://dx.doi.org/10.1002/bip.1977.360160716
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    Helix-coiled transition in heteropolymers. I. Ground-state energy (1977)
    New York : Wiley-Blackwell
    Biopolymers 16 (1977), S. 1657-1675 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new technique is presented for treating the ground state of an heteropolymer with a random sequence of components. An exact system of equations is found for determining the ground state energy E which is equal to the polymer free energy f in the lowest-order approximation in T/V (V/2 is the large “surface” energy arising at the boundaries between coiled and “helical” sections: V ≫ T, Uk; U1 and -U2 are the free energies of the components counted from the corresponding coiled state energies). These equations are essentially simplified at certain fixed values of the ratio U1/U2. For integer values of U2/U1 and U1/U2 a solution is obtained with an accuracy exp(-V/Uk). The ground-state energy as a function of U1 and U2 is shown to be highly irregular: its derivatives have jumps at an infinite number of points. These jumps provide a fine structure of the melting curves. A smoothed over the jumps function E′ is found by way of analytic continuation from the integer values of U1/U2 and U2/U1. The accuracy of the approximation f ≈ E is estimated and the correctional term of order T/V is determined.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/bip.1977.360160805
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  • 151
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    Nuclear magnetic resonance study of the impact of ribose 2′-O-methylation on the aqueous solution conformation of cytidylyl-(3′ → 5′)-cytidine (1977)
    New York : Wiley-Blackwell
    Biopolymers 16 (1977), S. 1687-1711 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In order to obtain information about the conformational characteristics at the nearestneighbor level in the 2′-O-methylated region of t-RNA, as well as in the bizarre 5′-terminus of eucaryotic mRNA, a detailed nuclear magnetic resonance study of 2′-O-methyl-cytidylyl-(3′ → 5′)-cytidine (CmpC) was conducted. Proton spectra were recorded at 270 MHz in the Fourier mode in D2O solutions, 0.01M, pD 7.3 in the temperature range 5-80°C. Complete accurate sets of nmr parameters were derived for each of the nucleotidyl units by a combination of homo-nuclear decouplings and simulation iteration methods. The data were translated into conformational parameters using procedures developed in earlier studies from these laboratories.It is shown that the ribofuranose ring exists at a 2E ⇄ 3E equilibrium with clear preference [(75-80)%] for the 3E mode. The C(4′)-C(5′) and C(5′)-O(5′) bonds form a stable conformational network with outspoken preference for conformers in which Ψ1, Ψ2 ≃ 60° and φ2 ≃ 180°. The orientation of the 3′-phosphate and 2′-O-methyl groups is such that φ1′ ≃ 210° and φ″ ≃ 60°. The phosphodiester bonds are flexible and shift trends for base, H(1′), and H(5″) suggest the existence of a conformational blend of right-handed stack (g-g-), left-handed stack (g+g+), and unstacked arrays (tg- and tg+).Elevation of temperature perturbs the 2E ⇄ 3E equilibrium accompanied with modest depopulation of ψ1, ψ2 ≃ 60° and φ2 ≃ 180° conformers. The major effect of elevation of temperature is in the increase of unstacked arrays at the expense of g-g- and g+g+ conformers. The shift trend of Cmp-H(3′) with temperature shows that torsional variation about O(3′)-P is facilitated by increase in temperature and the preferred rotamer about O(3′)-P in the unstacked form is t (ω1′ = 180°).A detailed comparison of the aqueous solution conformations of CpC and CmpC reveals that 2′-O-methylation causes: (i) a reduction in the magnitude of χ1; (ii) an increase in the population of 3E pucker at the 3′-nucleotidyl unit; and (iii) modest perturbations in the O(3′)-P and P-O(5′) bond conformations. Comparison of the aqueous solution conformations of AmpA and CmpC makes clear that the conformational properties of pyrimidine-pyrimidine and purine-purine dimers which carry a 2′-O-methylated 3′-nucleotidyl unit are significantly different.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/bip.1977.360160807
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    Poly(L-lysyl-L-alanyl-α-L-glutamic acid)All amino acid are L unless designated otherwise. Other abbreviations are: Dnp, 2,4-dinitrophenyl; Boc, t, butyloxycarbonyl; Cbz, carbobenzoxy; -ONSu, N-hydroxysucinimide ester; Mr, molecular weight; Mw, weight-average moleculer weight; Mn, number-average molecular weight; Mz, z-average molecular weight. (1977)
    New York : Wiley-Blackwell
    Biopolymers 16 (1977), S. 1513-1525 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Poly(Lys(Cbz)-Ala-Glu(OBzl)) was prepared by the self-condensation of Lys(Cbz)-Ala-Glu(OBzl)-ONSu in dimethylformamide. After deprotection of the side chains, the product was subjected to Sephadex G-50 chromatography. The molecular weight of unfractionated and fractionated poly(Lys-Ala-Glu) was calculated from a calibrated Sephadex G-50 column, spectrophotometrically from Dnp-(Lys-Ala-Glu), equilibrium centrifugation, and viscosity measurements. Approximately 21% of the unfractionated material was polymeric with the remaining 79% being cyclic and monomeric material. Treatment of polymer hydrolysate with L-amino acid and D-amino acid oxidase indicated poly(Lys-Ala-Glu) to be optically pure. The apparent pKa's of the two ionizable groups were 4.1 and 9.7.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/bip.1977.360160711
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  • 153
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    Kinetics of the renaturation of yeast tRNA3Leu (1977)
    New York : Wiley-Blackwell
    Biopolymers 16 (1977), S. 1557-1566 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Yeast tRNA3Leu is one of several tRNA molecules which can adopt a stable, biologically inactive, denatured conformation. The circular dichroism of the native and denatured conformers differs, providing the basis for the present study of the mechanism for the renaturation process. Conversion of the denatured structure to the native takes place in two steps: a rapid change occurring immediately on addition of Mg++, followed by a slower, strongly temperature-dependent step which returns the molecule to its biologically active state. Optimal kinetic data for the second step could be obtained at 285 nm. Analysis of the time dependence of Δε285 by the Guggenheim method demonstrated that this step follows first-order kinetics. The temperature dependence of the rate constants over the range 32-41°C yielded the following parameters for the rate-limiting step: Ea = 69 kcal/mole, ΔH
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/bip.1977.360160714
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  • 154
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    Helical segment analysis of α-helical regions in proteins (1977)
    New York : Wiley-Blackwell
    Biopolymers 16 (1977), S. 1617-1634 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The methods suggested earlier for the analysis and representation of protein structural data are now extended to the helical regions in finer details. These enable better handling of characterization of bends and distortions, for which statistical parameters are also developed. Using latest myoglobin data, best experimental parameters for the α-helix are deduced to be rN = 1.55 (0.13) Å, rCα = 2.28 (0.12) Å, rC′ = 1.70 (0.10) Å, r0 = 2.02 (0.12) Å, φ = 100.5 (2.3)°, and t = 1.495 (0.055) Å.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/bip.1977.360160803
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  • 155
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    d-CpCpGpG and d-GpGpCpC self-complementary duplexes: Nmr studies of the helix-coil transition (1977)
    New York : Wiley-Blackwell
    Biopolymers 16 (1977), S. 1635-1656 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We have monitored the helix-coil transition of the self-complementary d-CpCpGpG and d-GpGpCpC sequences (20mM strand concentration) at the base pairs, sugar rings, and backbone phosphates by 360-MHz proton and 145.7-MHz phosphorus nmr spectroscopy in 0.1M phosphate solution between 5 and 95°C. The guanine 1-imino Watson-Crick hydrogen-bonded protons, characteristic of the duplex state, are observed below 10°C, with solvent exchange occurring by transient opening of the tetranucleotide duplexes. The cytosine 4-amino Watson-Crick hydrogen-bonded protons resonate 1.5 ppm downfield from the exposed protons at the same position in the tetranucleotide duplexes, with slow exchange indicative of restricted rotation about the C-N bond below 15°C. The guanine 2-amino exchangeable protons in the tetranucleotide sequence exhibit very broad resonances at low temperatures and narrow average resonances above 20°C, corresponding to intermediate and fast rotation about the C-N bond, respectively. Solvent exchange is slower at the amino protons compared to the imino protons since the latter broaden out above 10°C. The well-resolved nonexchangeable base proton chemical shifts exhibit helix-coil transition midpoints between 37 and 42°C. The transition midpoints and the temperature dependence of the chemical shifts at low temperatures were utilized to differentiate between resonances located at the terminal and internal base pairs while the H-5 and H-6 doublets of individual cytosines were related by spin decoupling studies. For each tetranucleotide duplex, the cytosine H-5 resonances exhibit the largest chemical shift change associated with the helix-coil transition, a result predicted from calculations based on nearest-neighbor atomic diamagnetic anisotropy and ring current contributions for a B-DNA duplex. There is reasonable agreement between experimental and calculated chemical shift changes for the helix-coil transition at the internal base pairs but the experimental shifts exceed the calculated values at the terminal base pairs due to end-to-end aggregation at low temperatures. Since the guanine H-8 resonances of the CpCpGpG and d-CpCpGpG sequences exhibit upfield shifts of 0.6-0.8 and 〈0.1 ppm, respectively, on duplex formation, these RNA and DNA tetranucleotides with the same sequence must adopt different base-pair overlap geometries. The large chemical shift changes associated with duplex formation at the sugar H-1′ triplets are not detected at the other sugar protons and emphasize the contribution of the attached base at the 1′ position. The coupling sum between the H-1′ and the H-2′ and H-2″ protons equals 15-17 Hz at all four sugar rings for the d-CpCpGpG and d-GpGpCpC duplexes (25°C), consistent with a C-3′ exo sugar ring pucker for the deoxytetranucleotides in solution. The temperature dependent phosphate chemical shifts monitor changes in the ω,ω′ angles about the O-P backbone bonds, in contrast to the base-pair proton chemical shifts, which monitor stacking interactions.
    Additional Material: 12 Ill.
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    URL: http://dx.doi.org/10.1002/bip.1977.360160804
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  • 156
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    Extrinsic cotton effect and helix-coil transition in a DNA-polycation complex (1977)
    New York : Wiley-Blackwell
    Biopolymers 16 (1977), S. 1713-1724 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A strong, positive, extrinsic CD band ([θ]242.5 = ∼2 × 10-3 deg cm2/dmole) has been observed for a α-bromo-poly[methylene-1,4-phenylenecarbonyloxyethylene(dimethylamino) bromide] (I). The extrinsic Cotton effect is attributed to the ordered arrangement of the aromatic chromophores along the DNA helix.The extrinsic band had a linear dependence on the amount of polycation I added from r ≤ 0.3 to r = ∼0.5, but decreased thereafter. Addition of the polycation decreased the positive CD band of DNA at 275 nm. The transformation of B → C form in the presence of salts or other polycations caused similar changes. The decrease in [θ]275 was reversed at higher concentrations of the polycation (r 〉 0.4).Thermal denaturation studies indicated both stabilization of the helix conformation (Δtm = 21°C) and a high degree of cooperativity in the melting of DNA-polycation complex as compared to native calf thymus DNA. Using the linear relationship between r (polycation residue/DNA phosphate) and F (fraction of bound base pairs), a value of 0.6 was derived for β (number of monomer residues of polycation/nucleotide).Both electrostatic and hydrophobic effects probably influence the stability of the DNA-polycation complex, since the strength of the 242.5 nm CD band is a function of both salt and urea concentrations.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/bip.1977.360160808
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  • 157
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    Temperature-jump experiments on the acridine orange-poly(α-L-glutamic acid) system in the low NaCl concentration region - aggregation process of acridine orange on poly(Glu) (1977)
    New York : Wiley-Blackwell
    Biopolymers 16 (1977), S. 1827-1832 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1977.360160816
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    13C and 1H NMR studies of helix-coil transition of poly(β-benzyl-L-aspartate) and poly(γ-benzyl-L-glutamate): Behavior in nonprotonating solvent mixtures, and origin of solvent-induced chemical shift (1977)
    New York : Wiley-Blackwell
    Biopolymers 16 (1977), S. 2521-2532 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: From the results of 13C-nmr measurement of poly(β-benzyl-L-aspartate) and its model compounds in dimethyl sulphoxide/deuterated chloroform mixtures, it was found that the side chain of poly(β-benzyl-L-aspartate) is solvated by dimethyl sulphoxide in the region more than dimethyl sulphoxide 20% (v/v), where the backbone maintains the α-helix. The chemical shift differences in the benzyl group carbons of poly(γ-benzyl-L-glutamate) (trifluoroacetic acid/deuterated chloroform) accompanied by the helix-coil transition, originate from the interaction between the ester group of the side chain and trifluoroacetic acid. The chemical shift difference in the ester carbon is similar. On the other hand, the chemical shift differences of the side-chain carbons in the alkyl portion (Cβ, Cγ) originate not only from the interaction between the ester group of the side chain and trifluoroacetic acid, but also from some other unknown factors. The chemical shift differences of the side-chain carbons of poly(β-benzyl-L-aspartate) originate from the interaction between the ester group of the side chain and trifluoroacetic acid.
    Additional Material: 9 Ill.
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    URL: http://dx.doi.org/10.1002/bip.1977.360161114
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    Circular dichroism of protein and glycoprotein fish antifreezes (1977)
    New York : Wiley-Blackwell
    Biopolymers 16 (1977), S. 2575-2578 
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    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.1977.360161119
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    Masthead (1977)
    New York : Wiley-Blackwell
    Biopolymers 16 (1977) 
    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.1977.360161201
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  • 161
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    Decomposition of hydrogen peroxide by configurationally different Fe(III) complexes supported on poly(L-glutamate) (1977)
    New York : Wiley-Blackwell
    Biopolymers 16 (1977), S. 2569-2573 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    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/bip.1977.360161118
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  • 162
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    Synthesis of a cyclic analog of the luteinizing hormone releasing factor: LRF (1977)
    New York : Wiley-Blackwell
    Biopolymers 16 (1977), S. 2587-2590 
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    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.1977.360161121
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  • 163
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    A 310-Helix in poly(α-aminoisobutyric acid) (1977)
    New York : Wiley-Blackwell
    Biopolymers 16 (1977), S. 2591-2592 
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    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.1977.360161122
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  • 164
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    Influence of temperature and ionic strength on the low-frequency dielectric dispersion of DNA solutions (1977)
    New York : Wiley-Blackwell
    Biopolymers 16 (1977), S. 2653-2669 
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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: The dielectric properties of DNA solutions at low frequencies (5 Hz to 2 kHz) have been measured by means of a four-terminal bridge method utilized to minimize electrode polarization errors. At 24°C native salt-free DNA has a very large specific dielectric increment, Δε/c = 9.8 × 106 l/mol and a very low frequency relaxation centered at 18 Hz. Both the dielectric increment and the relaxation time are greatly decreased by partial heat denaturation at temperatures above 60°C or by addition of salt, the effects being much larger for divalent anions. These results are shown to be in qualitative agreement with theoretical treatments of counterion fluctuation polarization by McTague and Gibbs for the equilibrium case and by Mandel for relaxation. The ratio of the relaxation time for the low-frequency process to that previously observed at much higher frequencies suggests that these relaxations result from counterion fluctuations along the longitudinal and transverse axes of the molecule, respectively.
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    URL: http://dx.doi.org/10.1002/bip.1977.360161207
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  • 165
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    Intrachain reactions of a pair of reactive groups attached to polymer ends. V. Formation of disulfide linkages in the air-oxidation of sulfhydryl groups attached to ends of polysarcosine chain (1977)
    New York : Wiley-Blackwell
    Biopolymers 16 (1977), S. 2723-2738 
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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: Polysarcosine having sulfhydryl groups attached to both ends was synthesized by the NCA method and its air-oxidation was investigated in aqueous solution with cupric-ion or ferric-ion catalysts. Air-oxidation was also conducted for a polysarcosine having one terminal sulfhydryl group. The product of the air-oxidation was fractionated by gel chromatography. The product analysis of the fully oxidized monofunctional polymer showed that the sulfhydryl groups were converted into disulfide bonds exclusively. There was no evidence for the interchange between two disulfide linkages or between a disulfide linkage and a sulfhydryl group during the air-oxidation. The analysis of the products from the bifunctional polysarcosine showed that they were composed of a series of cyclic “monomer,” “dimer,” “trimer,” and higher “oligomers.” The cyclic structure was characterized by the larger elution volume in the gel chromatogram than that for a linear homologue having the same molecular weight. The weight fraction of each cyclic oligomer was determined by gel chromatography. The fraction of cyclic monomer F1 decreased monotonously with increasing the chain length. Smaller values of F1 were observed with cupric-ion catalyst than with ferric-ion catalyst. The dependence of F1 on the polymer concentration was much smaller than that expected from a simple competition mechanism between intra- and intermolecular reactions. These results indicate that the choice between intra- and intermolecular reactions is governed by the mode of the coordination of sulfhydryl groups to transition metal ions.
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    Scattering correction to the absorbance, wavelength dependence of the refractive index increment, and molecular weight of the bovine liver glutamate dehydrogenase oligomer and subunits (1977)
    New York : Wiley-Blackwell
    Biopolymers 16 (1977), S. 2773-2783 
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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: The wavelength dependence of the refractive index increments of bovine serum albumin and bovine liver glutamate dehydrogenase solutions was determined in the range 650-300 nm. It was shown, by measuring the extinction coefficients of glutamate dehydrogenase under conditions of widely differing molecular weights, that a significant scattering correction need not be applied to correct extinction measurements in the absorbtion band. The molecular weight of glutamate dehydrogenase oligomer determined by light scattering and sedimentation equilibrium agrees with the value calculated from the primary structure, if a recently reported value of the extinction coefficient is used.
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    URL: http://dx.doi.org/10.1002/bip.1977.360161214
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  • 167
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    Masthead (1977)
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 11 (1977) 
    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.19770110101
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    Lehrprogramm Atombau und Periodensystem. [taschentext 47]. Von Christa Braig. Verlag Chemie GmbH, Weinheim 1976 1. Aufl., X, 144 S., 40 Abb., 2 Ausklapptafeln, Br. DM 12,80 (1977)
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 11 (1977), S. 28-28 
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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.19770110105
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  • 169
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    Succinimidbildung bei der Synthese des Insulin-A-Ketten(14-21)-Octapeptids (1977)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 110 (1977), S. 1-11 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Formation of Succinimide During the Synthesis of the Insulin A Chain(14-21) OctapeptideDuring the synthesis of insulin A chain (14-21) fragments it was observed that alkaline treatment of Msc-Cys(Trt)-Asn-OBut, Msc-Leu-Glu(OBut)-Asn-Tyr(But)-Cys(Trt)-Asn-OBut and Msc-Tyr-(But)-Gln-Leu-Glu(OBut)Asn-Tyr(But)-Cys(Trt)-Asn-OBut caused quantitative formation of succinimide in position 21.
    Notes: Bei der Synthese von Teilsequenzen der Insulin-A-Kette (14-21) wurde während der alkalischen Abspaltung der Msc-Gruppe von Msc-Cys(Trt)-Asn-OBut, Msc-Leu-Glu(OBut)-Asn-Tyr(But)-Cys-(Trt)-Asn-OBut und Msc-Tyr-(But)-Gln-Leu-Glu(OBut)-Asn-Tyr(But)-Cys(Trt)-Asn-OBut in allen Fällen Succinimidbildung in Position 21 beobachtet.
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    URL: http://dx.doi.org/10.1002/cber.19771100102
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    Carben-Reaktionen, IX. Zur Reaktion von Amidacetalen mit Heterocumulenen (1977)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 110 (1977), S. 37-48 
    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, IX. On the Reaction of Amide Acetals with HeterocumulenesDeprotonation of the (dimethylamino)methoxycarbenium ion (10) by NaH liberated the carbene 2, which was trapped by aryl isocyanate to give the hydantoin 6 and by phenyl isothiocyanate to yield 8. Hence, the carbene 2 is assumed to be also an intermediate in the corresponding reactions of the amide acetal 1 which lead to the hydantoins 6 and 8. The reaction of 1 with phenyl isothiocyanate yielded the products 4, 7, 8, or 12 depending on the reaction conditions. An equilibrium between 1 and the carbene 2 is suggested by the reaction of 1 with sulfur to give 16, and is the basis for mechanistic discussions.
    Notes: Das durch Deprotonierung des (Dimethylamino)methoxy-carbenium-Ions (10) mit NaH freigesetzte Carben 2 addierte sich an-Arylisocyanat zum Hydantoin 6, an Phenylisothiocyanat zu 8. Dies legt nahe, daß auch bei der Umsetzung des Amidacetals 1 mit Heterocumulenen zu den Hydantoinen 6 bzw. 8 das Carben 2 beteiligt ist. Bei der Umsetzung von 1 mit Phenylisothiocyanat entstanden je nach Reaktionsführung die Produkte 4, 7, 8 oder 12. Für deren Bildung werden Mechanismen diskutiert, die von einer Gleichgewichtseinstellung von 1 mit dem Carben 2 ausgehen. Diese Annahme wird durch Umsetzung von 1 mit Schwefel zu 16 gestützt.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19771100105
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  • 171
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    Perhalogenmethylthio-Heterocyclen, VIII. (Perchlorfluormethylthio)- und (Halogenformylthio)-N-Heteroaromaten (1977)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 110 (1977), S. 67-77 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: (Perhalomethylthio)heterocycles, VIII. (Perchlorofluoromethylthio)- and (Haloformylthio)-N-heteroaromaticsPyrrole reacts with Cl3-nFnC—SCl (n = 1-3) to give mixtures of 2- and 3-substituted pyrroles 1 a-c and 2a, b; CF3SCFCl—SCl and XC(O)SCl (X = F, Cl) merely yield 2-substituted derivatives 3. In the presence of excess CF3SCl also disubstituted products 4, 5 are available. Analogously pyrrole derivatives can be substituted directly, dependent on their reactivity (6-14). 1a is oxidized by 3-chloroperbenzoic acid to yield the sulfoxide 15 or the sulfone 16; the reaction with bromine and iodine results in the formation of the fully halogenated compounds 17, 18. Indole reacts with CF3SCl to give the 3-substituted 19, while carbazole yields the N-substituted product 20 in a Grignard reaction. 1H and 19F n. m. r. spectra are discussed.
    Notes: Pyrrol setzt sich mit Cl3-nFnC—SCl (n = 1-3) zu Isomerengemischen 2- und 3-substituierter Pyrrole 1a-c bzw. 2a, b, um; CF3SCFCl—SCl und XC(O)SCl (X = F, Cl) liefern lediglich 2-substituierte Derivate 3. In Gegenwart eines CF3SCl-Überschusses sind auch disubstituierte Produkte 4, 5 erhältlich. Analog sind Pyrrol-Derivate, je nach ihrer Reaktivität, einer direkten Substitution zugänglich (6-14). 1 a wird durch 3-Chlorperbenzoesäure zum Sulfoxid 15 bzw. Sulfon 16 oxidiert; die Umsetzung mit Brom bzw. Iod führt zu den vollständig halogenierten Verbindungen 17, 18. Indol reagiert mit CF3SCl zum 3-substituierten 19, während Carbazol in einer Grignard-Reaktion das N-Substitutionsprodukt 20 liefert. 1H- und 19F-NMR-Spektren werden diskutiert.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19771100108
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  • 172
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    Zur Reaktion des Makosza-Reagens mit Aldehyden und Ketonen (1977)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 110 (1977), S. 96-106 
    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 Aldehydes and Ketones with the Makosza Dichlorocarbene ReagentPhase transfer-catalyzed reactions of aldehydes and ketones with trichloromethane and 50 per cent aqueous sodium hydroxide in the presence of benzyltriethylammonium chloride (BTEA) at low temperatures result in the formation of α-(trichloromethyl)carbinols 7; in the presence of dimethyl sulfate the corresponding methyl ethers 8 are obtained. At 56 ± 2°C the α-hydroxy-11, α-chloro- 12 and α,β-unsaturated carboxylic acids 13 are formed. In this reaction the α-(trichloromethyl)carbinols 7 can be excluded as intermediates. An alternative reaction mechanism for the formation of 11, 12, and 13 is discussed, which involves direct addition of dichlorocarbene to the C=O double bond to form the dichlorooxiranes 5 followed by rearrangement and saponification.
    Notes: Aldehyde und Ketone reagieren mit Trichlormethan im Zweiphasensystem mit 50proz. wäßrigem Natriumhydroxid unter Phasentransfer-Katalyse durch Benzyltriethylammonium-chlorid (BTEA) (1) bei tiefer Temperatur zu α-(Trichlormethyl)carbinolen 7, in Gegenwart von Dimethylsulfat zu den entsprechenden Methylethern 8. Bei 56 ± 2°C entstehen α-Hydroxy- 11, α-Chlor- 12 und α,β-ungesättigte Carbonsäuren 13, wobei die α-(Trichlormethyl)carbinole 7 als Zwischen-stufen auszuschließen sind. Als Alternativmechanismus wird die direkte Addition von Dichlor-carben an die C=O-Doppelbindung zu Dichloroxiranen 5 und deren Umlagerung und Verseifung diskutiert.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19771100111
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  • 173
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    Masthead (1977)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 110 (1977) 
    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.19771100101
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  • 174
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    Carben-Reaktionen, VIII. Selektivität nucleophiler Carbene gegenüber Heterocumulenen (1977)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 110 (1977), S. 23-36 
    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, VIII. Selectivity of Nucleophilic Carbenes with Regard to HeterocumulenesThe selectivities of N-methylbenzothiazolinylidene (2) and 1,3-diphenylimidazolidinylidene (3) against aryl isocyanates and phenyl isothiocyanate have been determined. The selectivities increase from dimethoxycarbene (1) over 2 to 3. In contrast all three carbenes display equal selectivity with regard to different aryl isocyanates.
    Notes: Für N-Methylbenzothiazolinyliden (2) und 1,3-Diphenylimidazolidinyliden (3) wurden die Selektivitäten gegenüber verschiedenen Arylisocyanaten einerseits und Phenylisothiocyanat andererseits bestimmt. Diese nehmen vom Dimethoxycarben (1) über 2 zu 3 zu. Dagegen zeigen alle drei Carbene bei 140°C eine übereinstimmende Selektivität gegenüber Arylisocyanaten.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19771100104
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  • 175
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    Untersuchungen an Stoffwechselprodukten von Mikroorganismen, XII. Michigazon, ein neues Phenoxazon aus Streptomyces michiganensis  -  Konstitutionsermittlung und Synthese (1977)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 110 (1977), S. 12-22 
    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 Metabolites of Microorganisms, XII. Michigazone, a New Phenoxazone Pigment from Streptomyces michiganensis  -  Structure Determination and SynthesisBy spectroscopic methods and chemical degradation michigazone has been shown to possess structure 7. 7 and some further related phenoxazones have been synthesized by the Kehrmann-method.
    Notes: Spektroskopische Untersuchungen und chemischer Abbau führten für Michigazon zur Konstitution 7. 7 und einige weitere bisher noch nicht beschriebene Phenoxazone wurden durch Kehrmann-Synthese dargestellt.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19771100103
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  • 176
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    Carben-Reaktionen, X. Ionische Zwischenstufen der Reaktion von Orthoameisensäure-trimethylester mit Arylisocyanat (1977)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 110 (1977), S. 49-52 
    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, X. Ionic Intermediates in the Reaction of Trimethyl Orthoformate with Aryl IsocyanatesThe ion pair 2/3 is assumed to be the crucial intermediate in the reaction of trimethyl orthoformate with aryl isocyanates. The collapse of the ion pair to 4 is a fast subsequent reaction. The acid base reaction of the ion pair to the carbene 6 proceeds with a comparable rate. Methoxyl transfer of 2/3 to form 1 is considerably slower. Transalkylation of the ion pair to 8 has not been observed.
    Notes: Bei der Umsetzung von Orthoameisensäure-trimethylester mit Phenylisocyanat wird das Ionen-paar 2/3 als zentrale Zwischenstufe angenommen. Eine rasche Folgereaktion dieses Ionenpaares ist die Kombination zu 4. Vergleichbar schnell verläuft die Säure-Basen-Reaktion im Ionenpaar zum Carben 6. Eine Methoxyl-Übertragung aus 2/3 zu 1 ist erheblich langsamer. Die Umalkylierung zu 8 konnte nicht beobachtet werden.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19771100106
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  • 177
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    Aktivierte Ethylene, V. Umsetzung von Aromaten mit Chlormethylenmalonsäure-Derivaten. Eine neue Synthese aromatischer Aldehyde (1977)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 110 (1977), S. 86-95 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Activated Ethylenes, V. Reaction of Aromatic Compounds with Derivatives of Chloromethylenemalonic Acid. A new Synthesis of Aromatic AldehydesThe derivatives of chloromethylenemalonic acid 3 and 4 react with aromatic compounds in the presence of aluminium chloride to give the arylmethylenemalonic acid derivatives 5a-i and 6a-d. By hydrolysis of the C=C double bond the corresponding dinitriles 2a-g are converted into aldehydes.
    Notes: Chlormethylenmalonsäure-Derivate 3 und 4 lassen sich in Gegenwart von Aluminiumchlorid mit Aromaten umsetzen, wobei die Arylmethylenmalonsäure-Derivate 5a-i und 6a-d entstehen. Die entsprechenden Dinitrile 2a-g lassen sich durch Hydrolyse der C=C-Doppelbindung in Aldehyde überführen.
    Additional Material: 8 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19771100110
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  • 178
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    Zur Stereochemie der Norcaradien-Norcaradien-Umlagerung, I. Die Synthese optisch aktiver [Norcaradien ⇌ Cycloheptatrien]-Derivate (1977)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 110 (1977), S. 107-123 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Stereochemistry of the Norcaradiene-Norcaradiene Rearrangement, I. The Synthesis of Optically Active [Norcaradiene ⇌ Cycloheptatriene] DerivativesAnion 14 derived from treatment of 1,3,5-cycloheptatriene-7-carbonitrile (13) with n-butyllithium or lithium diisopropyl reacts with methyl iodide, deuterium oxide, and carbon dioxide to give the corresponding 7,7-disubstituted derivatives 2, 13-D, and 16. By a sequence of reactions 2 was transformed into the optically pure [norcaradiene ⇌ cycloheptatriene] systems 4 and 10. The equilibrium concentrations of the [norcaradiene ⇌ cycloheptatriene] systems 2-12 were determined by 1H n.m.r. mesurements at low temperatures.
    Notes: Das aus 1,3,5-Cycloheptatrien-7-carbonitril (13) mit n-Butyllithium oder Lithium-diisopropylamid erzeugte Anion 14 reagiert mit Methyliodid, Deuteriumoxid und Kohlendioxid ausschließlich zu den entsprechenden 7,7-disubstituierten Derivaten 2, 13-D, und 16. Aus 2 lassen sich durch eine Folge von Reaktionen die optisch reinen [Norcaradien ⇌ Cycloheptatrien]-Systeme 4 und 10 synthetisieren. Mit Hilfe der Tieftemperatur-1H-NMR-Spektroskopie wurden die Gleichgewichtskonzentrationen der [Norcaradien ⇌ Cycloheptatrien]-Systeme 2-12 ermittelt.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19771100112
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  • 179
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    Reaktionen mit 4-Acetoxy-2-cyclopenten-1-on (1977)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 110 (1977), S. 146-153 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reactions with 4-Acetoxy-2-cyclopenten-1-oneBy using 4-acetoxy-2-cyclopenten-1-one (8) as a synthone for the non-existent cyclopentadienone (5), Michael additions are performed that give rise to trans-disubstituted cyclopentanone derivatives (11,12). In the case of tert-butyl acetoacetate as Michael donator the addition to 11 is followed by an aldol-cyclisation to the trans-perhydroazulene system 22.
    Notes: Unter Verwendung von 4-Acetoxy-2-cyclopenten-1-on (8) als Synthon für das nicht existenzfähige Cyclopentadienon (5) wurden Michael-Additionen durchgeführt, die zu trans-disubstituierten Cyclopentanon-Derivaten (11, 12) führen. Bei Verwendung von tert-Butyl-acetacetat als Michael-Donator schließt sich an die Addition zu 11 eine Aldolcyclisierung zum trans-Perhydroazulensystem 22 an.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19771100115
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  • 180
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    Reaktionen mit 3,3-Bis(trifluormethyl)-Δ4-1,4,2λ5-oxazaphospholinen. Abfangreaktionen von Nitril-yliden mit Nitrosobenzol (1977)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 110 (1977), S. 605-610 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reactions with 3,3-Bis(trifluoromethyl)-Δ4-1,4,2λ5-oxazaphospholines. Trapping Reactions of Nitrile Ylides with NitrosobenzeneTrapping reactions of bis(trifluoromethyl)-substituted nitrile ylides 2, generated by thermolysis of 3,3-bis(trifluoromethyl)-Δ4-1,4,2λ5-oxazaphospholines. 1, with nitrosobenzene yield 5,5-bis-(trifluoromethyl)-Δ3-1,2,4-oxadiazolines 3, 3,3-bis(trifluoromethyl)-Δ4-1,2,4-oxadiazolines 4, and 4,4-bis(trifluoromethyl)-1,4-dihydro-1-quinazolinols 5. The compounds 5 are products of a thermal rearrangement of first formed [3 + 2]-cycloadducts. I. r., 1H n. m. r., 19F n. m. r., and mass spectra of the new compounds are described.
    Notes: Abfangreaktionen von bis(trifluormethyl)-substituierten Nitril-yliden 2, die durch Thermolyse aus 3,3-Bis(trifluormethyl)-Δ4-1,4,2λ5-oxazaphospholinen 1 erzeugt werden, mit Nitrosobenzol liefern 5,5-Bis(trifluormethyl)-Δ3-1,2,4-oxadiazoline 3, 3,3-Bis(trifluormethyl)-Δ4-1,2,4-oxadiazoline 4 und 4,4-Bis(trifluormethyl)-1,4-dihydro-1-chinazolinole 5. Die Verbindungen 5 sind das Resultat einer thermisch ausgelösten Umlagerung primär erhaltener [3 + 2]-Cycloaddukte. IR-, 1H-NMR-, 19F-NMR- und Massenspektren der neuen Verbindungen werden beschrieben.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19771100221
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  • 181
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    Zur Konjugation in makrocyclischen Bindungssystemen, XXIV. Benzo[12]annulene: Über den Annulen-Charakter von Dibenzo-und Tribenzo[12]annulenen (1977)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 110 (1977), S. 619-630 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Conjugation in Macrocyclic Systems, XXIV. Benzo[12]annulenes: On the Annulene Character of Dibenzo- and Tribenzo[12]annulenesAs a contribution to the controversial discussion about the antiaromaticity of the [12]annulene system in the di- and tribenzo[12]annulenes 3 and 4 the compounds 5, 8, and 18 were prepared for comparison. The discussion of the 1H n. m. r. spectra with consideration of the anisotropy effect of the triple bonds led to the conclusion that in contrast to earlier assumptions the [12]annulene system in 3 and 4 in spite of the benzo-anellation is paratropic.
    Notes: Als Beitrag zu der kontroversen Diskussion über die Antiaromatizität des [12]Annulen-Systems in den Di- und Tribenzo[12]annulenen 3 und 4 wurden die Vergleichsverbindungen 5, 8 und 18 dargestellt. Die Diskussion der 1H-NMR-Spektren unter Berücksichtigung des Anisotropieeffektes der Dreifachbindungen ergab, daß entgegen früherer Auffassung das [12]Annulen-System in 3 und 4 trotz der Benzo-Anellierung paratrop ist.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19771100223
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    Zur Konjugation in makrocyclischen Bindungssystemen, XXV. Benzo[12]annulene: Synthese und Eigenschaften eines Benzo-naphtho[12]annulens (1977)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 110 (1977), S. 631-637 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Conjugation in Macrocyclic Systems, XXV. Benzo[12]annulenes: Synthesis and Properties of a Benzo-naphtho[12]annuleneThe benzo-naphtho[12]annulene 4, where in contrast to 1, 2, and 3 a planar twelve-membered ring is present, has been synthesized via 6-9. 1H n. m. r. absorption of the internal hydrogen is observed at δ = 13.13 ppm. The allotment of this considerable down-field shift to the paratropic effect of the annulene system and the anisotropy of the triple bonds is discussed. For this purpose, the twelve-ring system 5 in which the macrocyclic conjugation is interrupted has been synthesized from 9 via 10 and 11.
    Notes: Das Benzo-naphtho[12]annulen 4, bei dem im Gegensatz zu den Verbindungen 1, 2 und 3 eine ebene Zwölfring-Struktur fixiert ist, wurde über 6-9 synthetisiert. Die 1H-NMR-Absorption des inneren Wasserstoffatoms wird bei δ = 13.13 ppm beobachtet. Die Aufteilung dieser beträchtlichen Tieffeld-Verschiebung in den Paratropie-Effekt des Annulen-Systems und den Anisotropie-Effekt der Dreifachbindungen wird diskutiert. Hierzu wurde das Zwölfring-System 5, bei dem die makrocyclische Konjugation unterbrochen ist, von 9 über 10 und 11 synthetisiert.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19771100224
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  • 183
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    1,3-Anionische Cycloadditionen, XV. Reaktionen von trans,trans-1,3-Diphenyl-2-azaallyllithium mit Heterokumulenen (1977)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 110 (1977), S. 651-655 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: 1,3-Anionic Cycloadditions, XV. Reactions of trans,trans-1,3-Diphenyl-2-azaallyllithium with Heterocumulenestrans,trans-1,3-Diphenyl-2-azaallyllithium (1) reacts with phenylisocyanate, phenylisothiocyanate, and methylisothiocyanate to give an imidazolidine-4-one (2a) or imidazolidine-4-thione (2b, c), respectively. When reacting with carbon disulfide or dicyclohexylcarbodiimide (symmetrical heterocumulenes) the cycloaddition is followed by a fast secondary reaction (→ 4, 7).
    Notes: trans,trans-1,3-Diphenyl-2-azaallyllithium (1) cycloaddiert sich regiospezifisch an die CN-Doppel-bindung des Phenylisocyanats sowie Phenyl- und Methylisothiocyanats unter Bildung eines Imidazolidin-4-ons (2a) bzw. -4-thions (2b, c). Bei entsprechenden Umsetzungen mit den symmetrischen Heterokumulenen Schwefelkohlenstoff und Dicyclohexylcarbodiimid folgt der Cycloaddition jeweils eine schnelle Sekundärreaktion (→4, 7).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19771100227
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  • 184
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    Reaktionen von trans-[Pt(CO2R)(CO)(PPh3)2] +BF4- mit Alkinen: Bildung von Alkinyl- und Alkenylplatin(II)-Komplexen (1977)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 110 (1977), S. 667-676 
    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 trans-[Pt(CO2R)(CO)(PPh3)2]+BF4- with Alkynes: Formation of Alkynyl- and Alkenylplatinum(II) ComplexesThe alkoxycarbonyl complexes [Pt(CO2R)(CO)(PPh3)2]+ BF4- 1 react with alkynes HC≡CR to give the acetylides 2a-c. On the other hand, cationic β-methoxyvinyl 3 or β-hydroxyvinyl complexes 4, respectively, are obtained from the reactions of 1 with disubstituted acetylenes R1C≡CR2 under participation of the nucleophiles methanol and water. Compounds 3 and 4 are converted into neutral derivatives (5, 6, 8) by methoxide or azide ions. The synthesis of Ir(CO2CH3)(CO)(CH3O2CC≡CCO2CH3)[P(CH3)Ph2]2 is described. Bonding is discussed for the new complexes by means of n. m. r. and i. r. data.
    Notes: Die Alkoxycarbonyl-Komplexe [Pt(CO2R)(CO)(PPh3)2]+BF4- 1 setzen sich mit Alkinen HC ≡ CR zu den Acetyliden 2a-c um. Dagegen entstehen aus 1 und disubstituierten Acetylenen R1C≡CR2 unter Beteiligung der Nucleophile Methanol und Wasser kationische β-Methoxyvinyl- 3, bzw. β-Hydroxyvinyl-Komplexe 4. Die Verbindungen 3 und 4 werden mit Methylat- oder Azid-Ionen in neutrale Derivate (5, 6, 8) umgewandelt. Ferner wird die Synthese von Ir(CO2CH3)(CO)-(CH3O2CC≡CCO2CH3)[P(CH3)Ph2]2 beschrieben. Die Bindungsverhältnisse werden mit Hilfe von NMR- und IR-Daten diskutiert.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19771100229
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    Zweifach überbrückte 5,6-Diamino-4,7-dialkyl-1,3-benzodioxole als Zwischenprodukte zur Synthese von Molekülen mit Knotenstruktur (1977)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 110 (1977), S. 703-716 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Double Bridged 5,6-Diamino-4,7-dialkyl-1,3-benzodioxoles as Intermediates for the Synthesis of Molecules with Knot StructureIn a reaction sequence involving metalation with butyllithium followed by alkylation. cyclohexanone pyrocatechol acetal 4 is converted to the 3,6-dialkylpyrocatechol 11. By subsequent acetalisation with 1,25-dichloro-13-pentacosanone (14), followed by nitration (19), reduction (20), acylation (26), renewed reduction (27), and cyclization, the double bridged benzodioxole 28 is obtained. The compound represents an intermediate in the projected synthesis of a molecule with knot structure.
    Notes: Ausgehend vom Cyclohexanon-brenzcatechinacetal 4 wird durch Metallierung mit Butyllithium und nachfolgende Alkylierung in einer mehrstufigen Reaktionsfolge das 3,6-Dialkylbrenzcatechin 11 synthetisiert. Durch nachfolgende Acetalisierung mit 1,25-Dichlor-13-pentacosanon (14), gefolgt von Nitrierung (19), Reduktion (20), Acylierung (26), erneuter Reduktion (27) und Cyclisierung wird das zweifach überbrückte Benzodioxol 28 erhalten. Es stellt ein Zwischenprodukt in der geplanten Synthese eines Moleküls mit Knotenstruktur dar.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19771100233
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  • 186
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    Gezielte Synthese von Sulfinato-O- und -S-Komplexen einiger Übergangsmetalle, XIV. Sulfinato-O,S-Komplexe von Palladium(II) und Rhodium(III) (1977)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 110 (1977), S. 463-467 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Directed Synthesis of Sulfinato-O and -S Complexes of Some Transition Metals, XIV Sulfinato-O,S Complexes of Palladium(II) and Rhodium(III)The directed preparation of the sulfinato-O,S complexes {R(O)OS}nM (2a, b; 5a, b) was successful for the first time by elimination of coordinated water from the sulfinato-S complexes {RS(O)2}nM(OH2)n [n = 2, M = Pd (1a, b); n = 3, M = Rh (4a, b)] by 2,2-dimethoxypropane. The O,S-linkage is unequivocally shown from their chemical behaviour and the i. r. spectra. The criteria necessary for the formation of sulfinato-O,S complexes are discussed.
    Notes: Durch Abspaltung von koordiniertem Wasser aus den Sulfinato-S-Komplexen {RS(O)2}nM(OH2)n [n = 2, M = Pd (1a, b); n = 3, M = Rh (4a, b)] mit 2,2-Dimethoxypropan gelang erstmals die gezielte Darstellung der Sulfinato-O,S-Komplexe {R(O)OS}nM (2a, b; 5a, b). Die O,S-Verknüpfung ergibt sich eindeutig aus dem chemischen Verhalten und den IR-Spektren. Die für die Bildung von Sulfinato-O,S-Komplexen notwendigen Kriterien werden diskutiert.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19771100208
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  • 187
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    Natürlich vorkommende Terpen-Derivate, 78. Weitere Inhaltsstoffe aus südafrikanischen Senecio-Arten (1977)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 110 (1977), S. 474-486 
    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, 78 Further Constituents of South African Senecio SpeciesFrom representatives of the section Rigidi besides already known compounds four new benzofurans (3, 5, 6, and 10) as well as six new furanoeremophilanes (13, 15, 19-21, and 23) are isolated. From Senecio pterophorus a new type of a pyrrolizidine derivative (25) is isolated. Senecio cissampelinus contains similar compounds (34-37). The structures are elucidated by spectroscopic methods as well as by some chemical reactions. The chemotaxonomical aspects are discussed.
    Notes: Aus Vertretern der Sektion Rigidi werden neben bereits bekannten Verbindungen vier neue Benzofurane (3, 5, 6 und 10) sowie sechs neue Furanoeremophilane (13, 15, 19-21 und 23) isoliert. Aus Senecio pterophorus wird ein neuer Typ eines Pyrrolizidin-Derivats (25) isoliert. Ähnliche Verbindungen (34-37) enthält Senecio cissampelinus. Die Konstitutionen werden durch spektroskopische Methoden sowie durch einige chemische Reaktionen geklärt. Die chemotaxonomischen Aspekte werden diskutiert.
    Additional Material: 6 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19771100210
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  • 188
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    Umsetzungen mit Monohydrazonen von Dicarbonylverbindungen, IV. Neue Synthesen von Pyrrolen und Pyrrolinen (1977)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 110 (1977), S. 491-499 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reactions with Monohydrazones of Dicarbonyl Compounds, IV. New Syntheses of Pyrroles and PyrrolinesKetones and aldehydes with an active methylene group condense easily with monohydrazones of glyoxal (1 + 2 → 3). The hydrazonoethylidene derivatives thus obtained can be reduced to give pyrroles, pyrrolines, pyrrolidines, or N-aminopyrroles.
    Notes: Methylenaktive Ketone und Aldehyde lassen sich mit Monohydrazonen des Glyoxals zu Hydrazonoethyliden-Derivaten umsetzen (1 + 2 → 3). Durch Reduktion dieser Produkte sind Pyrrole, Pyrroline, Pyrrolidine sowie N-Aminopyrrole darstellbar.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19771100212
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  • 189
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    1,3-Dipolare Cycloadditionen, 78. Additionen des C-(2,2′-Biphenylylen)-Nα-(4-chlorphenyl)-Nβ-cyanazomethinimins an Styrol, Alkene, Enolether und Enamine (1977)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 110 (1977), S. 522-539 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: 1,3-Dipolar Cycloadditions, 78. Additions of C-(2,2′-Biphenylylene)-Nα-(4-chlorophenyl)-Nβ-cyano-azomethine Imine to Styrene, Alkenes, Enol Ethers and EnaminesThe cycloaddition of the title compound 1 to styrene at 70°C produces 95% of a pyrazolidine; the hydrogenolytic degradation to 9-phenethylfluorene as well as the n. m. r. spectrum reveal the addition direction. The 1-cyanopyrazolidine derivative shows reactions typical for cyanamides. - The azomethine imine 1 likewise accepts many nonconjugated alkenes, cycloalkenes and derivatives of styrene in high yield. The cycloadducts of butyl vinyl ether, cis- and trans-propenyl propyl ether, β-methoxystyrene and vinyl acetate suffer with dilute acids elimination of alkoxide or acetate, respectively, and of the N-cyano group to yield 2-pyrazolines. The electrophilicity of the azomethine imine carbon center determines the addition direction; substituents on the ethylenic dipolarophile which stabilize positive charge in the transition state of cycloaddition show up in position 5 of the pyrazolidine.
    Notes: Die Cycloaddition der Titelverbindung 1 an Styrol bei 70°C ergibt 95% eines Pyrazolidins; die Additionsrichtung geht aus der Hydrogenolyse zu 9-Phenethylfluoren ebenso wie aus dem NMR-Spektrum hervor. Das 1-Cyanpyrazolidin zeigt für Cyanamide typische Reaktionen. - Das Azomethin-imin 1 addiert viele nichtkonjugierte Alkene, Cycloalkene und Derivate des Styrols in hoher Ausbeute, wobei spektroskopische Daten die Addukt-Strukturen sichern. Die Cycloaddukte des Butylvinylethers, cis- und trans-Propenylpropylethers, β-Methoxystyrols und Vinylacetats erleiden schon mit verdünnter Säure eine Eliminierung des Alkoxyls bzw. Acetats und des N-Cyans unter Bildung von 2-Pyrazolinen. Die Additionsrichtung des 1,3-Dipols wird von der Elektrophilie des Azomethin-imin-Kohlenstoffs bestimmt; Substituenten am ethylenischen Dipolarophil, die positive Ladung im Übergangszustand der Cycloaddition zu stabilisieren vermögen, erscheinen in 5-Stellung des Pyrazolidins.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19771100215
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  • 190
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    Reaktionen des 2,2,2-Trifluor-4,4,5,5-tetrakis(trifluormethyl)-1,3,2λ5-dioxaphospholans (1977)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 110 (1977), S. 611-618 
    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 2,2,2-Trifluor-4,4,5,5-tetrakis(trifluormethyl)-1,3,2λ5-dioxaphospholanePF5 and PhPF4 react with 2-[bis(trimethylsilyl)amino]-2,2-difluoro-4,4,5,5-tetrakis (trifluoromethyl)-1,3,2λ5-dioxaphospholane (1b) to yield the trifluorophosphorane 2 or 3, respectively. 3 is the first known example of a stable fluorophosphazophosphorane. 2 reacts with methoxytrimethylsilane to give the thermally stable difluoromethoxyphosphorane4; with hexamethyldisiloxane 5 is obtained. PF5 easily converts 5 into 2. Diphenyl(trimethylsilyl)phosphine reduces 2 to the cyclic fluorophosphite 6, which displaces the coordinated cycloolefin in (C7H8)Mo(CO)4 (C7H8 = norbornadiene) with formation of the cis-complex 7. The spectroscopic data are discussed.
    Notes: Die Reaktion von PF5 bzw. PhPF4 mit 2-[Bis(trimethylsilyl)amino]-2,2-difluor-4,4,5,5-tetrakis-(trifluormethyl)-1,3,2λ5-dioxaphospholan (1b) ergibt das Trifluorphosphoran 2 bzw. 3, das erste stabile Fluorphosphazophosphoran. 2 setzt sich mit Methoxytrimethylsilan zu dem thermisch beständigen Difluormethoxyphosphoran 4 um, mit Hexamethyldisiloxan entsteht 5, das mit PF5 leicht in 2 umgewandelt werden kann. Diphenyl(trimethylsilyl)phosphin reduziert 2 zu dem cyclischen Fluorphosphit 6, das in (C7H8)Mo(CO)4 (C7H8 = Norbornadien) das Cycloolefin unter Bildung des cis-Komplexes 7 substituiert. Die spektroskopischen Daten werden diskutiert.
    Additional Material: 2 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19771100222
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  • 191
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    1,3-Anionische Cycloadditionen, XIII. endo-exo-Isomere Cycloaddukte aus trans,trans-1,3-Diphenyl-2-azaallyllithium und Acenaphthylen (1977)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 110 (1977), S. 638-644 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: 1,3-Anionic Cycloadditions, XIII. endo-exo-Isomeric Cycloadducts of trans,trans-1,3-Diphenyl-2-azaallyllithium and Acenaphthylenetrans,trans-1,3-Diphenyl-2-azaallyllithium adds at O or -70°C to acenaphthylene with retention of configuration to give a mixture of N-lithio-syn- and N-lithio-anti-7,9-diphenyl-7,8,9,9a-tetrahydro-6bH-acenaphtho[1,2-c]pyrrole (3a, 4a, R = Li) (ca. 1:1). The syn-isomer (endo-cycloadduct) rearranges to the anti-isomer (exo-cycloadduct) at +35°C.
    Notes: trans,trans-1,3-Diphenyl-2-azaallyllithium (1) cycloaddiert sich bei O oder -70°C unter Retention an Acenaphthylen zu einem Gemisch von N-Lithio-syn- und N-Lithio-anti-7,9-diphenyl-7,8,9,9a-tetrahydro-6bH-acenaphtho[1,2-c]pyrrol (3a, 4a, R = Li) (ca. 1:1). Das syn-Isomere (endo-Cycloaddukt) lagert sich bei +35°C in das anti-Isomere (exo-Cycloaddukt) um.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19771100225
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  • 192
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    Einfache Phosphor- und Arsen-Ylide mit Methylgermanium-, -zinn- und -blei-Substituenten (1977)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 110 (1977), S. 677-682 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Some Simple Phosphorus and Arsenic Ylides with Methylgermanium, -tin, and -lead SubstituentsThe syntheses of the ylides (CH3)3P = C[Pb(CH3)3]2, (CH3)3P = C[Ge(CH3)3]2, and (CH3)2-[(CH3)3GeCH2]P = C[Ge(CH3)3]2 are reported. The relative substituent effect of all IVb elements on the carbanionic function of ylides is discussed in the light of the 13C and 31P n. m. r. spectra of these compounds and their Si and Sn analogues.
    Notes: Die Darstellung der Ylide (CH3)3P = C[Pb(CH3)3]2, (CH3)3P = C[Ge(CH3)3]2 und (CH3)2-[(CH3)3GeCH2]P = C[Ge(CH3)3]2 wird beschrieben. Der relative Substituenteneffekt aller IVb-Elemente auf die Carbanion-Funktion von Yliden wird an Hand der 13C- und 31P-NMR-Spektren dieser Verbindungen und ihrer Si- und Sn-Analoga diskutiert.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19771100230
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  • 193
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    Über Metallalkyl- und -aryl-Verbindungen, XIX. Darstellung und Kristallstruktur von Methylrubidium und Methylcaesium (1977)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 110 (1977), S. 717-720 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Metal Alkyl and Aryl Compounds, XIX. Preparation and Crystal Structure of Methylrubidium and MethylcaesiumCH3Rb and CH3Cs are prepared from CH3Li and rubidium tert-butoxide or caesium 2-methyl-2-pentanolate, respectively. As shown by X-ray diffraction of the crystal powders the compounds possess a hexagonal structure of the NiAs type with isolated methyl anions and alkali cations like CH3K investigated earlier.
    Notes: CH3Rb und CH3Cs werden durch doppelte Umsetzung von CH3Li mit Rubidium-tert-butylat bzw. Caesium-2-methyl-2-pentanolat dargestellt. Nach röntgenographischen Untersuchungen der Kristallpulver besitzen die Verbindungen wie das bereits früher untersuchte CH3K eine hexagonale Struktur vom NiAs-Typ mit isolierten Methyl-Anionen und Alkali-Kationen.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19771100234
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  • 194
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    Massenspektrometrische Untersuchungen an Dicarbonyl(cyclopentadienyl)(thioamidato)-Komplexen von Molybdän und Wolfram (1977)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 110 (1977), S. 730-736 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Mass Spectrometrical Investigations of Dicarbonyl(cyclopentadienyl)(thioamidato) Complexes of Molybdenum and TungstenThe mass spectra of several dicarbonyl(cyclopentadienyl)(thioamidato) complexes of Mo and W and of the corresponding free thioamides are reported and the fragmentation processes are discussed. The fragmentation modes of the ionized complexes reveal structural rearrangements of the organic ligands, which cannot be observed in the spectra of the free thioamides.
    Notes: Die Massenspektren einiger Dicarbonyl(cyclopentadienyl)(thioamidato)-Komplexe von Mo und W und die der zugehörigen freien Thioamide werden angegeben und die Fragmentierungsprozesse diskutiert. Der organische Ligand unterliegt im ionisierten Komplex tiefgreifenden strukturellen Umlagerungen, für die sich in den Spektren der freien Thioamide keine Parallele finden läßt.
    Additional Material: 4 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19771100236
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  • 195
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    Intramolekulare Wechselwirkungen zwischen Dreifachbindungen, XVI. Kristall- und Molekularstruktur von 5,6,12,13-Tetradehydro-8,9,10,11-tetrahydro-7H-dibenzo[a,c]cyclotridecen (1977)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 110 (1977), S. 744-748 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Intramolecular Interactions of Triple Bonds, XVI. The Crystal and Molecular Structure of 5,6,12,13-Tetradehydro-8,9,10,11-tetrahydro-7H-dibenzo-[a,c]cyclotrideceneThe crystal structure of the title compound was solved by direct methods and has been refined to R = 0.056. The triple bonds are crossed by an angle of 64.0°. Their centres have a distance of 3.174 Å. Because of transannular repulsion within the thirteen-membered ring system the acetylene group deviates by 4.1° and 4.6° respectively in a cisoid manner from a linear arrangement. The other angles are enlarged. In the present conformation the length of the [CH2]5-bridge corresponds the length of the CH2—S—S—CH2-group. The chiral molecule lies on a crystallographic twofold axis.
    Notes: Die Kristallstruktur der Titelverbindung wurde mit direkten Methoden gelöst und bis zu einem R-Wert von 0.056 verfeinert. Die Dreifachbindungen sind unter einem Winkel von 64.0° gekreuzt angeordnet und zeigen einen Mittelpunktsabstand von 3.174 Å. Auf Grund der transannularen Abstoßung innerhalb des dreizehngliedrigen Ringsystems ist die Acetylengruppe um 4.1° bzw. 4.6° aus der linearen Anordnung cisoid deformiert. Die übrigen Winkel sind aufgeweitet. Die Länge der [CH2]5-Brücke entspricht in der vorliegenden Konformation der einer CH2—S—S—CH2-Gruppe. Das chirale Molekül liegt auf einer zweizähligen kristallographischen Achse.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19771100238
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  • 196
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    Zur Frage der inneren Hexakoordination bei Pentaarylphosphoranen; Phosphoran-Umlagerungen auf dem Niveau der Koordinationszahl 5 (1977)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 110 (1977), S. 693-702 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The Question of Inner Hexacoordination with Pentaarylphosphoranes; Phosphorane Rearrangements at the Level of Coordination Number 5The spirocyclic pentaarylphosphoranes 13 and 18b containing hydroxy groups in the direct neighbourhood of the molecule centre, isomerize more or less readily to the oxyphosphoranes 14 and 22, resp., with retention of coordination number 5. Inner onium-ate complexations could not be detected with the starting materials.
    Notes: Die spirocyclischen Pentaarylphosphorane 13 und 18b, die in unmittelbarer Nachbarschaft zum Molekülzentrum Hydroxylgruppen aufweisen, isomerisieren mehr oder weniger leicht unter Beibehaltung des Koordinationsniveaus 5 zu den Oxyphosphoranen 14 bzw. 22. Innere Onium-At-Komplexierungen konnten bei den Ausgangsverbindungen nicht nachgewiesen werden.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19771100232
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  • 197
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    Über Reaktionen des 1,3,5-Trifluor-1,3,5-trioxo-1λ6,3λ6,5λ6,2,4,6-trithiatriazins (Sulfanurfluorid) mit Aminen (1977)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 110 (1977), S. 683-692 
    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 1,3,5-Trifluoro-1,3,5-trioxo-1λ6,3λ6,5λ6,2,4,6-trithiatriazine (Sulfanuric Fluoride) with AminesWhereas the reaction of the trithiatriazine 1 with diethylamine yields only mono- and disubstituted derivatives (2b, 3), the reaction with dimethylamine results in the replacement of one, two, or three fluorine atoms (→ 2a, 3a, 4). On the other hand, only mono- or trisubstituted compounds (5a, b or 9a, b, resp.), are formed by the reactions of 1 with primary amines such as methylamine and ethylamine. Ammonia reacts with 1 to give 10·NH3. The free compound 10 is formed by treatment with HCl gas. 10 reacts with P(C6H5)4Cl to yield the ionic compound 11 and with benzaldehyde to form the Schiff base 12. With secondary diamines 1 preferentially undergoes intermolecular linkage with formation of 13, but a bicyclic compound 14 could also be prepared in low yield. 1 reacts with silylamines such as RN(SiMe3)2 (R = CH3, C2H5) only after addition of RNH(SiMe3) (→ 15a, b). Sn—N cleavage reactions with 1 occur more readily. Only monosubstituted products (e. g. 16) are formed. Reaction of 1 with phenylhydrazine results in reduction of a sulfur atom and formation of the anion 17. A substituted anion (18) was also prepared from 2a by this method. The reaction behavior of 1 is discussed in detail.
    Notes: Während das Trithiatriazin 1 mit Diethylamin nur zu Mono- und Disubstitutionsderivaten (2b, 3b) reagiert, kann Dimethylamin ein, zwei oder auch drei Fluoratome austauschen (→2a, 3a, 4). Die Reaktion von 1 mit primären Aminen wie Methylamin und Ethylamin liefert hingegen nur Mono- und Trisubstitutionsprodukte (5a, b bzw. 9a, b). Ammoniak reagiert mit 1 zu 10·NH3, die freie Verbindung 10 entsteht nach Behandeln mit HCl-Gas. Mit P(C6H5)4Cl gibt 10 die ionische Verbindung 11, mit Benzaldehyd die Schiffsche Base 12. Mit sekundären Diaminen setzt sich 1 bevorzugt unter intermolekularer Verknüpfung (13) um, aber auch eine bicyclische Verbindung 14 ist in geringer Ausbeute darzustellen. Mit Silylaminen wie RN(SiMe3)2 (R = CH3, C2H5) reagiert 1 erst nach Zusatz von RNHSiMe3 (→ 15a, b). Sn-N-Spaltungsreaktionen mit 1 verlaufen erheblich leichter, wobei ausschließlich Monosubstitutionsprodukte (z. B. 16) gebildet werden. 1 gibt mit Phenylhydrazin unter Reduktion eines Schwefelatoms das Anion 17. Auch ein substituiertes Anion (18) konnte auf diesem Wege aus 2a dargestellt werden. Das Reaktionsverhalten von 1 wird ausführlich diskutiert.
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    URL: http://dx.doi.org/10.1002/cber.19771100231
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    Synthese der 8-, 4′- und 7-Monomethylether von Gossypetin (3,3′,4′,5,7,8-Hexahydroxyflavon) und Konstitutionsbeweis für Ranupenin aus Ranunculus repens L. (1977)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 110 (1977), S. 737-743 
    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 the 8-, 4′-, and 7-Monomethyl Ethers of Gossypetin (3,3′,4′,5,7,8-Hexahydroxyflavone) and Structure of Ranupenin from Ranunculus repens L.By synthesis of 8-, 4′- and 7-O-monomethylgossypetin via a modified Allan-Robinson condensation as well as directly from gossypetin (3,3′,4′,5,7,8-hexahydroxyflavone), it is shown that ranupenin from Ranunculus repens L., which occurs in the plant as an O-monogalactoside, has the structure not of 8-O-monomethyl- but of 7-O-monomethylgossypetin.
    Notes: Durch die Synthese von 8-, 4′- und 7-O-Monomethylgossypetin über eine modifizierte Allan-Robinson-Kondensation bzw. direkt aus Gossypetin (3,3′,4′,5,7,8-Hexahydroxyflavon) konnte geklärt werden, daß dem als O-Monogalactosid natürlich vorliegenden Ranupenin aus Ranunculus repens L. nicht die Konstitution eines Gossypetin-8-, sondern -7-methylethers zukommt.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19771100237
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  • 199
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    Molekularmechanische Berechnungen zur Stabilität von Brückenkopfolefinen (1977)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 110 (1977), S. 773-777 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Molecular Mechanics Calculations on the Stability of Bridgehead OlefinsEmpirical force field calculations were used to determine the limits of application of the rules proposed by Fawcett Wiseman and Köbrich for the stability of bridgehead olefins (Bredt compounds). The stability is ruled by the size of the trans-cycloolefin unit, whereas the sum of the number of atoms in the three bridges is of minor importance. With a given skeleton the double bond was found less favourable in the largest bridge than in the second largest in most cases studied.
    Notes: Mittels empirischer Kraftfeldrechnungen wird der Gültigkeitsbereich der Regeln von Fawcett, Wiseman und Köbrich zur Vorhersage der Stabilität von Brückenkopfolefinen (Bredt-Verbindungen) untersucht. Die Größe der trans-Cycloolefineinheit ist für die Stabilität ausschlaggebend, die Summe der Ringgliederzahl in den drei Brücken ist von untergeordneter Bedeutung. Bei gegebenem Gerüst ist in der Mehrzahl der untersuchten Moleküle die Doppelbindung in der größten Brücke weniger günstig als in der zweitgrößten.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19771100241
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  • 200
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    Derivate des Borabenzols, IX. Paramagnetische Chrom-Komplexe des 1-Methyl- und 1-Phenylborinat-Ions (1977)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 110 (1977), S. 816-819 
    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, IX. Paramagnetic Chromium Complexes of 1-Methylborinate and 1-Phenylborinate IonsPotassium borinates, K[C5H5B-R] (R = CH3, C6H5), react with CrCl3 or CrCl2·THF to give paramagnetic bis(borinato)chromium complexes, Cr(C5H5B-R)2 (R = CH3, C6H5). For these a sandwich structure with a 16-electron valence shell is proposed.
    Notes: Durch Umsetzung von Kaliumborinaten, K[C5H5B-R] (R = CH3, C6H5), mit CrCl3 oder CrCl2·THF werden paramagnetische Bis(borinato)chrom-Komplexe, Cr(C5H5B-R)2 (R = CH3, C6H5), erhalten. Für diese wird eine Sandwich-Struktur mit einer 16-Elektronen-Valenzschale vorgeschlagen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19771100303
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