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  • 1980-1984  (3,828)
  • 1965-1969
  • 1983  (3,828)
  • Polymer and Materials Science  (3,022)
  • Inorganic Chemistry  (702)
  • Ultrastructure  (104)
  • Nuclear reactions
Source
Material
Years
  • 1980-1984  (3,828)
  • 1965-1969
Year
Keywords
  • 101
    Electronic Resource
    Electronic Resource
    1H-NMR studies on poly(oxyethylene)-bound oligopeptides (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 163-169 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Conformational studies on poly(oxyethylene)-bound homo-, oligo-, guest-host, and sequential peptides synthesized according to the liquid-phase method were carried out by means of 1H-nmr spectroscopy. The solubilizing effect of the C-terminal polymeric support allowed a thorough investigation of the secondary structure in solution.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360220126
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  • 102
    Electronic Resource
    Electronic Resource
    Vibrational analysis of conformation in peptides, polypeptides, and proteinsThis is paper number 16 in a series of which Ref. 20 is paper 15. (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 217-225 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A vibrational force field for the polypeptide chain has been developed for normal-mode analysis of such molecules. It can reproduce observed frequencies of known structures to within about 5 cm-1. We review the application of this technique to conformational problems in peptides (β-turns and their model compounds), polypeptides [the αII-helix and crystalline poly(glycine II)], and proteins (bacteriorhodopsin and glucagon).
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360220130
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  • 103
    Electronic Resource
    Electronic Resource
    1H-NMR studies on substance P hexapeptide analogs (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 247-253 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1H-nmr studies of [pGlu6]SP6-11, [gpGlu6,mPhe7]SP6-11, and [pGlu6,N-CH3Phe7]SP6-11 in DMSO-d6 reveal characteristic chemical shifts, 3JNH-αCH, temperature dependence, as well as deuterium exchange half-times. Marked similarities are revealed for the two first analogs, whereas the N-methylated analog is clearly different. Possible conformations are considered.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360220134
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  • 104
    Electronic Resource
    Electronic Resource
    Conformational flexibility in a small globular hormone: X-ray analysis of avian pancreatic polypeptide at 0.98-Å resolution (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 293-304 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 36-amino acid avian pancreatic polypeptide has been studied by x-ray analysis at 0.98-Å resolution and refined using a restrained least-squares technique to an agreement factor of 15.6%. The polypeptide, which has a compact globular structure with a hydrophobic core, comprises a polyproline-like helix (residues 2-8) and an α-helix (residues 14-32). The molecule forms symmetrical dimers linked through zinc atoms in the crystal lattice. The high-resolution analysis defines sequence-dependent distortions in the α-helical parameters due to hydrogen bonding of water molecules and side chains. The thermal parameters indicate an increased flexibility of the main chain at the turn between the helices and in the C-terminal residues. For the first time, six-parameter anisotropic thermal ellipsoids have been refined for each atom; these define the directions of the molecular motions in the polypeptide, indicating concerted vibrations. The physiological roles of conformation, flexibility, and dynamics of this polypeptide hormone are discussed.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360220138
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  • 105
    Electronic Resource
    Electronic Resource
    Solid-state geometry and conformation of linear, diastereoisomeric oligoprolinesAbbreviations, description of the atoms, and conventions for the conformation of the peptide chain follow the recommendations of the IUPAC-IUB Commission on Biochemical Nomenclature [(1972) Biochem. J. 126, 773-780]. Further abbreviations used are: Ac, acetyl; n-Prp, n-propionyl; Mmp, 1-(3-mercapto-2-methylpropionyl); Piv, pivaloyl; t-Boc, tert-butyloxycarbonyl; t-Aoc, tert-amyloxycarbonyl; Z, benzyloxycarbonyl; Hyp, 4-hydroxyproline; Aze, azetidine-4-carboxylic acid; Thz, thiazolidine-4-carboxylic acid; Δβ-Pro, 3,4-dehydroproline; Aib, α-aminoisobutyric acid; Pip, pipecolic acid; pGlu, pyroglutamic acid; OMe, methoxy; OBzl, benzyloxy. (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 305-317 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We have carried out a systematic analysis of the solid-state conformational preferences of a number of linear homo-oligoprolines (to the tetramer) by ir absorption and x-ray diffraction. The peptides present different chiral sequences (tacticities), various types (urethane and amide) of N-protecting groups, and free and blocked C-termini (which imply different capabilities of forming H-bonds). The following conclusions can be drawn: (i) values for the geometry of the prolyl residue and the peptide bond in the cis and in the trans conformations are proposed; (ii) in general the conformational angles ϕ and ψ in the linear homo-oligoprolines have values appropriate for the polyproline II structure (conformation F); (iii) the pyrrolidine ring shows various types of puckering with no apparent relation to the backbone conformation; (iv) Pro-Pro peptide bonds generally take the trans conformation, the few cases of cis conformation being formed by Pro residues of different chirality; (v) the single H-bond donor  -  OH, when present, is always bonded to H-acceptors, which can be either the urethane or the amide or the peptide carbonyl but never the carbonyl group of the  -  COOH moiety.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360220139
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  • 106
    Electronic Resource
    Electronic Resource
    Microheterogeneity of bovine myelin basic protein studied by nuclear magnetic resonance spectroscopy (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 377-380 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Myelin basic protein isolated from bovine white matter is known to consist of a mixture of three or more “charge isomers”, which can be separated by cation-exchange chromatography. We are using 360-MHz 1H-nmr spectroscopy to establish the chemical and structural differences among them. Preliminary studies by difference spectroscopy between two of the isomers suggest (a) all aromatic residues, and probably their nearest-neighbors, are unchanged; (b) the less cationic isomer lacks one (or two) of its C-terminal Arg residues; and (c) a significant fraction of the two Met residues in the less cationic isomer is present as methionine sulfoxide.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360220148
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  • 107
    Electronic Resource
    Electronic Resource
    Spectroscopic studies of a hydrophobic peptide in membranelike environments (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 381-385 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A hydrophobic linear peptide has been synthesized and studied over a range of environments using several complementary spectroscopic approaches, including nmr, CD, and vibrational spectroscopies. The sequence of this model peptide, carbobenzoxy-L-Pro-D-Phe-D-Ala-L-Pro-NHCH3, was designed such that a small number of “folded” conformations, stabilized by intramolecular hydrogen bonding, would be accessible to it. Additionally, the extremely hydrophobic character of the peptide favors its interactions with hydrophobic regions of a membrane. The conformational impact of the membrane environment on the peptide, and the effect of the peptide on lipid organization have been explored both in micellar media and in vesicles. To facilitate nmr analysis, the peptide has been synthesized with one of the prolines perdeuterated. Results of these studies reveal that the peptide experiences a microenvironment of moderate polarity in micellar media and causes changes in lipid structure in a vesicle that are indicative of a hydrophobic peptide-lipid interaction.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360220149
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  • 108
    Electronic Resource
    Electronic Resource
    How antigenic are antigenic peptides? (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 425-440 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Most of a protein surface is potentially antigenic, consisting of numerous overlapping domains each complementary to antibody-combining sites. These domains may include peptide sequences that are demonstrably antigenic but only when antibodies from the appropriate host individuals and species are used. Methods for locating antigenic peptide sequences are described in which hydrophilic polyamide supports are used for peptide synthesis, then solid-phase radioimmunoassay with antisera and protein A. Most antigenic domains, however, comprise amino acid side chains contributed by two or more nearby polypeptide chains. Such domains can be identified by comparing the cross-reactivities of groups of very closely related proteins towards monoclonal antibodies raised to one of them. Such studies, using myoglobins, have identified a number of residues not previously shown to be antigenic and have provided a guide for the choice of synthetic peptides which are likely to carry several immunodominant side chains. One such peptide corresponding to residues (72-89) of beef myoglobin has been shown, using CD and antibodies to the parent protein, to have interesting conformational and antigenic properties. The peptide (25-55) is also antigenic.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360220156
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  • 109
    Electronic Resource
    Electronic Resource
    Some novel approaches to the design and synthesis of peptide-catecholamine conjugates (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 531-545 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of novel, functionalized catecholamines (congeners) has been synthesized in which, formalistically, the N-isopropyl group of isoproterenol has been extended by a linear alkyl chain of varying length, terminated by a carboxyl group. Model amide derivatives have also been prepared in order to optimize the biological activity of these derivatives and also to aid in the design of appropriate peptides for the synthesis of conjugates. As a result of these studies, a series of amino acid and monodisperse peptide carriers, containing p-aminophenylalanine as the point of attachment for the drug, was prepared, together with the corresponding conjugates. In vitro and in vivo evaluation of the congeners, model amides, and conjugates has demonstrated that the biological activity of these derivatives is extremely sensitive to structural modifications at a point far-removed from the pharmacophore, in both the congener amide and conjugate series. A number of the model amides and conjugates have proven to be highly active when tested in both in vitro and in vivo test systems. The implications of these results in terms of a novel structure-activity approach to drug design are discussed.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360220166
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  • 110
    Electronic Resource
    Electronic Resource
    Specific and nonspecific macromolecule-drug conjugates for the improvement of cancer chemotherapy (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 557-567 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Antineoplastic drugs such as daunomycin, adriamycin, methotrexate, 5-fluorouridine, cytosine arabinoside, and platinate were bound to antibodies directly or via a polymeric bridge. The drug antibody conjugates retained most of their drug and antibody activities when tested in vitro. Daunomycin-antibody conjugates were shown to penetrate tumor cells in the conjugated form. In animals, daunomycin-antibody conjugates were at least as effective chemotherapeutically as the corresponding free drugs and considerably less toxic. In some tumor systems, the daunomycin-antibody conjugates represented an improvement over the free drug. This improvement was restricted in some tumors to a particular injection route of the tumor and the treatment.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360220168
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  • 111
    Electronic Resource
    Electronic Resource
    Synthesis and spectroscopic characterization of insulin derivatives containing one or two poly(ethylene oxide) chains at specific positions (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 569-573 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We describe a synthetic method aimed at specifically coupling poly(ethylene oxide) (PEO) to proteins without altering their spectroscopic properties. To do so, we have first modified the alcohol end group of PEO to an acid end group (PEO-COOH). Coupling of PEO-COOH to Gly A1 methylsulfonylethyloxycarbonyl (Msc) protected insulin yielded NαB1,N∊B29-(PEO)2-insulin. Conversely, coupling of PEO-COOH to insulin whose Gly A1 and Lys B29 amino groups were protected with Msc yielded NαB1-PEO-insulin. The products were obtained in a spectroscopically pure form and characterized by uv and CD spectroscopy. Conformational and biological studies are in progress.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360220169
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  • 112
    Electronic Resource
    Electronic Resource
    Poly(2-aminodeoxyadenylic acid): Circular dichroism and thermal stability of its complexes and their relevance to phage DNA in which A is replaced by 2NH2A (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 597-600 
    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.360220204
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  • 113
    Electronic Resource
    Electronic Resource
    Crystal structure and conformation of a cyclic tetrapeptide cyclo(L-Pro-Sar)2 containing all-cis peptide units (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 633-641 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The crystal structure and conformation of the synthetic cyclic tetrapeptide, cyclo(L-Pro-Sar)2, was determined by x-ray analysis. The peptide crystallizes in the orthorhombic space group P212121 with cell parameters a = 9.277(1), b = 12.884(1), and c = 15.581(2) Å. The crystal structure was solved by the symbolic addition procedure for direct phase determination and least-squares refinement using 1796 reflections, which led to the final R value of 0.043. This structure provides the first example observed in a crystal of a cyclic tetrapeptide in which all four peptide units have been found in the cis conformation with ω angles deviating slightly by 2°-10° from the ideal value of 0°. It was also found that the two Pro Cα-CO single bonds assumed a trans′ (ψ = 159.6° and 158.4°) conformation. Adjoining average planes of the peptide groups fall at nearly right angles to each other. The pyrrolidine ring conformations of the two prolyl residues are in the envelope form, with Cγ carbon out of the least-squares planes for the remaining four atoms.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360220208
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  • 114
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    An analysis of the sequence dependence of the structure and energy of A- and B-DNA models using molecular mechannics (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 969-1002 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Molecular-mechanics calculations have been carried out on the base-paired hexanucleoside pentaphosphates d(TATATA)2, d(ATATAT)2, d(A6)·d(T6), d(CGCGCG)2, d(GCGCGC)2, and d(C6)·d(G6) in both A- and B-DNA geometries. The calculated relative energies of these polymers are consistent with the relative stabilities of the polymers found experimentally. In particular, the results of our calculations support the observation that the homopolymer d(A)n·d(T)n is more stable in a B-DNA conformation, while the homopolymer d(G)n·d(C)n is more stable in an A-DNA conformation. The molecular interactions responsible for these differential stabilities include both inter- and intrastrand base stacking, as well as base-phosphate interactions. While definitive experiments on the heteropolymer stabilities have not yet been carried out, the results of our calculations also suggest a greater stability of the purine-3′,5′-pyrimidine sequence over the pyrimidine-3′,5′-purine sequence in both the A- and B-conformations. The reason for this greater stability lies in the importance of the inherent directionality (5′ → 3′ vs 3′ → 5′) of phosphate-base and base-base interactions. The largest conformation change observed on energy refinement is sugar repuckering, which occurs mainly on pyrimidine-attched sugars and only in the B-DNA geometry. We suggest a molecular mechanism, specifically, differential base-sugar steric interactions involving neighboring sugars, to explain why this repuckering occurs more with d(A6)·d(T6) than with other isomers.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360220316
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  • 115
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    Electronic Resource
    Salt- and sequence-dependence of the secondary structure of DNA in Solution by 31P-nmr spectroscopy (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 879-893 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We examined three sonicated, specific-seqiemce polydeoxynucleotides in solution over a wide range of concentrations of several salts by 13P-nmr spectroscopy, and we found that the alternating copolymer poly(dAdT)·poly(dAdT) exhibits a dinucleotide repeat unit in all five salts and at all concentrations studied, as indicated by the presence of a doubled in its 31P-nmr spectra. The two components of the doublet show selective shift effects. The upfield component is assigned to dApdT in the gauche--gauche- conformation and shifts upfield in all four monovalent salts used, relative to a single-stranded oligonucleotide control. The downfield component is assigned to dTpdA in the trans-gauche- conformation and shifts downfield with increasing CsF concentration but remains essentially constant in LiCl, NaCl, and CsCl. These changes indicate a fast noncooperative transition for poly(dAdT)·poly-(dAdT) from a presumed right-handed dinucleotide-repeat B-form to another conformation with a dinucleotide-repeat structure, via a continuum of structures that may differ in the extent of the winding of the double helix. Ethanol causes the upfield component to collapse into the other component, indicating conversion to a structure with a mononucleotide repeat unit and a trans-gauche- conformation. Up to 1M Mg2+ appears to have no significant effect on the phosphodiester conformations of poly(dAdT)·poly(dAdT). By contrast, poly-(dGdC)·poly(dGdC) gives a slow cooperative transition from what is considered to be a right-handed regular B-form to a left-handed Z-form on increasing MgCl2 and NaCl concentrations, although we observed no changes in chemical shifts below the transition points. The homopolymer poly(dA)·poly(dT) exhibits no unusual shift effects or transitions upon the addition of salts when compared to the oligonucleotide control and is considered to be a regular B-form with a gauche--gauche- phosphodiester backbone conformation. These differences emphasize the distinct secondary structures of DNAs of different sequences and their selective responses to changes in solution conditions.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360220310
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  • 116
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    1H-nmr studies on the dinucleoside monophosphates containing 2′-halogeno-2′-deoxypurinenucleosides: Effects of 2′-substitutes on conformation (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 1189-1202 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Seven dinucleoside monophosphates containing 2′-halogeno-2′-deoxypurine nucleoside residue, dAfl-U, dAcl-U, dAbr-U, dAio-U, dGfl-U, and dIfl-C, were chemically synthesized and investigated by 1H-nmr spectroscopy at 300 MHz. The sugar and backbone conformations of these compounds were analyzed by the spectral pattern of furanose proton resonances; and the extents of base-base interaction were estimated from chemical shifts and their temperature-dependent changes of base-proton resonances. It is found that the population of C3′-endo conformer and the extent of base-base interaction decrease as the electronegativity of 2′-substituent decreases in dAx-U (x = fl, cl, br, and io) series. The C3′-endo (3E) population and the base-base interaction in Nfl-U (N = A,G)-type dimers as well as dIfl-C are relatively higher than the corresponding natural ribo-dimers but can be recognized as grossly similar to the conformation of regular RNA dimers.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/bip.360220412
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  • 117
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    Masthead (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983) 
    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.360220501
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  • 118
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    Raman spectra and normal vibrations of dipeptides. I. Glycylglycine (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 1267-1283 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We studied the Raman spectra of the zwitterionic glycylglycine crystal (GG) and its N-deuterated analog. A normal coordinate analysis on its α-crystalline form was performed and the effects of intra-and intermolecular couplings are discussed. A modified Urey-Bradley potential was used as a model of the intramolecular force field. Factor group splittings are described by the use of intermolecular potentials consisting of nonbonded atom-atom interactions and dipole-dipole interactions. Effects of hydrogen bonds on the vibrational frequencies of amino and carboxylate groups are also analyzed.
    Additional Material: 9 Ill.
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    URL: http://dx.doi.org/10.1002/bip.360220503
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  • 119
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    Peptaibol antibiotics: Conformational preferences of synthetic emerimicin fragmentsThis is part 90 of the Linear Oligopeptides series. For part 89, see Toniolo, C., Bonora, G. M., Anzinger, H. & Mutter, M. (1982) Macromolecules (in press). (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 1335-1356 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The ir absorption and CD conformational analyses of solutions of the protected 2-9 fragment of the peptaibol antibiotics emerimicins III and IV \documentclass{article}\pagestyle{empty}\begin{document}$ \rlap{--} (Aib_3 \rlap{--} )L - Val - Gly - L - Leu\rlap{--} (Aib_2 \rlap{--} ) $\end{document} and related short sequences are consistent with the presence of a right-handed α-helix for the octapeptide, while the tri-, tetra-, and pentapeptides adopt a 310-helix, either right- or left-handed, depending on the amino acid sequences. The structural preferences of solid-state \documentclass{article}\pagestyle{empty}\begin{document}$ Z\rlap{--} (Aib_3 \rlap{--} )L - Val - OMe $\end{document} and \documentclass{article}\pagestyle{empty}\begin{document}$ Z\rlap{--} (Aib_3 \rlap{--} )L - Val - Gly - OMe $\end{document} have been determined by x-ray diffraction. In accord with the solution data, incipient 310-helices, formed by two and three β-turns, have been found for the tetra- and pentapeptides, respectively. The tetrapeptide helix has the left-handed screw sense, while that of the pentapetide is right-handed, thus confirming the conclusions of the CD analysis of the solution.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/bip.360220507
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  • 120
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    Mobility of oligopeptides on normal-phase silica: Effect of positional isomerism (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 1401-1407 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Isomeric oligopeptides composed of five methionyl residues and one glycyl residue or of five γ-methyl-L-glutamyl residues and one glycyl residue all exhibit marked differences in retention on normal-phase silica. When the glycyl residue is at internal positions of hexa or heptapeptides, the peptide elutes most rapidly form the μPorasil column. Comparison of the effect of positional isomerism on retention in short oligopeptides with the effect on retention of hexamers and heptamers suggests that a change in peptide conformation may be responsible for the change in oligopeptide mobility.
    Additional Material: 3 Ill.
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    Vacuum-ultraviolet circular dichroism of sodium hyaluronate oligosaccharides and polymer segments (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 1319-1334 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The CD spectrum of an enzymatically derived sodium hyaluronate (NaHA) segment preparation with chain length 18 ± 3 disaccharide units [NaHAseg, ( NaGlcUA GlcNAc)15-20°. NaGlcUA, sodium D-glucuronate; GlcNAc, 2-acetamido-2-deoxy-D-glucose] in H2O was recorded to 180 nm using a computer-controlled vacuum-uv CD instrument. Near 190 nm the spectrum is of low intensity, similar to the sum of the free monosaccharide contributios, attributed to the π-π* transitions of the acetamido and carboxylate substituents. In contrast, much smaller oligosaccharides, also derived from high-molecular-weight NaHA by enzymatic digestions, show CD spectra in H2O with prominent bands centered near 190 nm. The oligosaccharide spectra can be matched as linear combinations of interior sugar residue (= NaHAseg) and end sugar residue CD contributions. End residues from oligosaccharides of the type (NaGlcUA-GlcNAc)n show a negative CD band near 190 nm. End residues from oligosaccharides of the reverse sequence (GlcNAc-NaGlcUA)n show a positive CD band near 190 nm. Averaging of the two end-residue spectral contributions yields an approximate match for the spectrum of NAHAseg below 200 nm. It is proposed that the low intensity CD of NaHA in the π-π* region is the result of large-magnitude, oppositely signed contributions, which can be visulized by studying oligosaccharides.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/bip.360220506
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    Structure of a cellulose II-hydrazine complex (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 1383-1399 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The structure of a crystalline cellulose II-hydrazine complex has been determined by x-ray diffraction methods as part of an investigation of cellulose-solvent interaction. The complex studied was that formed when Fortisan fibers were swollen in hydrazine and then vacuumdried. The unit cell is monoclinic with dimensions a = 9.37 Å, b = 19.88 Å, c = 10.39 Å, and γ = 120.0° and contains disaccharide segments of four chains, with one hydrazine per glucose residue. In view of the limited x-ray intensity data, the structure has been determined based on an approximate unit cell containing two chain segments, with a = 4.69 Å, using the linked-atom least-squares refinement procedures. The refined model contains antiparallel cellulose chains that are linked by both intermolecular hydrogen bonds and hydrogen-bonded hydrazine molecules. The parallel chains in the 020 planes are packed in register, leading to stacks of chains analogous to those in chitin. All the hydroxyl groups are satisfactorily hydrogen-bonded, and each hydrazine forms four donor and two acceptor hydrogen bonds, including an N—H…N bond between hydrazines. From this work it can be seen that the interaction of cellulose II with hydrazine involves scission of the intermolecular hydrogen bonds followed by disruption of the stacks of quarter-staggered chains. The latter effect is probably necessary for hydrazine to act as a cellulose solvent.
    Additional Material: 6 Ill.
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    Vacuum ultraviolet circular dichroism of poly(dI-dC)·poly(dI-dC): No evidence for a left-handed double helix (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 1445-1448 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/bip.360220602
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    Conformational analysis of acetyl-L-phenylalanine p-acetyl and p-valeryl anilides (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 1489-1498 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Empirical force-field calculations and ir and 1H-nmr spectra indicate that five-membered (C5) and seven-membered (C7eq) hydrogen-bonded rings are the preferred conformations of acetyl-L-Phe p-acetyl and p-valeryl anilides in nonpolar media. The C5/C7eq ratio was found to be dependent on the dryness of the solute and the solvent. This fact and the results from conformational-energy calculations suggest that a molecule of water participates in the stabilization of the C7eq conformation.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/bip.360220605
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    X-ray diffraction study of the interaction of the amino terminal half-molecule of histone H4 with duplex DNA (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 333-339 
    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 the amino terminal half-molecule of histone H4 with duplex DNA has been studied by fiber x-ray diffraction. Changes induced in the diffraction pattern of B-DNA by the presence of the bound peptide have been Fourier-analyzed and the results presented in terms of a deweighted radial projection of the electron density. We conclude that the peptide binds on the major groove side of the sugar-phosphate chain.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/bip.360220143
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  • 126
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    Neurophysin-neuropeptide hormone complexes: Biosynthetic origin and noncovalent interactions (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 355-362 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Recent studies of the neurophysins and associated neuropeptide hormones have addressed both the biosynthetic pathways by which these noncovalent protein-peptide complexes are derived in neurosecretory neurons and the nature of the noncovalent interactions likely to occur during transport and storage in neurosecretory granules within the neurons. In vitro translation of hypothalamic mRNA and sequencing of cDNA obtained from this mRNA have yielded chemical evidence that each complex of hormone and major neurophysin is made through a common precursor molecule. The mature complexes obtained upon proteolytic processing of precursors exhibit interdependent hormone binding and self-association interactions. Photoaffinity labeling and quantitative affinity chromatography have helped detect and define the binding surfaces involved. Further study of the structural nature of these surfaces is being carried out using large neurophysin fragments obtained by limited tryptic proteolysis.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/bip.360220146
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    Gramicidin a adopts distinctly different conformations in membranes and in organic solvents (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 397-402 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Gramicidin A exists in distinctly different conformations in phospholipid vesicles and in organic solvents. These different folding motifs are also reflected in crystals of gramicidin formed in the presence and absence of lipid molecules.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/bip.360220152
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    Design, synthesis, and conformation of ion carriers (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 409-414 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Macrocyclic molecules can serve as ion carriers when their polar groups form an inner cage to capture ions while their hydrophobic groups form an outer layer to dissolve the molecule in lipid membranes. A “template method” has been developed for high-yield synthesis of a whole variety of macrocyclic esters, amides, and other families which may show ionophoric properties. In order to select the more promising compounds for synthesis, energetic and conformational characteristics of such molecules have been calculated from empirical energy functions. Calculations are examined using known structures and are employed to predict the properties of molecules not yet synthesized.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/bip.360220154
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    The T-cell receptor as analyzed by functional T-cell lines specific to a synthetic polypeptide antigen (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 453-464 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: For a better understanding of the molecular nature of the antigen-specific T-cell recognition system, continuous T-cell lines specific to the synthetic polypeptide antigen poly(Tyr,Glu)-poly(DLAla)--poly(Lys) [(T,G)-A--L] were established from C3H.SW (high-responder) activated T-cells, cloned, and characterized. These lines and their derived clones are also constitutive secretors of antigen-specific T-cell replacing helper factors. The secreted T-cell helper factor was shown to possess MHC determinants as well as V-region determinants, or more specifically, idiotypic determinants that are cross-reactive with those expressed on (T,G)-A--L-specific antibodies of the same mouse strain. Using the fluorescence-activated cell sorter (FACS II) and individual C57BL/6 anti-idiotypic sera produced against (T,G)-A--L-specific antibodies of C3H.SW origin, we have demonstrated the expression of the cross-reactive idiotypic markers on the monoclonal helper T-cells. Attempts were made to purify the active fraction of the T-cell factors secreted by the (T,G)-A--L continuous helper lines. Gel analysis of the twice affinity-purified eluate of a (T,G)-A--L column revealed the existence of iodinated bands with molecular weight of 17,000 and 15,000, in addition to a diffuse band of high molecular weight. The specific helper activity of the factors was associated with a 65-75% ammonium sulfate precipitate. Gel electrophoresis of the latter fraction, as well as of an eluate of a (T,G)-A--L-Sepharose column indicated that a high-molecular-weight (〈 67,000) and a low-molecular-weight (15,000-17,000) fraction contained the biological activity of the factor. Similar results were obtained following chromatography of the factor on Sephadex G-100 columns. The two fractions were shown to be synthesized by the T-cell lines, as indicated by internal labeling experiments using 35S-methionine. Thus, it is suggested that a fraction of an apparent molecular weight of 15,000-17,000 preserves both the antigen specificity and the helper activity of the factor produced by the (T,G)-A--L-specific T-cell lines.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/bip.360220158
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    β-Galactosidase: Immune recognition of conformation and mechanism of antibody-induced catalytic activation (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 465-473 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Activation of mutant β-galactosidase by antibodies can be explained by a “selection” mechanism in which the antibody binds and stabilizes those mutants in a native-like conformation and by an “induction” mechanism where binding of the antibody itself induces a conformational change activating β-galactosidase. The “selection” hypothesis was tested by passing β-galactosidase through a column packed with monoclonal antibody-derivatized Sepharose. The antibody retains the active, in preference to the inactive, proteins. The “induction” mechanism was tested by mixing antibody-Sepharose with mutant β-galactosidase and measuring enzyme activity before mixing and that remaining in the supernatant. The activity of the antibody-Sepharose pellet exceeded the sum of the original activity plus supernatant activity. As a result of these experiments, both mechanisms are found to be operative.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/bip.360220159
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    Exploitation and exploration of ceruletide and eledoisin, two peptides of nonmammalian origin (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 507-515 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Eledoisin and ceruletide, two nonmammalian hormonelike peptides, have been explored for possible pharmaceutical application. At present, only a few of the potentialities of the two drugs have been exploited. Eledoisin is used in ophthalmology as a lachrymal secretagogue; ceruletide is applied in the radiological diagnosis of gallbladder, biliary system, and digestive tract disorders, in the study of exocrine pancreatic function, and in the treatment of postoperative paralytic ileus and intestinal hypotony and atony. Possible analgesic and antipsychotic applications of ceruletide are under study. Developments of synthetic and analytical methods for both peptides are briefly reviewed. Technical devices or alternative routes of administration are envisaged in order to enlarge both the present market and the field of application.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/bip.360220164
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    Proton NMR studies of partially modified retro-inverso peptides (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 1869-1883 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: High-resolution 1H-nmr analyses are presented for partially modified retro-inverso derivatives of peptides with emphasis on enkephalins. Studies in DMSO-d6 reveal the unique as well as common characteristics of the non-amino acid residues incorporated into these modified peptides. The complete assignment of 1,1-diaminoalkyl and malonyl, as well as of amino acid, residues provides the basis for the exploration of the conformational features induced in peptides by such topochemical modifications.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/bip.360220805
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  • 133
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    Fluorescence correlation spectroscopy and photobleaching recovery of multiple binding reactions. II. FPR and FCS measurements at low and high DNA concentrations (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 1949-1966 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The preceding paper develops the theory for the interpretation of fluorescence photobleaching recovery (FPR) measurements of multiple binding of a ligand to a multivalent substrate molecule. Based on a reasonable assumption about the mechanism of the photobleaching process, this analysis shows that the observed behavior of a multivalent system should be practically identical to that of a univalent binding system. This is in contrast to the expected and observed behavior of fluorescence correlation spectroscopy (FCS) measurments. Experimental FPR measurements of multivalent binding of ethidium bromide to DNA confirm these conclusions. The FCS and FPR measurements also reveal an apparently enhanced diffusion of ethidium at high DNA concentration. This enhancement might result from direct transfer of ethidium among DNA molecules.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/bip.360220809
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    Correlation of Tm, sequence, and ΔH of complementary RNA helices and comparison with DNA helices (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 2001-2016 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Tm values of 16 fully complementary RNA duplexes with repeating base sequence have been employed as the empirical basis for developing a reliable and practical method for computing apparent enthalpies (ΔHcalc) for their helix → coil transitions. The approach taken is the same as in the accompanying investigation of DNA duplexes, although some of the computational variables of the “best-fit” function are necessarily different due to the distinguishing structural properties of the RNA-type helix. An excellent linear correlation was thus obtained between experimental Tm and ΔHcalc values. An equally good fit was obtained between Tm and ΔHcalc for five unrelated (to the 16 RNAs) decaribonucleotide duplexes. The differences in computational variables between the best-fit methods for RNA and DNA duplexes are shown to be a reflection of differences in cation binding and the effective local dielectric. The greater Tm dependence on G·C content of RNA helices than of DNA helices is shown to be due to a greater latitude of stacking stabilities of complementary dinucleotide fragments containing A·T than A·U base pairs.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/bip.360220812
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    Possible observation of a defect resonance in DNA (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 2045-2060 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A sharp feature is observed at about 600 MHz in the inelastic scattered light spectrum of fibers of calf thymus DNA. It broadens so as to be no longer distinctly resolved when the ordering of a fiber is disrupted by convection caused by laser heating. To within experimental uncertainties the frequency of this feature is wavevector independent. A possible origin of the feature lies in a defect resonance such as that associated with the chain terminus.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/bip.360220905
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    Infrared spectroscopic study of C7 intramolecular hydrogen bonds in peptidesContribution No. 156 from the Solid State and Structural Chemistry Unit. (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 2091-2104 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The ir-spectra in the N—H stretching region of Piv-Pro-NHMe and Boc-Pro-NHMe have been studied in carbon tetrachloride and chloroform solutions over a wide range of concentrations. Based on the concentration dependence of the N—H stretching bands, it has been shown that the characteristic N—H stretching band due to the C7 intramolecular hydrogen bond is around 3335 cm-1. Intermolecular hydrogen bonding also occurs to a small extent in these peptides, giving rise to a slight concentration dependence of the N—H stretching bands. The band around 3335 cm-1 need not necessarily be due to C7 hydrogen bonds alone as proposed by Tsuboi et al. or to intermolecular hydrogen bonding alone as proposed by Maxfield et al.; this conclusion is supported by studies on Boc-Leu-NHMe, which undergoes only intermolecular hydrogen bonding. We have shown that Z-Aib-Aib-OMe and Z-Aib-Ala-OMe form C7 intramolecular hydrogen bonds in addition to C5 intramolecular hydrogen bonds. The present studies also show that all the peptides studied exist in more than one conformation in solution.
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    URL: http://dx.doi.org/10.1002/bip.360220908
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    Comparison of analytically and numerically derived hydrogen exchange-rate distribution functions (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 895-909 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Hydrogen exchange-rate probability density functions for lysozyme have been derived by numerical Laplace inversion with the computer program CONTIN. The resulting solution set includes a smooth bimodal solution in agreement with previous analytical results together with a smooth three-peak solution. Numerical analysis of lysozyme hydrogen-exchange data in glycerol/water cosolvent mixtures confirms the previous assignment of the slow-exchange peak to an exchange mechanism involving reversible unfolding. Physicochemical constrations that can reduce the size of the solution set are described. The results are compared with those obtained from previous analytical methods and the limitations of the discrete class and analytical appraches are discussed.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/bip.360220311
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    High-resolution nmr studies of A- and G-containing oligonucleotides (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 919-933 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We report the temperature dependence of the H2 and H8 purine ring proton resonances of oligoriboadenylates up to chain length 11, with or without a single guanosine residue at the 5′-end, second position, or 3′-end. The results suggest the following generalizations: (1) Stacking of the bases in a right-handed single-stranded helix is more extensive in the interior of the chain than at the chain ends. (2) The tendency of the terminal base to unstack is greater at the 5′-end than at the 3′-terminus. (3) G stacks more weakly than A, as evidenced by weak stacking of 3′-terminal G. Anomalies were also observed in the unstacking profile of G at the second position in the chain, indicating a conformational anomaly such as looping out of G, thereby allowing adjacent A's to stack together, or adoption by G of some other alternative structure. (4) The results imply that the environment at a given base is influenced by effects of longer range than nearest- or next-nearest-neighbor. Increasing ion condensation as chain length increases may be responsible for the slow approach of oligomer behavior to the properties of the high polymer.
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    URL: http://dx.doi.org/10.1002/bip.360220313
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    Masthead (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983) 
    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.360220401
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  • 140
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    Collapse of DNA caused by trivalent cations: pH and ionic specificity effects (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 1097-1106 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A comparison of the condensation of T4 phage DNA by spermidine and Co(NH3)63+ at pH values between 5.1 and 10.2 has been made using quasielastic light scattering to determine translational diffusion coefficients and Stokes radii. Co(NH3)63+ is more effective than spermidine in causing condensation at all pH, indicating that the differences observed in previous work were not due to pH effects, as might have been inferred from recent theories of intermolecular forces. The DNA particles collapsed with Co(NH3)63+ are smaller than those obtained with spermidine. The hydrodynamic radius of spermide-collapsed structures decreases slightly with increasing pH, while the size of the Co(NH3)63+collapsed structures is almost independent of pH. These results confirm that there are specific ion effects in DNA condensation by oligocations, in addition to the dominant general polyelectrolyte effects.
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    URL: http://dx.doi.org/10.1002/bip.360220407
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    Nuclear magnetic resonance study of ring conformations of cyclic tetradepsipeptide AM-toxins and related peptides (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 1167-1187 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cyclic tetradepsipeptides, AM-toxin I and II, are the host-specific phytotoxins of Alternaria mali. In order to elucidate conformation-toxicity relationships, we analyzed the 270-MHz proton nmr spectra of AM-toxins and hydrogenated analogs, (D-Ala2)AM-toxin I (toxic) and (L-Ala2)AM-toxin I (not toxic), in (C2H3)2SO. These cyclic tetradepsipeptides do not contain N-substituted amino acid residues, and all the peptide and ester groups have been found to be transoid. Two conformers with very unequal populations have been found for AM-toxin I and II; the Cβ=Cα—C=O conformations of the Dha2 residues are nonplanar S-trans in the major conformer and nonplanar S-cis in the minor conformer. Only one ring conformation has been found for each of (L-Ala2) and (D-Ala2)AM-toxin I. (L-Ala2)AM-toxin I takes a C4-type ring conformation; all the C=O groups and Cα-H bonds are oriented to the same side of the ring. (D-Ala2)AM-toxin I takes a new ring conformation; the side chain and C=O group of the L-Amp1 residue are oriented to the same side of the ring. This new conformation is also found for the major conformers of AM-toxin I and II and thus appears to be required for the toxicity. The ring conformations of Tyr(OCH3)1-bearing analog tetradepsipeptides have been found to be much the same as those of Amp1-bearing depsipeptides. Furthermore, on the basis of the two distinct conformations of (D-Ala2) and (L-Ala2)AM-toxin I, an empirical rule is proposed for the stable ring conformations of cyclic tetra-D,L-peptides, not containing N-substituted amino acid residues.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/bip.360220411
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    Temperature-jump kinetics of the dC-G-T-G-A-A-T-T-C-G-C-G double helix containing a G·T base pair and the dC-G-C-A-G-A-A-T-T-C-G-C-G double helix containing an extra adenine (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 1235-1246 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of helix formation were investigated using the temperature-jump technique for the following two molecules: dC-G-T-G-A-A-T-T-C-G-C-G, which forms a double helix containing a G·T base pair(the G·T 12-mer), and dC-G-C-A-G-A-A-T-T-C-G-C-G, which forms a double helix containing an extra adenine (the 13-mer). When data were analyzed in an all-or-none model, the activation energy for the helix association process was 22 ± 4 kcal/mol for the G·T 12-mer and 16 ± 7 kcal/mol for the 13-mer. The activation energy for the helix-dissociation process was 68 ± 2 kcal/mol for the G·T 12-mer and 74 ± 3 kcal/mol for the 13-mer. Rate constants for recombination were near 105s-1M-1 in the temperature range from 32 to 47°C; for the dissociation process, the rate constants varied from 1s-1 near 32°C to 130s-1 near 47°C. Possible effects of hairpin loops and fraying ends on the above data are discussed.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/bip.360220415
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    Raman spectra and normal vibrations of dipeptides. II. Glycyl-L-proline (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 1285-1300 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Raman and ir spectra of the glycyl-L-proline (GP) dipeptide were recorded. A normal-coordinate treatment was performed on the basis of the experimental spectra, using a modified Urey-Bradley force field (MUBFF). Cyclic redundancies were eliminated, and those due to the ring methylene groups, particularly distorted in regard to the tetrahedral conformation, were treated. An assignment of the experimental frequencies is proposed on the basis of the normal treatment.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/bip.360220504
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  • 144
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    Secondary structure of peptides. 4: 13C-Nmr CP/MAS investigation of solid oligo- and poly(L-alanines) (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 1357-1372 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Primary and tertiary amine-initiated polymerizations of L-alanine-N-carboxyanhydride (L-Ala-NCA) were conducted at 20 or 100°C in a variety of solvents. The 75.5-MHz 13C-nmr CP/MAS spectra of the resulting poly(L-alanines) revealed that all samples contain both α-helix and pleated-sheet structures. Depending on the reaction conditions the α-helix content varied between ca. 1 and 99%. Reprecipitation from aprotic nonsolvents does not change the α-helix/β-sheet ratio, indicating that this ratio is thermodynamically controlled. Since relatively large amounts of oligopeptides of degree of polymerization (DP) 4-6 can be extracted by means of acetic acid, it is concluded that (a) most poly(L-alanines) possess a bimodal molecular weight distribution, (b) the oligopeptide fraction with DP ≤ 11 is responsible for the β-sheet fraction of all samples, and (c) the two-stage crystal growth proposed by Komoto and Kawai is not correct. Solubilizing initiators such as poly(ethylene oxide) NH2 prevent the precipitation of oligoalanine and, thus, the formation of a β-sheet structure. 13C-nmr CP/MAS measurements also show that tri- and tetra-L-alanines form insoluble β-sheet structures.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/bip.360220508
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    Synthesis and conformation of the cyclic octapeptides cyclo(Phe-Pro)4, cyclo(Leu-Pro)4, and cyclo[Lys(Z)-Pro]4 (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 2191-2206 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cyclic octapeptides, cyclo(X-Pro)4, where X represents Phe, Leu, or Lys(Z), were synthesized and their conformations investigated. A C2-symmetric conformer containing two cis peptide bonds was found in all of these cyclic octapeptides. The numbers of available conformations due to the cis-trans isomerization of Pro peptide bonds depended on the nature of the solvent and X residue: they decreased in the following order: cyclo[Lys(Z)-Pro]4 〉 cyclo(Leu-Pro)4 〉 cyclo(Phe-Pro)4 in CDCl3. 13C spin-lattice relaxation times (T1) of these cyclic octapeptides were measured, and the contribution of segmental mobility to T1 was found to vary with the nature of the X residue.
    Additional Material: 12 Ill.
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    URL: http://dx.doi.org/10.1002/bip.360221006
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    Apparent molar volumes of some amino acids and peptides in aqueous urea solutions (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 2397-2409 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Densities of solutions of several α-amino acids and peptides in 3 and 6m aqueous urea solvents have been determined at 298.15 K. These data have been used to evaluate the infinite-dilution apparent molar volumes of the solutes and the volume changes due to transfer (Vtr0) of the α-amino acids and peptides at infinite dilution from water to aqueous urea solutions. The sign and magnitude of the Vtr0 values have been rationalized in the framework of Friedman's cosphere-overlap model. The Vtr0 values for the glycyl group (—CH2CONH—) and alkyl side chains have been estimated.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/bip.360221107
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    Influence of conformation on the fluorescence of tryptophan-containing peptides (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 2459-2476 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Conformational-energy calculations of the zwitterionic forms of Trp, Gly-Trp, Pro-Trp, Phe-Trp, Trp-Gly, Trp-Phe, Trp-Trp, and Trp-Gly-Gly were done using an empirical energy program for peptides (ECEPP). The resulting low-energy conformations were analyzed for the presence of hydrogen bonds, the distances between carbonyl groups and the indole ring, the distances between the N-terminal amino group and the indole ring, the dihedral angle between the planes containing carbonyl groups and the indole ring, and for dipeptides with two aromatic side chains, the dihedral angle and distance between the planes of the aromatic rings. This information was correlated with literature data from x-ray crystallographic studies, fluorescence lifetime studies, and quantum-yield experiments; proposed models of intramolecular quenching are discussed in light of the peptide conformations.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/bip.360221111
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    19F-NMR study of DNA bis-intercalation (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 2497-2500 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/bip.360221202
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    Geometry and mechanics of DNA superhelicity (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 2477-2495 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This paper analyzes the elastic equilibrium conformations of duplex DNA constrained by the constancy of its molecular linking number, Lk. The DNA is regarded as having the mechanical properties of a homogeneous, linearly elastic substance with symmetric cross section. Integral representations of the writhing number Wr and of Lk are developed, in terms of which the equilibria are given as solutions to an isoperimetric problem. It is shown that the Euler angles defining equilibrium conformations must obey equations identical to those governing unconstrained equilibria. A scaling law is developed stating that molecules supercoiled the same amount ΔLk will have geometrically similar elastic equilibria regardless of their length. Thus, comparisons among molecules of properties related to their large-scale tertiary structure should be referred to differences in ΔLk rather than to their superhelix densities. Specific conditions on the elastic equilibrium conformations are developed that are necessary for ring closure. The equilibrium superhelical conformations accessible to closed-ring molecules are shown to approximate toroidal helices. Questions relating to the stability and nonuniqueness of equilibria are treated briefly. A comparison is made between these toroidal conformations and interwound configurations, which are shown to be stable, although they are not equilibria in the present sense. It is suggested that entropic factors are responsible for favouring the toroidal conformation in solution.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/bip.360221112
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    Conformation and folding in histones H1 and H5 (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 113-118 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Denatured histones H1 and H5 can be readily refolded on salt addition. Their digestion by trypsin leads to limit peptides of about 80 residues having the same nmr and CD spectra as those of the intact parent histones. Scanning microcalorimetry shows that (1) the folded structures of H1 and H5 are located entirely in their limit peptides; (2) both have values of the specific denaturation enthalpy typical for small globular proteins; and that (3) both exhibit a classic “2-state” transition (ΔHdcal = ΔHdvan't Hoff). The heat-denaturation profiles of H5 measured using intrinsic and extrinsic Cotton effect and side-chain nmr peaks do not coincide at all. Only the intrinsic Cotton effects give a Tm and ΔHdvan't Hoff close to that from microcalorimetry. We conclude that these proteins exhibit large-scale side-chain motions that precede the macroscopic cooperative transition.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/bip.360220118
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    Cis-trans peptide-bond equilibria in cyclic hexapeptides (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 153-156 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Data are presented on the position of the equilibria of cyclo(Xxx-Pro-Yyy)2 backbones between forms with two cis Xxx-Pro peptide bonds and forms with only trans peptide bonds. These data are interpreted in terms of two factors: a solvent-independent steric interaction between the Xxx and Pro side chains, and the ability of solvent to influence the transannular electrostatic interaction between N—H and C=O groups of the Xxx units in the all-trans form.
    Additional Material: 1 Tab.
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    URL: http://dx.doi.org/10.1002/bip.360220124
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    Influence of the peptide chain length on the stability of double-stranded β-helical species of D,L-alternating oligovalines in chloroform solution (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 157-161 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The type and distribution of the β-helixes occurring in chloroform solutions of Boc-(L-Val-D-Val)6-OMe and Boc-(L-Val-D-Val)8-OMe have been studied by using 1H-nmr techniques. Right- and left-handed ↑↓β4.4-helices and left-handed β5.6-helices occur with the dodecapeptide. β4.4-Helices of opposite handedness occur also with the hexadecapeptide, but ↑↓β5.6-helices could not be detected with this oligomer. At equilibrium, at 25°C, the double helix of the dodecapeptide is only moderately populated. These results indicate that increasing the chain length has a destabilizing effect on the ↑↓β5.6-helices of D,L-alternating oligovalines in chloroform solution.
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    Preferred conformations of peptides containing α,α-disubstituted α-amino acidsThis is part 97 of the “linear oligopeptide series.” For part 96, see Bonora, G. M., Moretto, V., Toniolo, C. & Mutter, M. (1982) submitted to Int. J. Pept. Protein Res. (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 205-215 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The conformational preferences of linear peptides containing α,α-disubstituted α-amino acids, derived from the crystal structures of 28 compounds, are reviewed. In particular, the sensitivity of peptide conformation to the geometry of these unusual amino acids is underlined. We also consider possible future directions of research, which, we hope, will result in a complete understanding of the structures adopted by peptaibol antibiotics.
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    URL: http://dx.doi.org/10.1002/bip.360220129
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    Stabilizing effects of 2-methylalanine residues on β-turns and α-helices (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 241-246 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 13C-, 1H-nmr, CD, and x-ray crystallography revealed β-turns of type III for Boc-Gly-L-Ala-Aib-OMe, Boc-L-Ala-Aib-L-Ala-OMe; the 310-helix for Boc-Aib-L-Ala-Aib-L-Ala-Aib-OMe; and antiparallel arranged α-helices for Boc-L-Ala-Aib-Ala-Aib-Ala-Glu(OBzl)-Ala-Aib-Ala-Aib-Ala-OMe. An N-terminal rigid α-helical segment is found in the polypeptide antibiotics alamethicin, suzukacillin, and trichotoxin. The α-helix dipole is essential for their voltage-dependent pore formation in lipid bilayer membranes, which is explained by a flip-flop gating mechanism based on dipole-dipole interactions of parallel and antiparallel arranged α-helices within oligomeric structures.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/bip.360220133
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    Insulin's structural behavior and its relation to activity (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 281-291 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This paper discusses the hypothesis that insulin undergoes a conformational change either before or during its binding to the receptor. The evidence for this is not conclusive but allows us to reconcile the following observations: (1) no chemical modification or deletion of invariant surface residues has abolished the hormone's activity - only reduced its potency. (2) Reduction in potency follows many modifications to different side chains, both variant and invariant. (3) There are insulins with perfectly preserved structure (by the criteria of aggregation, spectroscopy, and x-ray analysis) that have markedly reduced potency. (4) Insulins with disturbed structure still exhibit real, sometimes substantial activity.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/bip.360220137
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    Refinement of the structure of bovine seminal ribonuclease (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 327-332 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We report here the refinement at 2.5-Å resolution of the x-ray crystal structure of bovine seminal ribonuclease, a dimeric covalent enzyme. The protein, which crystallizes with one molecule in the asymmetric unit, consists of two subunits of identical chemical sequences, related by an almost exact binary axis. The tertiary structure of the subunits is similar to that of the pancreatic enzyme, which shows similar catalytic properties. The refinement was carried out using the restrained least-squares procedure both in the reciprocal and real spaces. The assemblage of the subunits in the dimer is described and discussed.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/bip.360220142
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    Lateral and rotational diffusion of EGF-receptor complex: Relationship to receptor-mediated endocytosis (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 347-353 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The clustering and internalization of epidermal growth factor (EGF)-receptor complexes on human tumor cells are temperature-sensitive processes that are completely inhibited at 4°C. The rotational diffusion of EGF-receptor is limited by the viscosity of the lipid matrix, while additional constraints limit the lateral diffusion of the receptor molecule. Although the lateral and rotational diffusion of the occupied receptors are temperature sensitive, they do not provide a rate-determining factor for the clustering and subsequent internalization of the EGF-receptor. Even at 4°C the occupied receptors move quickly enough to allow the formation of EGF-receptor clusters. The lack of internalization at 4°C must be due to the inhibition of interactions other than a temperature effect on receptor mobility. EGF-induced receptor clustering involves the formation of microclusters composed of 10-50 receptor molecules.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/bip.360220145
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    Photo-CIDNP study of interactions of serine proteinases with their protein inhibitors (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 387-390 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Photochemically induced dynamic nuclear polarization was used to study the accessibility of surface tyrosine and tryptophan residues in proteinases, in their protein inhibitors and in the proteinase-inhibitor complexes. The accessibility probe is the triplet of 10-(carboxyethyl) flavin formed by optical excitation. On complex formation we observe accessibility loss in the surface tyrosines and tryptophans in the proximity of the proteinase-inhibitor contact site, and in the case of bovine pancreatic trypsin inhibitor, in more distant tyrosines as well.
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    URL: http://dx.doi.org/10.1002/bip.360220150
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    Peptides as channel-making ionophores: Conformational aspects (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 403-407 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The β62.4- and β126.6-helical structures do not appear consistent with the structural data and ion-transport properties of (Ala-Ala-Gly) or (Leu-Ser-Leu-Gly) oligomers. Oligoalanine derivatives also give rise to current fluctuations in bilayer lipid membranes. Bundles of molecules may explain the behavior of these various peptides in membranes.
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    URL: http://dx.doi.org/10.1002/bip.360220153
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    Contribution of synthetic polymers of amino acids to knowledge of immune response (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 441-452 
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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 synthetic random polymers poly(Glu,Lys,Phe), poly(Glu,Phe) and poly(Glu,Lys,Tyr), have been used to study some parameters associated with the genetic control of the immune response (Ir) of mice. Mice of haplotypes d and q respond well to GLPhe. Mice of haplotypes k and b were previously shown to be nonresponders, whereas the F1 (k × b) responded via a phenomenon involving “complementation” between 2 Ir genes, i.e., one gene product from IA, and another from IE form the requisite two-chain Ia “receptor” macromolecules (EbβEkα). When it was determined that mice of haplotypes q and k respond to GPhe, and the controlling gene maps to IA, (Aα Aβ), we tested the theory that mice having q and k alleles in IA might respond to GLPhe via recognition of GPhe determinants in the terpolymer. Employing the in vitro proliferative response to T-cells from mice immunized with GLPhe and stimulated with GPhe and GLT (cross-reaction), it was determined that different determinant selection patterns exist in the recognition of GLPhe. Mice having q and k alleles in IA can respond to GLPhe via one mechanism, and other mice having d and f alleles respond via other mechanisms. The F1 of the appropriate nonresponder strains forming the Ia molecule (EbβEkα) still exhibit the “complementation” phenomenon. Rabbit antibody against anti-GPhe (ID) from SWR mice (H-2q)(anti-ID) was prepared. This anti-ID strongly inhibited the binding of 125I-GPhe by anti-GPhe antisera produced only in mice of H-2q haplotype and had no effect on the binding of GPhe by anti-GPhe antisera produced in mice of other haplotypes. The anti-ID also inhibited the binding of 125I-GLPhe and 125I-GPhe by anti-GLPhe antisera produced only in mice of H-2q haplotype. These specificities were also confirmed by the inhibition of the plaque-forming cells. It was concluded that the antibodies produced in mice of H-2q haplotype against GPhe and GLPhe share common idiotypic determinants that are recognized by the anti-idiotypic antiserum.
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    URL: http://dx.doi.org/10.1002/bip.360220157
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    Immunoassays of peptide hormones and their chemical aspects (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 481-486 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The N-terminal maleoyl-β-alanyl derivative of human gastrin-[2-17] has been synthesized as a model compound to investigate the usefulness of such peptide derivatives for their mild and selective conjugation, via reaction with thiol groups, to high-molecular-weight carrier molecules to produce antigens, as well as to radioiodinable or fluorogenic molecules to prepare tracers for immunoassays. In this context the examined enzyme substrate-gastrin conjugate was found to exhibit the full immunoreactivity of the parent peptide and to be well suited as tracer in a gastrin fluorescence-immunoassay.
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    URL: http://dx.doi.org/10.1002/bip.360220161
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  • 162
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    Field desorption mass spectra of dermorphin and some related peptides (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 487-491 
    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.360220162
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  • 163
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    Controlled release of macromolecules and pharmaceuticals from synthetic polypeptides based on glutamic acid (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 547-556 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Biocompatible, biodegradable copolymers of glutamic acid and ethyl glutamate were evaluated for their permeability to proteins ranging in molecular weight from 12,300 to 69,000. The results showed that the copolymers were sufficiently permeable that they could be used for the preparation of implantable, controlled-release systems capable of releasing therapeutic amounts of high-molecular-weight drugs.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360220167
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  • 164
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    Temperature dependence of the diffusion coefficient of polystyrene latex spheres (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 593-595 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360220203
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  • 165
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    Conformational study of ribonucleotides, 2′-deoxyribonucleotides, and arabinonucleotides by carbon-13 nuclear magnetic resonance (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 605-616 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The geminal and vicinal 13C-31P coupling constants have been monitored, as a function of pH, for a series of uracil and cytosine 3′- and 5′-nucleotides with a ribose, arabinose, or 2′-deoxyribose sugar. Data were also obtained for two 3′,5′-diphosphates in the ribose and arabinose series. The geminal J(C5′-P5′) and J(C3′-P3′) couplings show only a small dependence on the ionization state of the phosphate, decreasing by 〈 0.5 Hz in the pH 5-7 range. For the ribose and arabinose 3′-nucleotides, the vicinal J(C4′-P3′) increase (up to 1.5 Hz) on secondary phosphate ionization in the pH 5-7 range, whereas their J(C2′-P3′) couplings decrease (up to 1.5 Hz) over the same pH range. In contrast for the 2′-deoxyribose molecules, both couplings decrease (∼0.5 Hz) on phosphate ionization. The titration curves provide information about the influence of the sugar on the conformation about the C3′—O3′ bond. Some conformational trends could be rationalized by consideration of the sugar-puckerdependent contact interactions between the 3′-phosphate and the substituents on the furanose ring.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360220206
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  • 166
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    Copolymerization kinetics of N-carboxyanhydrides of some α-amino acids: Influence of nature of amino acids (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 747-753 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Studies on copolymerization kinetics of N-carboxyanhydride (NCA) of O-acetyl-L-tyrosine (T) with NCAs of L-valine (V) and glycine (G) were carried out in dioxane at 25°C with n-butylamine as initiator. The reactivity ratios for the VT system were found to be rV:rT:0.57:0.22; and for the GT system, rG:rT:0.26:0.42. A comparison of this data with that obtained when L-analine was used in place of L-valine or glycine showed that in the three systems, the reactivity ratio of the amino acid residue with a greater tendency to form ordered secondary structure was greater than that of its comonomer. Among the variable comonomers (glycine, L-alanine, L-valine) of O-acetyl-L-tyrosine, it is again L-alanine, whose tendency to form helical structure is very high, that has the greater reactivity ratio.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360220213
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  • 167
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    Conformation of the central sequence of angiotensin II and analogs (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 663-687 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We describe the synthesis and the conformational analysis by ir, CD, and proton-nmr spectroscopy of four model peptides of the type N-Ac-Tyr-X-His-NH2 with X = Val, Leu, Ala, Gly. These peptides represent the central sequence of the hormone angiotensin II and its position-5 analogs. We studied their conformational behavior in aqueous solution during pH titration and in organic solvents. For specific purposes of spectral analysis (ir band assignment, proton-nmr signal assignment, heteronuclear vicinal coupling constants), we synthesized three isotopically enriched homologs of the mother sequence, i.e., N-Ac-(15N-Tyr)-Val-His-NH2, N-Ac-(13C, 2H, Tyr)-Val-His-NH2, and N-Ac-Tyr-(13C, 2H, Val)-His-NH2. Results are summarized as follows: the tyrosine and the histidine side chains influence each other through space; this mutual influence is modulated by the nature of the side chain in position X and decreases in going from X=Val to X=Gly as a consequence of two simultaneous events, changes in the side-chain rotamer distribution and changes in the ϕ and ψ angles of residue X. The decrease in the bulkiness of the side-chain X (Val → Gly) leads to increased flexibility of the peptide backbone at this site, which is also reflected in the apparent ratio of C5, C7, and intermediate conformations present in equilibrium. The three spectroscopic techniques, in addition to the results of chymotryptic degradation experiments, show a high level of agreement, and all reflect the dynamic conformation of these peptides in a different manner.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360220210
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  • 168
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    Assignment of the amide and aromatic protons of the CHA2-dodecapeptide α-factor from S. Cerevisiae (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 815-820 
    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.360220304
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  • 169
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    Cycloadditionsreaktionen von Heterocumulenen, XXVI. Cycloaddukte aus Arylisothiocyanaten und 2,2-disubstituierten Enaminen (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 55-65 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Cycloaddition Reactions of Heterocumulenes, XXVI. Cycloadducts from Aryl Isothiocyanates and 2,2-Disubstituted EnaminesAryl isothiocyanates 1 react with enamines 2 to give two types of 2:1 cycloadducts. Below 50°C, 1a - g and 2 give rise to 6-imino-1,3-thiazine-2-thiones 5, the constitutions of which are proved by an X-ray analysis of 5c. Above 50°C or starting from 4-nitrophenyl isothiocyanate (1h),2,4-dithiouracils 6 are formed. 1:1 cycloadducts of the reactants are detected spectroscopically; on workup, they hydrolyze to give 2-formylthiopropionanilides 9.
    Notes: Arylisothiocyanate 1 und Enamine 2 reagieren zu zwei Typen von 2:1-Cycloaddukten. Unterhalb von 50°C entstehen aus 1a - g und 2 6-Imino-1,3-thiazin-2-thione 5, deren Konstitution durch die Röntgenstrukturanalyse von 5c bewiesen wurde. Oberhalb 50°C oder aus 4-Nitrophenylisothio-cyanat (1h) bilden sich 2,4-Dithiouracile 6. 1:1-Cycloaddukte der Reaktanten lassen sich spektroskopisch nachweisen; bei der Aufarbeitung hydrolysieren sie zu 2-Formylthiopropionaniliden 9.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19831160107
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  • 170
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    Kristall- und Molekularstruktur des Antharachinonophans [2.0.0](1,4)Benzeno(1,8)anthrachinono(1,4)benzenophan (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 544-548 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Crystal and Molecular Structure of the Anthraquinonophane [2.0.0](1,4)Benzeno(1,8)anthraquinono(1,4)benzenophaneBoth phenylene rings in the [5.2]paracyclophane subunit of the anthraquinonophane [2.0.0](1,4)benzeno(1,8)anthraquinono(1,4)benzenophane (1) are tilted by 37.6°. They show a boat-like deformation. The carbonyl group pointing towards the interior of the molecule interacts with the paracyclophane system. From this a strong boat-like deformation of the quinone ring of the anthraquinone moiety results.
    Notes: Die beiden Phenylenringe in der [5.2]Paracyclophan-Untereinheit des [2.0.0](1,4)Benzeno(1,8)-anthrachinono(1,4)benzenophans (1) sind um 37.6° gegeneinander geneigt und wannenförmig deformiert. Die Wechselwirkungen der ins Molekülinnere zeigenden Carbonylgruppe mit dem Paracyclophan-System verursachen eine starke wannenförmige Deformation des Chinonringes in der Anthrachinon-Einheit.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19831160216
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  • 171
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    Vier- und fünfgliedrige Phosphorheterocyclen, 55. 1,2,4-Diazaphospholo-[1,2,3]diazaphosphole - Bildung durch Phosphaalken + Nitrilimin-Cycloaddition, Zerfall durch Nitril-Eliminierung und Strukturvergleich von Addend und Addukt (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 549-562 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Four- and Five-membered Phosphorus Heterocycles, 55. 1,2,4-Diazaphospholo-[1,2,3]diazaphospholes - Preparation by Phosphaalkene + Nitrilimine Cycloaddition, Decomposition by Nitrile Elimination, and Structural Comparison of Addend and Adduct2,5-Dimethyl-1,2,3-diazaphosphole (1a) reacts with N-Phenylbenzohydrazonoyl chloride (6a) and a base in a sequence of nitrilimine cycloaddition, benzonitrile elimination, and another cycloaddition to give in the second step the 4-anilino derivative 7 of 1a, in the first and third step the 7a-unsubstituted and 7a-anilino-substituted title compound, 3a and 8, respectively. - As shown by the molecular structures, determined by X-ray analysis, there is a 6 π delocalization in 7 which is lost in 8 with remarkably little geometrical change at the phosphorus. - Other nitrilimines add to 1a in the same direction, that is with PC- and CN-bond formation.
    Notes: 2,5-Dimethyl-1,2,3-diazaphosphol (1a) reagiert mit N-Phenylbenzohydrazonoylchlorid (6a) und einer Base in einer Folge von Nitrilimin-Cycloaddition, Benzonitril-Eliminierung und neuerlicher Cycloaddition. In der zweiten Stufe bilden sich dabei das 4-Anilinoderivat 7 von 1a, in der ersten und dritten Stufe entstehen die 7a-unsubstituierte und 7a-anilinosubstituierte Titelverbindung, 3a bzw. 8. - Die röntgenographisch bestimmten Molekülstrukturen zeigen für den Übergang von 7 in 8 die Aufhebung einer 6 π-Delokalisierung bei nur geringen geometrischen Veränderungen am Phosphor. - Auch andere Nitrilimine addieren sich an 1a in gleicher Richtung, also unter PC- und CN-Verknüpfung.
    Additional Material: 6 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19831160217
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  • 172
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    Thermolyse von Ansaran, Ansaren und Cuban (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 1415-1421 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Thermolysis of Ansarane, Ansarene and CubaneThe thermolysis and kinetics of decomposition of cubane 4 and of ring enlarged cubanes, the ansaranes 1 - 3, are described. The relief of strain which will be observed breaking specific bonds has been estimated by the aid of force-field calculations thereby disclosing probable reaction pathways. The gas phase pyrolysis of cubane 4 yields vibrationally excited cyclooctatetraene 5 which fragmentates to benzene and acetylene. The gas kinetics of cyclooctatetraene 5 is reported on as well.
    Notes: Die Thermolyse und Zerfallskinetik ringerweiterter Cubane, der Ansarane 1 - 3, sowie des Cubans 4 selbst, werden beschrieben. Mit Hilfe von Kraftfeldrechnungen wird die Spannungserleichterung beim Bruch bestimmter Bindungen abgeschätzt, und wahrscheinliche Thermolysewege werden aufgezeigt. Das bei der Gasphasenthermolyse von Cuban 4 gebildete schwingungsangeregte Cyclooctatetraen 5 fragmentiert zu Benzol und Acetylen. Über die Gasphasenkinetik von Cyclooctatetraen wird ebenfalls berichtet.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19831160417
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  • 173
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    Zur Existenz eines Silaolefins: Synthese und Kristallstrukturen von Wittig- und Diels-Alder-Produkten in Reaktionen lithiierter fluorsilylfunktioneller Diazasilacyclopentene mit Benzaldehyd und Methacrolein (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 282-289 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On the Existence of a Silaolefin: Synthesis and Crystal Structures of Wittig and Diels-Alder Products in Reactions of Lithiated (Fluorosilyl)diazasilacyclopentenes with Benzaldehyde and MethacroleinLithium salts of 1,2-diaza-3-sila-5-cyclopentenes react with fluorosilanes and aminofluorosilanes to give 4-(fluorosilyl)-substituted compounds 1 - 4. By reaction with tert-butyllithium 1 - 4 themselves form lithium salts 5 - 8, which react with fluorosilanes in a second substitution giving 9 and 10.5 and 7 undergo a Wittig-type reaction with benzaldehyde to form the benzylidene derivative 11. Spirocyclic Diels-Alder adducts (12, 13) are obtained from the reaction of 5 and 6 with 2-methyl-2-propenal. The propenylidene derivative 14 is formed as a by product. With excess 2-methyl-2-propenal, 12 reacts as a dienophile giving the oligocyclic Diels-Alder adducts 15 and 16. The crystal structures of 11 and 15 are reported.
    Notes: Lithiumsalze der 1,2-Diaza-3-sila-5-cyclopentene reagieren mit Fluorsilanen und Aminofluorsilanen zu den 4-(Fluorsilyl)-substituierten Verbindungen 1 - 4. In Reaktion mit tert-Butyllithium bilden 1 - 4 erneut Lithiumsalze (5 - 8), die mit Fluorsilanen unter Zweitsubstitution zu 9 und 10 reagieren. In Wittig-analoger Reaktion reagieren 5 und 7 mit Benzaldehyd zum Benzyliden-Derivat 11. Spirocyclische Diels-Alder-Addukte (12, 13) werden aus 5 und 6 mit 2-Methyl-2-propenal erhalten. Als Nebenprodukt entsteht das Propenyliden-Derivat 14. Mit überschüssigem Dien (2-Methyl-2-propenal) reagiert 12 als Dienophil zu den oligocyclischen Diels-Alder-Addukten 15 und 16. Kristallstrukturen von 11 und 15 werden mitgeteilt.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19831160132
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  • 174
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    Synthese cyclischer Silylhydrazine - Kristallstruktur eines fünfgliedrigen Kreuz-Dimeren (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 290-298 
    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 Cyclic Silylhydrazines - Crystal Structure of a Five-membered Cross Dimerisation ProductN,N-Bis(fluorosilyl)amines (1 - 3) react with dilithiated hydrazines to give four- and five-membered silylhydrazine rings (4 - 8). The isomerisation of a 3-(tert-butylamino)-1,3-diaza-2,4-disilacyclobutane (8) to a 1,2,4-triaza-3,5-disilacyclopentane (9) has been demonstrated. Lithium salts of silylhydrazines react with fluorosilanes to give substitution products (10 - 15). Dilithiated hydrazine reacts with Me2SiF2 yielding N(SiFMe2)3 (16). The formation of isomeric N-(fluorosilyl)-N,N′-bis(trimethylsilyl)- and N′-(fluorosilyl)-N,N-bis(trimethylsilyl)hydrazines has been accomplished via ring-closure reactions (17 - 19) and confirmed by the crystal structure determination of a five-membered ring cross dimer (19). The ten-membered bicyclic ring system (22) is obtained by the reaction of (14) with dilithiated hydrazine.
    Notes: N,N-Bis(fluorsilyl)amine (1 - 3) reagieren mit dilithiierten Hydrazinen zu vier- und fünfgliedrigen Silylhydrazinringen (4 - 8). Präparativ gelang der Nachweis der Isomerisierung eines 3-(tert-Butylamino)-1,3-diaza-2,4-disilacyclobutans (8) zum 1,2,4-Triaza-3,5-disilacyclopentan (9). Lithiumsalze von Silylhydrazinen reagieren mit Fluorsilanen unter Substitution (10 - 15). Dilithiiertes Hydrazin reagiert mit Me2SiF2 zu N(SiFMe2)3 (16). Die Bildung von isomeren N-(Fluorsilyl)-N,N′-bis(trimethylsilyl)- und N′-Fluorsilyl-N,N-bis(trimethylsilyl)hydrazinen wird durch Ringschlußreaktionen (17 - 19) nachgewiesen und durch die Kristallstrukturuntersuchung eines Kreuz-Dimeren-Fünfrings belegt (19). Der zehngliedrige Bicyclus 22 entsteht in der Reaktion des N,N′-Bis(fluordimethylsilyl)-N,N′-bis(trimethylsilyl)hydrazins(14) mit dilithiiertem Hydrazin.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19831160133
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  • 175
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    Synthese und Umlagerung substituierter Bicyclo[2.1.0]pent-2-ene. Eine thermische „walk“-Umlagerung (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 299-322 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis and Rearrangement of Substituted Bicyclo[2.1.0]pent-2-enes. A Thermal “Walk”-RearrangementThe synthesis and the thermal behaviour of methyl 5-methyl-, 1,5-, and 2,5-dimethylbicyclo-[2.1.0]pent-2-ene-5-carboxylates 3a, b, 4a, b, 5a, b, as well as of 1,5- and 2,5-dimethylbicyclo-[2.1.0]pent-2-ene-5-carbonitriles 6a, 7a, b are reported. The “walk”-rearrangement which is degenerate in the cases of 3a, b could be detected experimentally with the aid of the dimethyl derivatives 4a, b, 5a, b, 6a, and 7a, b. Electrocyclic ring opening to the correspondingly substituted 1,3-cyclopentadienes competes with the “walk”-rearrangements. Already at 0°C the “walk”-rearrangements 4a → 5a, 4b → 5b, and 6a → 7a proceed stereospecifically with inversion at the migrating carbon atom C-5 as postulated by Woodward and Hoffmann (0°C: ΔG* = 21.7, 24.8, and 21.9 kcal/mol). We assume that the surprisingly low activation barriers do not only result from the resonance stabilization of an aromatic transition state but largely from the anomalously high ground-state enthalpy of the bicyclopentene system.
    Notes: Synthese und thermisches Verhalten der 5-Methyl-, 1,5-Dimethyl- und 2,5-Dimethylbicyclo-[2.1.0]pent-2-en-5-carbonsäure-methylester 3a, b, 4a, b, 5a, b und -carbonitrile 6a, 7a, b werden beschrieben. Die in den Systemen 3a, b strukturell entartete „walk“-Umlagerung konnte am Beispiel der Dimethylderivate 4a, b, 5a, b, 6a und 7a, b experimentell nachgewiesen werden. Dazu konkurrierend finden elektrocyclische Ringöffnungen zu den entsprechend substituierten 1,3-Cyclopentadienen statt. Die „walk“-Umlagerungen 4a → 5a, 4b → 5b und 6a → 7a erfolgen bereits bei 0°C stereospezifisch mit der von Woodward und Hoffmann postulierten Inversion am wandernden Kohlenstoff C-5 (0°C: ΔG* = 21.7, 24.8 bzw. 21.9 kcal/mol). Vermutlich resultieren die überraschend niedrigen Aktivierungsbarrieren nicht allein aus der Resonanzstabilisierung eines aromatischen Übergangszustandes, sondern wesentlich aus der anomal hohen Grundzustandsenthalpie des Bicyclopentensystems.
    Additional Material: 7 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19831160134
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    Übergangsmetall-substituierte Phosphane, Arsane und Stibane, XXXIII. (Brommethyl)bis[(trimethylsilyl)methyl]arsan: Darstellung und Metallierung zu Komplexen mit η1 - oder η2-koordiniertem Arsinomethyl-Liganden (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 348-359 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Transition Metal Substituted Phosphanes, Arsanes, and Stibanes, XXXIII. (Bromomethyl)bis[(trimethylsilyl)methyllarsane: Synthesis and Metalation to Complexes with η1- or η2-Coordinated Arsinomethyl LigandThe pyrolysis of the trialkyldibromoarsorane (Me3SiCH2)3AsBr2 (1) under reduced pressure yields the (bromomethyl)arsane (Me3SiCH2)2AsCH2Br (2) with Me3SiBr elimination via the intermediate formation of the bromodialkylmethylenearsorane Br(Me3SiCH2)2As=CH2. 2 reacts with Na[M(CO)3Cp] (M=Mo, W) to give the transition metal substituted arsanes Cp(CO)3M-CH2As(CH2SiMe3SiMe3)2 (3a,b). These undergo cyclisation with loss of CO and formation of Cp(CO)2M[η2 CH2As(CH2SiMe3)2] (4a,b), the first complexes with an η2-bound arsinomethyl unit, either spontaneously (3a) or upon ultraviolet irradiation or prolonged standing at room temperature (3b). MeI quaternizes the arsane 3b to give the metalated arsonium salt [Cp(CO)3W - CH2As(Me)(CH2SiMe3)2]I (5). The NMR spectra indicate fluxional behaviour for the chiral metallacycles 4a, b. It is caused by a rapid change of the configuration at the metal centre, for which a mechanism, involving a rotation of the dihapto-coordinated ligand about an axis defined by the metal and the centre of the As—C(M) bond, is suggested.
    Notes: Die Pyrolyse des Trialkyldibromarsorans (Me3SiCH2)3AsBr2 (1) bei reduziertem Druck liefert unter Me3SiBr-Eliminierung über die intermediäre Stufe eines Bromdialkylmethylenarsorans Br(Me3SiCH2)2)2As=CH2 das (Brommethyl)arsan (Me3SiCH2)2AsCH2Br (2). Dieses reagiert mit Na[M(CO)3Cp] (M=Mo, W) zu den Übergangsmetall-substituierten Arsanen Cp(CO)3M-CH2As(CH2SiMe3)2 (3a,b), welche sich spontan (3a) bzw. bei UV-Bestrahlung oder längerem Stehenlassen bei Raumtemperatur (3b) unter CO-Verlust in Cp(CO)2M[η2-CH2As(CH2SiMe3)2] (4a,b), die ersten Komplexe mit η2-gebundener Arsinomethyl-Einheit, umwandeln. MeI quartärisiert das Arsan 3b zum metallierten Arsoniumsalz [Cp(CO)3W - CH2As(Me)(CH2SiMe3)2]I (5). Die NMR-Spektren zeigen für die chiralen Metallacyclen 4a, b fluktuierendes Verhalten an. Als Mechanismus für den dafür verantwortlichen schnellen Konfigurationswechsel am Zentralmetall wird die Rotation des dihapto-koordinierten Liganden um eine durch das Metall und den Mittelpunkt der As—C(M)-Bindung verlaufende Achse vorgeschlagen.
    Additional Material: 2 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19831160136
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    Nachweis von 4-Homocubyl-Carbenium-Ionen als reaktive Zwischenstufen (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 360-366 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Evidence for 4-Homocubyl Carbenium Ions as Reactive Intermediates4-(Hexafluoroisopropoxy)homocubane (6) is the main product of the thermolysis reaction of N-(4-homocubyl)-N-nitrosoacetamide (9) and of the solvolysis reaction of 4-homocubyl bromide (5) in hexafluoro-2-propanol. This is experimental evidence for 4-homocubyl carbenium ions as intermediates in both reactions. The solvolysis rate of 4-homocubyl bromide at 120°C in the same solvent (k1120°C=1.3 · 10-7s-1) by far exceeds that of 1-norbornyl bromide which does not react at a detectable rate under these conditions. According to force field calculations the strain enthalpy is increasing by as much as 66 kcal · mol-1 in the ionisation of 4-homocubyl bromide. Therefore nonclassical stabilization of the 4-homocubyl carbenium ion is postulated.
    Notes: Bei der Thermolyse von N-(4-Homocubyl)-N-nitrosoacetamid (9) und bei der Solvolyse von 4-Homocubylbromid (5) in Hexafluor-2-propanol entsteht 4-(Hexafluorisopropoxy)homocuban (6) als Hauptprodukt. Dies beweist das Auftrete von 4-Homocubyl-Carbenium-Ionen als Zwischenstufen beider Reaktionen. Die Solvolysegeschwindigkeit von 4-Homocubylbromid bei 120°C in Hexafluor-2-propanol (k1120°C = 1.3 · 10-7 s-1) ist wesentlich höher als die von 1-Norbornylbromid, dessen Solvolyse unter diesen Bedingungen nicht nachweisbar ist. Da die Ionisation von 4-Homocubylbromid nach Kraftfeldrechnungen mit 66 kcal · mol-1 Ansteigen an Spannungsenthalpie verbunden ist, wird für das 4-Homocubyl-Carbenium-Ion eine nichtklassische Stabilisierung angenommen.
    Additional Material: 2 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19831160137
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  • 178
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    Synthesen mit aliphatischen Dialdehyden, XXXVII. Darstellung, Struktur und Eigenschaften eines [3.3.3]Decamethinium-Cyaninfarbstoffes mit Indolin-Endgruppen (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 1982-2000 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Syntheses with Aliphatic Dialdehydes, XXXVII, Synthesis, Structure, and Properties of a [3.3.3.]Decamethinium Cyanine Dye, with Indoline End GroupsThe reaction of the trisaldehyde trisacetal 4 with 1,3,3-trimethyl-2-methyleneindoline (7) and its tetrafluoroborate 8 yields either the δ-substituted heptamethinium cyanine dye 9 or the [3.3.3]decamethinium cyanine dye 10, depending on the reaction conditions. Configuration and conformation of both polymethine dyes have been determined by means of spectroscopic data as well as by X-ray analyses. - The UV/Vis-spectroscopic 〈trimethine shift“ of trinuclear, Y-Conjugated, methinylogous guanidinium ions is compared with the “vinylene shift” of dinuclear, linear-conjugated, vinylogous amidinium ions (Table 1).
    Notes: Durch Umsetzung des Trisaldehyd-trisacetals 4 mit 1,3,3-Trimethyl-2-methylenindolin (7) und dessen Tetrafluoroborat 8 werden je nach Reaktionsbedingungen entweder der δ-substituierte Heptamethinium-Cyaninfarbstoff 9 oder der [3.3.3]Decamethinium-Cyaninfarbstoff 10 erhalten. Konfiguration und Konformation beider Polymethinfarbstoffe werden spektroskopisch sowie durch Röntgenstrukturbestimmungen ermittelt. - Der UV/Vis-spektroskopische „Trimethinsprung“ trinuclearer, Y-konjugierter, methinyloger Guanidinium-Ionen wird mit dem „Vinylensprung“ dinuclearer, linear-konjugierter, vinyloger Amidinium-Ionen verglichen (Tab. 1).
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19831160525
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  • 179
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    Übergangsmetall-Schwefelylid-Komplexe, XVIII. Die Deoxygenierung von anti-Tricarbonyl(1-methyl-3,5-diorganyl-λ6- thiabenzoloxid)chrom, -molybdän und -wolfram als neuartiger Weg zu λ4-Thiabenzol-Komplexen (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 2022-2027 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Transition Metal Sulfur Ylide Complexes, XVIII. The Deoxygenation of anti-Tricarbonyl(1-methyl-3,5-diorganyl-λ6thiabenzene oxide)chromium,-molybdenum, and -tungsten as a Novel Synthetic Route to λ4-Thiabenzene ComplexesFrom the reaction of anti-configurated λ6-thiabenzene oxide complexes 5a-e, 6e, and 7e with sodium bis(2-methoxyethoxy)aluminium hydride λ4-thiabenzene complexes 2a-e, 3e, and 4a are obtained. The hitherto unknown ylidic heterocycles in the novel complexes behave as significantly stronger donor ligands as the related λ6-thiabenzene oxides as is inferred from spectroscopic data.
    Notes: Bei der Reaktion der anti-Konfigurierten λ6-Thiabenzoloxid-Komplexe 5a-e, 6e und 7e mit Natrium-bis(2-methoxyethoxy)aluminiumhydrid werden die λ4-Thiabenzol-Komplexe 2a-e, 3e und 4e erhalten. Nach den Spektren sind die bisher unbekannten ylidischen Heterocyclen in den neuartigen Komplexen deutlich stärkere Donorliganden als die entsprechenden λ6-Thiabenzoloxide.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19831160528
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  • 180
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    Über die Reduktion des Benzvalenozonids zum cis-1,3-Cyclobutandimethanol mit LiAlH4 (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 669-680 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On the Reduction of Benzvalene Ozonide to cis-1,3-Cyclobutanedimethanol with LiAIH4On treatment with LiAlH4 at -30°C the polymeric ozonide of benzvalene (1) gives bicyclo-[1.1.0]butane-endo,endo-2,4-dimethanol (7). At higher temperatures cis-1,3-cyclobutanedimethanol (4) is formed. The stereochemical course of this unusual C—C hydrogenolysis has been elucidated by means of deuterated substrates. For this purpose a complete analysis of the 1H NMR spectra of the labeled cis-1,3-cyclobutanedicarboxylic anhydrides 9a-c had to be carried out. The dialcohol 7 and its bismethyl ether 16 add thiophenol across the central bond to form the cis products 18 and 19, respectively. Acids or Ag+ ions isomerize 7 via cleavage of a lateral bond into the ethers 21.
    Notes: Das polymere Ozonid des Benzvalens (1) wird mit LiAlH4 bei -30°C in Bicyclo[1.1.0]butan-endo,endo-2,4-dimethanol (7) übergeführt, bei höherer Temperatur entsteht cis-1,3-Cyclobutan-dimethanol (4). Mit deuterierten Verbindungen wurde der stereochemische Ablauf dieser ungewöhnlichen C—C-Hydrogenolyse aufgeklärt. Dazu mußte eine vollständige Analyse der 1H-NMR-Spektren der markierten cis-1,3-Cyclobutandicarbonsäureanhydride 9a-c durchgeführt werden. 7 und sein Bismethylether 16 addieren an der zentralen Bindung Thiophenol zu den cis-Produkten 18 bzw. 19. Säure oder Ag+-Ionen überführen 7 unter Öffnung einer seitlichen Bindung in die Ether 21.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19831160225
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  • 181
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    Das Photoelektronenspektrum von 1,1-Diethoxy-3,3-bis(trifluormethyl)allen. Der Effekt von Trifluormethylgruppen auf kumulierte Systeme (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 2888-2895 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The Photoelectron Spectrum of 1,1-Diethoxy-3,3-bis(trifluoromethyl)allene. The Effect of Trifluoromethyl Groups on Cumulative SystemsThe He(I) photoelectron(PE) spectra of 1,1-diethoxy-4,4,4-trifluoro-3-(trifluoromethyl)-1,2-butadiene [1,1-diethoxy-3,3-bis(trifluoromethyl)allene] (1), tetraethoxyallene (3), and tetrakis-(trifluoromethyl)allene (5) have been recorded. A comparison between the PE spectra of 1, 3, and 5 shows that the first band of 1 (8.93 eV) is due to an ionization from the diethoxyethylene fragment and the second band of 1 (11.0 eV) is due to ionization from the bis(trifluoromethyl)-ethylene fragment. The effect of CF3 groups has also been discussed by comparing the PE spectra of bis(trifluoromethyl)ketene (6) and bis(trifluoromethyl)thioketene (7) with the parent compounds. The interpretation is aided by comparing the measured ionization potentials with orbital energies derived from a MINDO/3 or MNDO calculation.
    Notes: Die He(I)-Photoelektronen(PE)-Spektren von 1,1-Diethoxy-4,4,4-trifluor-3-(trifluormethyl)-1,2-butadien [1,1-Diethoxy-3,3-bis(trifluormethyl)allen] (1), Tetraethoxyallen (3) und Tetrakis-(trifluormethyl)allen (5) wurden gemessen. Der Vergleich zwischen den PE-Spektren von 1, 3 und 5 zeigt, daß das 1. Ionisationspotential von 1 (8.93 eV) der Ionisation aus dem Diethoxyethylen-Fragment, das 2. Ionisationspotential von 1 (11.0 eV) der Ionisation aus dem Bis(trifluormethyl)ethylen-Fragment entspricht. Der Effekt der CF3-Gruppen wird zusätzlich anhand eines Vergleichs der PE-Spektren von Bis(trifluormethyl)keten (6) und Bis(trifluormethyl)thioketen (7) mit den unsubstituierten Verbindungen diskutiert. Die Interpretation erfolgt durch Vergleich zwischen den gemessenen Ionisationspotentialen und berechneten Orbitalenergien nach der MINDO/3-oder MNDO-Methode.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19831160815
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  • 182
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    cis-Dinitrosylmetall-Komplexe des Chroms, Molybdäns und Wolframs mit schwefelhaltigen Chelatliganden (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 2896-2902 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: cis-Dinitrosylmetal Complexes of Chromium, Molybdenum, and Tungsten with Sulfur-Containing Chelating LigandsOctahedral complexes of the type cis-[M(chelate)2(NO)2] (M = Cr, Mo, W) were prepared by the reactions of the solvent-stabilized dihalogenodinitrosylmetal fragments [MX2-(NO)2]solv (MX2 = CrCl2, MoBr2, WBr2; solv = acetone or acetonitrile) with dithio chelating anions (chelate- = (CH3)2AsS2-, (CH3)2PS2-, (CH3O)2PS2-, (CH3)2N—CS2-). The compounds were characterized by their spectra. Additional chromium complexes, cis-[M(chelat)2(NO)2], were obtained using the chelating ligands Y—CS2- (Y = CH3, CH3S, CH3O), (CH3)2N—COS-, CH3-COS- and (CH3)2N—COSe-.
    Notes: Durch Umsetzung der solvensstabilisierten Dihalogenodinitrosylmetall-Fragmente [MX2-(NO)2]solv (MX2 = CrCl2, MoBr2, WBr2; solv = Aceton oder Acetonitril) mit Dithiochelat-Anionen (chelat- = (CH3)2AsS2-, (CH3)2PS2-, (CH3O)2PS2-, (CH3)2N—CS2-) wurden oktaedrische Komplexe des Typs cis-[M(chelat)2(NO)2] (M = Cr, Mo, W) dargestellt und spektroskopisch charakterisiert. Weitere Chrom-Komplexe cis-[Cr(chelat)2(NO)2] wurden mit den Chelatliganden Y—CS2- (Y = CH3, CH3S, CH3O), (CH3)2N—COS-, CH3-COS- und (CH3)2N—COSe- erhalten.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19831160816
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  • 183
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    Das 7,9-Dimethylbicyclo[4.3.1]deca-2,4,8-trien-7-yl-Kation: Ein überbrücktes Dihomotropyliumion (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 2914-2919 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The 7,9-Dimethylbicyclo[4.3.1]deca-2,4,8-trien-7-yl Cation: A Bridged Dihomotropylium IonThe 7,9-dimethylbicyclo[4.3.1]deca-2,4,8-trien-7-yl cation (3) has been generated. Clearly, the two methyl groups disturb but don't suppress the dihomoaromatic delocalization. The question mentioned in the preceding paper1) cannot be answered unequivocally whether two methyl groups in 1,3-position stabilize the allylic cation of the tricyclic ion 1 so strongly that no trihomoaromatic delocalization takes place.
    Notes: Das 7,9-Dimethylbicyclo[4.3.1]deca-2,4,8-trien-7-yl-Kation (3) wird dargestellt. Die beiden Methylgruppen schwächen eindeutig die dihomoaromatische Delokalisierung, unterbinden sie aber nicht. Die in der voranstehenden Arbeit1) gestellte Frage, ob zwei Methylgruppen in 1,3-Anordnung das Allylkation im tricyclischen Ion 1 so stark stabilisieren, daß die trihomoaromatische Delokalisierung unterbunden wird, läßt sich nicht eindeutig beantworten.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19831160818
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    Das 8-Methyl- und 8,10-Dimethyl-tricyclo[5.3.1.04,11]undeca-2,5,9-trien-8-yl-Kation: Ein Beitrag zur Frage der Existenz eines überbrückten Trihomotropyliumions (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 2903-2913 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The 8-Methyl- and 8,10-Dimethyltricyclo[5.3.1.04,ii]undeca-2,5,9-trien-8-yl Cation: A Contribution to the Question of a Bridged Trihomotropylium IonThe methylcyclohexenyl cation 9 is a short lived intermediate. The thermodynamically more stable cyclopentenyl cations 10a and 10b are generated via hydride shift. 10b finally dominates the equilibrium mixture. The dimethylcyclohexenyl cation 16 shows contrary to 9 no hydride shift. The question of a homoaromatic character in 16 has been denied unequivocally due to a comparison of relevant NMR data between 16 and its tetrahydro derivative 17.
    Notes: Das Methylcyclohexenylkation 9 ist eine kurzlebige Zwischenstufe. Es bildet unter Hydriverschiebung die thermodynamisch stabileren Cyclopentenylkationen 10a und 10b, von denen schließlich 10b das Gleichgewichtsgemisch beherrscht. Im Gegensatz zu 9 zeigt das Dimethylcyclohexenylkation 16 keine Hydridverschiebung. Ein NMR-spektroskopischer Vergleich zwischen 16 und seinem Tetrahydroderivat 17 verneint eindeutig die Frage nach einem trihomoaromatischen Charakter von 16.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19831160817
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  • 185
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    Werden beim Zerfall arylsubstituierter Cyclopentadienyl-Kationen pyramidale Strukturen durchlaufen? (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 2931-2935 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Are Pyramidal Structures Involved in the Decomposition of Aryl-substituted Cyclopentadienyl Cations?Tetra- and pentaaryl-substituted cyclopentadienyl cations undergo dissociation to diaryl-substituted acetylenes and substituted cyclopropenylium ions without any significant skeleton isomerization involving pyramidal or polycyclic carbocation structures.
    Notes: Tetra- und pentaarylsubstituierte Cyclopentadienyl-Kationen zeigen nur eine geringe Tendenz, vor ihrem Zerfall zu Diarylacetylen und substituierten Cyclopropenylium-Ionen Gerüstumlagerungen zu pyramidalen oder polycyclischen Kationen einzugehen.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19831160820
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  • 186
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    Untersuchungen zur Umlagerung cyclischer Allyl- und Pentadienyl-Anionen (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 2958-2971 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Investigation of Rearrangement Reactions of Cyclic Allyl and Pentadienyl AnionsBicyclo[3.1.0]hexenyl anion (1) and bicyclo[3.2.0]heptenyl anion (2) rearrange in THF to monocyclic pentadienyl anions, whereas bicyclo[3.3.0]octenyl anion 3 is stable under the reaction conditions. 3 in contrary is formed by the known electrocyclic ring closure of cyclooctadienyl anion 7. Rearrangements of cyclopentenyl anion and pentadienyl anion are not detected. Cyclic allyl anions are alkylated by ethene, formed by cleavage of THF with base or independently added. 6,6-Dimethylcyclohexadienyl anion undergoes slow fragmentation to toluene at room temperature.
    Notes: Bicyclo[3.1.0]hexenyl-Anion (1) und Bicyclo[3.2.0]heptenyl-Anion (2) lagern sich in THF in die monocyclischen Pentadienyl-Anionen um, während für Bicyclo[3.3.0]octenyl-Anion (3) unter den Reaktionsbedingungen keine Ringöffnung beobachtet wird. Statt dessen geht das Cycloocta-dienyl-Anion 7 den bekannten Ringschluß zu 3 ein. Umlagerungsreaktionen für das Cyclopentenyl-Anion und das offenkettige Pentadienyl-Anion treten nicht ein. Cyclische Allylanionen lassen sich mit Ethen, entstanden aus der Spaltung von THF mit Base oder unabhängig zugeführt, alkylieren. Das 6,6-Dimethylcyclohexadienyl-Anion fragmentiert bei Raumtemperatur langsam zu Toluol.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19831160822
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    Reaktionen der Methylencyclopropane, VII. Nickel(0)-katalysierte Cycloadditionen von Methylencyclopropanen mit Acrylsäure-alkylestern (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 2920-2930 
    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 Methylenecyclopropanes, VII. Nickel(0)-catalysed Cycloadditions of Methylenecyclopropanes with Alkyl AcrylatesCycloaddition reactions of methylenecyclopropane (1) and of the ring-methylated methylene-cyclopropanes 5, 9 and 12 with alkyl acrylates are performed at nickel(0) catalysts, such as bis(1,5-cyclooctadiene)nickel unter mild conditions (0-50°C). Depending on the degree of methylation of the three-membered ring, 1 and 5 give only alkyl 3-methylenecyclopentane-carboxylates (4 and 6), whereas 9 leads to a mixture of the methylenecyclopentane derivative 10 and the alkyl spiro[2.3]hexanecarboxylate 11, and 12 react to form only the spiro[2.3]hexane derivative 13. With 12 isomerisation to 2,3,3-trimethyl-1,4-pentadiene (15) also takes place. In the case of 9 the ratio of methylenecyclopentane to spiro[2.3]hexanecarboxylate can be influenced by the size of alkyl groups. - In the Ni0-catalysed reactions of 1 with substituted acrylates (methyl crotonate or diethyl maleate) codimerisation to 16 and 17 competes with cyclodimerisation to 2 and 3.
    Notes: An Nickel(0)-Katalysatoren, bevorzugt Bis(1,5-cyclooctadien)nickel, gelingen Cycloadditionen von Methylencyclopropan (1) und dessen am Ring methylierten Derivaten 5, 9 und 12 mit Acrylsäure-alkylestern unter milden Bedingungen (0-50°C). In Abhängigkeit von dem Methylierungsgrad des Dreirings entstehen aus 1 und 5 nur 3-Methylencyclopentancarbonsäure-alkylester (4 bzw. 6), aus 9 Gemische dieser Methylencyclopentan-Derivate (10) mit einem Spiro[2.3]hexancarbonsäure-alkylester (11) oder aus 12 nur das Spiro[2.3]hexanderivat 13. Mit 12 tritt auch Isomerisierung zu 2,3,3-Trimethyl-1,4-pentadien (15) ein, Bei 9 kann das Methylencyclopentan-/Spiro[2.3]-hexancarbonsäureester-Verhältnis durch die Größe des Alkylrestes im Acryl beeinflußt werden. - Dagegen konkurrieren bei den Ni0-katalysierten Reaktionen von 1 mit substituierten Acrylsäureestern (Crotonsäure-methylester, Maleinsäure-diethylester) Cyclodimerisierung zu 2 und 3 mit der Codimerisierung zu 16 und 17.
    Additional Material: 3 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19831160819
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    Reaktionen mit Aziridinen, 29. N-Acylierte bzw. N-sulfonierte 2-Aminoethylphosphonsäureester durch basenkatalysierte Amidoethylierung von Phosphorigsäurediestern mit aktivierten Aziridinen (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 2936-2957 
    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 Aziridines (Aziranes), 29. N-Acylated or N-Sulfonated Esters of 2-Aminoethylphosphonic Acid by Means of Base Catalyzed Amidoethylation of Diesters of Phosphoric Acid with Activated AziridinesThe sodium salts 2 of diesters of phosphoric acid 1 are amidoethylated at phosphorus with N-acylaziridines 3 or N-sulfonylaziridines 13 under proper reaction conditions at room temperature. In this manner a broad variation of N-acylated or N-sulfonated esters of 2-aminoethylphosphonic acids (5a-u, 15a-i) are obtained, mostly in good yields. 2-Methylated 2-aminoethyl-phosphonic esters are formed selectively in two cases by reaction of 2-methylated activated aziridines.
    Notes: In Form ihrer Natriumsalze 2 lassen sich Phosphorigsäurediester 1 bei Raumtemperatur unter geeigneten Bedingungen mit N-Acylaziridinen 3 oder N-Sulfonylaziridinen 13 am Phosphoratom amidoethylieren. So werden N-acylierte oder N-sulfonierte 2-Aminoethylphosphonsäureester (5a-u, 15a-i) in großer Variationsbreite mit meist guten Ausbeuten erhalten. Ringmethylierte Aziridine führen dabei in zwei Fällen selektiv zu 2-methylierten 2-Aminoethylphosphonsäureestern.
    Additional Material: 8 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19831160821
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  • 189
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    The electronic structure of phosphorus cages with the nortricyclane skeleton. - Model calculations and photoelectron spectroscopic investigations (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 2972-2982 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Die Elektronenstruktur von Phosphor-Verbindungen mit Nortricyclan-Struktur. - Modell-Rechnungen und PhotoelektronenspektrenDie unterschiedliche Reaktivität der Phosphor-Verbindungen P4[Si(CH3)2]3 (1) and P7(CH3)3 (2) wird anhand eines einfachen MO-Schemas diskutiert. Das MO-Schema basiert auf semiempirischen Rechnungen (MINDO/3, MNDO) und auf He(1)-photoelektronenspektroskopischen Untersuchungen an 1 und 2. Die Elektronenstruktur ähnlich gebauter Käfigverbindungen mit Nortricyclangerüst wie P73-, P4S3 und P7[Si(CH3)3]3 wird mit 1 und 2 verglichen.
    Notes: The different reactivity of P4[Si(CH3)2]3 (1) and P7(CH3)3 (2) is discussed in terms of a simple MO scheme. This scheme is based on semiempirical calculations (MINDO/3, MNDO) and on He(1) photoelectron spectroscopic investigations on 1 and 2. The electronic structure of similar cage compounds with the nortricyclane skeleton like P73-, P4S3, and P7[Si(CH3)3]3 is compared with 1 and 2.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19831160823
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  • 190
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    cis,trans,cis- and trans,trans,trans-1,2,3,4-Tetravinylcyclobutane - preparation and some spectroscopic properties (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 2983-2993 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: cis,trans,cis- und trans,trans,trans-l,2,3,4-Tetravinylcyclobutan - Darstellung und einige spektroskopische EigenschaftenDie Titel-Verbindungen 1 und 2 werden mit Hilfe von bekannten Reaktionsfolgen dargestellt. Die He(1) PE-Spektren von 1 und 2 zeigen eine starke Wechselwirkung (β = -1.9 eV) zwischen den Vinylgruppen und dem Vierring. Die räumliche Wechselwirkung zwischen den Vinylgruppen ist nicht meßbar.
    Notes: The title compounds 1 and 2 are prepared using standard procedures. The He(1) PE spectra of 1 and 2 show strong interaction (β = -1.9eV) between vinyl groups and the four-membered ring. The through space interaction between the vinyl groups is found to be minute.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19831160824
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  • 191
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    Über ein Diazadiboretidin als 4-Elektronen-Donator gegenüber Chrom und Wolfram (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 2994-2999 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: On a Diazadiboretidine as Four-Electron Donor against Chromium and TungstenThe iminoborane Bu—B = N-tBu (1) is dimerized to the diazadiboretidine 2 by the catalytic action to tert-butyl isonitrile, being trimerized to the borazine 3 without a catalyst. The coordination compounds η4-[BuBN(tBu)]2 · M(CO)4 (4a, b) are formed from (OC)5M(THF) (M = Cr, W) and either 1 and 2. The chromium atom in 4a is coordinated by four CO groups and the two nitrogen atoms of a non-planar molecule 2 at the vertices and by the two boron atoms of 2 above two adjoining faces of a distorted octahedron.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19831160825
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  • 192
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    Masthead (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983) 
    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.19831160901
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  • 193
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    Platin(II)-Komplexe von vinylogen Aminoisocyaniden (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 3205-3211 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Platinum(II) Complexes of Vinylogous Amino IsocyanidesIsocyanide platinum(II) complexes trans-[(Ph3P)2LPtCl]+Cl- (2) (L = vinylogous aminoisonitrile are formed from cis-(Ph3P)2PtCl2 and L; the cations of 2 have been isolated as PF6- salts (3). At higher temperatures the salts 2 give the neutral complexes cis-(Ph3P)LPtCl2 (4) and PPh3. Treatment of 4 with amines HNR2R3 affords the diaminocarbene complexes cis-[(Ph3P)[(R1R3N)C]PtCl(amine)]+Cl- (isolated as PF6- salts 5) which on heating give the compounds cis-(Ph3P)[R1HN)(R2R3 N)C]PtCl2 (7).
    Notes: Isocyanid-Platin(II)-Komplexe trans-[Ph3P)2LPtCl]+Cl- (2) (L = vinyloges Aminoisonitril entstehen aus cis-Ph3P)2PtCl2 und L; sie werden als stabile PF6--Salze (3) isoliert. Die Verbindungen 2 spalten beim Erhitzen Ph3P ab unter Bildung der neutralen Komplexe cis-(Ph3P)LPtCl2 (4), die sich mit Aminen HNR2R3 zu den Diaminocarben-Komplexen cis-(Ph3P)[R1HN)(R2R3 N)C]PtCl(amine)+Cl2 (7) umsetzen, wobei als Zwischenstufen ionische Verbindungen [(Ph3P)[R1HN)(R2R3N)C]PtCl(amin)] +PF6- (5) gefaßt wurden.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19831160918
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  • 194
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    Über Metallalkyl- und -aryl-Verbindungen, XXX. Darstellung und Kristallstruktur von Bis[μ-phenylethinyl-(N,N,N′,N′-tetramethyl-1,3-propandiamin) lithium], (PhC≡CLi·tmpda)2, eine dimere Verbindung mit Phenylethinyl-Brücken (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 3212-3215 
    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, XXX. Preparation and Crystal Structure of Bis[μ-phenylethynyl-(N,N,N′,N′-tetramethyl-1,3-propanediamine)lithium], (PhC≡CLi·tmpda)2, a Dimeric Compound with Phenylethynyl BridgesThe title compound has been prepared from n-butyllithium, phenylacetylene and N,N,N′,N′-tetramethyl-1,3-propanediamine (tmpda) and its structure determined by X-ray diffraction methods. It represents a first example containing phenylethynyl bridges between alkali metal atoms and is isostructural to the phenyl compounds (PhLi·tmeda)2.
    Notes: Die Titelverbindung wurde aus n-Butyllithium, Phenylacetylen und N,N,N′,N′-Tetramethyl-1,3-propandiamin (tmpda) dargestellt und ihre Struktur röntgenographisch bestimmt. Sie stellt ein erstes Beispiel von Phenylethinyl-Brücken zwischen Alkalimetall-Atomen dar und ist isostrukturell zur Phenylverbindung (PhLi·tmeda)2.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19831160919
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  • 195
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    Zur Umsetzung von 2-(Aminomethylen)cyclohexanon-Derivaten mit Dichlorchinonen (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 152-158 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reaction of 2-(Aminomethylene)cyclohexanone Derivatives with DichloroquinonesReaction of dichloro-p-benzoquinones 1 with 2-[(arylamino)methylene]cyclohexanone derivatives 2 yield dibenzofuranone derivatives 4. The structure is proven spectroscopically and by oxidation to 6, which is hydrolysed to 7. The course of the reaction via the intermediate 10 can be proved by its isolation and reaction to 4a.
    Notes: Durch Umsetzung von Dichlor-p-benzochinonen 1 mit 2-[(Arylamino)methylen]cyclohexanon-Derivaten 2 werden die Dibenzofuran-Abkömmlinge 4 erhalten. Ihre Struktur wird spektroskopisch belegt und durch Oxidation zu 6 sowie anschließende Hydrolyse zu 7 chemisch bewiesen. Der Verlauf der Reaktion über das Zwischenprodukt 10 kann durch dessen Isolierung und Umsetzung zu 4a bewiesen werden.
    Additional Material: 7 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19831160118
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  • 196
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    Reaktionen mit Radikalanionen, I. Synthese offenkettiger und cyclischer, silylierter 1,2-Ethendiamine (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 136-145 
    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 Radical Anions, I. Synthesis of Acyclic and Cyclic Silylated 1,2-EthenediaminesReactions of radical anions obtained by the reduction of glyoxal diimines RN=CH—CH=NR 3 (3a: R = tert-butyl; 3b: R = 2,6-xylyl) with chlorotrimethylsilane, dichlorodimethylsilane, and dichloromethylsilane afford acyclic N-mono and N,N′-disilylated ene-diamines 6, 8, 9, and cyclic diazasilacyclopentenes 10, 11, 13, respectively. C-Silylation is a minor side-reaction. 13C NMR, IR, and PE data are consistent with a non-planar E-configuration for 8 and Z-configuration for 6. In agreement with MS data and the very low 1. ionisation potentials, the planar heterocycles 10 and 13 on oxidation yield stable, delocalized radical cations, which are characterized ESR-spectroscopically.
    Notes: Durch Reduktion der Glyoxaldiimine RN=CH—CH=NR 3 (3a: R = tert-Butyl; 3b: R = 2,6-Xylyl) erhältliche Radikalanionen reagieren mit Chlortrimethylsilan, Dichlordimethylsilan und Dichlormethylsilan zu offenkettigen N-mono- bzw. N,N′-disilylierten En-diaminen 6, 8, 9 bzw. zu cyclischen Diazasilacyclopentenen 10, 11, 13. C-Silylierung wird nur als Nebenreaktion beobachtet. 13C-NMR-, IR- und PE-Daten belegen eine nicht-planare E-Konfiguration für 8 und Z-Konfiguration für 6. Die planaren Heterocyclen 10 und 13 bilden in Übereinstimmung mit den MS-Daten und der geringen 1. Ionisierungsenergie stabile, delokalisierte Radikalkationen, die ESR-spektroskopisch charakterisiert werden.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19831160116
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  • 197
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    Alkylruthenium(II)-Verbindungen und ihre β-H-Eliminierung zu (η2-Alken)hydridoruthenium-Komplexen (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 159-175 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Alkylruthenium(II) Compounds and their β-H-Elimination into (η-2Alkene)hydridoruthenium ComplexesReaction of Cp(PPh3)2RuCl (1) with primary alkylmagnesium halides (alkyl = Et, Pr, n-Bu, i-Bu) leads to the corresponding alkylruthenium complexes 4-7. Above 50°C 4-7 lose a PPh3 molecule and form by Ru-β-H-elimination the (η2-alkene)hydridoruthenium complexes 9-12. With R = isobutyl the intermediately formed, coordinatively unsaturated Cp(PPh3)Ru—R complex can be stabilized by complexation with ethylene (50 bar) as (η2-ethylene)isobutylruthenium complex 15. Mechanistic investigations of the [2-D3]ethyl complex 16 indicate that the Ru-β-H-elimination is reversible. - Rotation of the η2-alkene ligand in 9-12 leads to temperaturedependent 1H NMR spectra. The 31P chemical shifts of 1, 2, 4-7 and 9-12, respectively, are characteristic for the corresponding type of complexes.
    Notes: Durch Umsetzung von Cp(PPh3)2RuCl (1) mit prim. Alkylmagnesiumhalogeniden (Alkyl = Et, Pr, n-Bu, i-Bu) werden die entsprechenden Alkylruthenium-Komplexe 4-7 erhalten. Ab ca. 50°C spalten 4-7 ein PPh3 ab und bilden durch Ru-β-H-Eliminierung die (η2-Alken)hydridoruthenium-Komplexe 9-12. Das intermediär entstehende, koordinativ ungesättigte Cp (PPh3)Ru—R wurde bei R = Isobutyl mit Ethylen (50 bar) als (η2-Ethylen)isobutylruthenium-Komplex 15 abgefangen. Aus mechanistischen Untersuchungen mit dem [2-D3]Ethylkomplex 16 folgt die Reversibilität der Ru-β-H-Eliminierung. - Die Rotation des η2-Alken-Liganden in 9-12 bedingt temperaturabhängige 1H-NMR-Spektren. Die 31P-chemischen Verschiebungen sind bei 1, 2, 4-7 bzw. 9-12 jeweils charakteristisch für den Verbindungstyp.
    Additional Material: 8 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19831160119
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  • 198
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    Alkenylruthenium(II)-Komplexe (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 176-185 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Alkenylruthenium(II) ComplexesThe Cp(PPh3)2Ru—[CH2]nCR=CH2 complexes 2-4 (n = 0.2. R = H; n = 3, R = CH3) are prepared by treatment of the chloride 1 with the appropriate organomagnesium halides. The vinyl complex 2 eliminates a PPh3 ligand above 100°C and reacts with ethylene (20-30 bar) by insertion into the Ru - vinyl bond to give the (η3-1-methylallyl)ruthenium complex 6a. The 3- and 4-alkenyl compounds 3 and 4 isomerize at 80-100°C after dissociation of one PPh3 via an (η2-alkadiene)hydridoruthenium intermediate, e.g. 7, to form the η3-allyl complexes 6, 8, and 9, respectively. The stable (η1,η2-4-alkenyl)ruthenium compounds 10-12 are formed if isomerization by β-H-elimination is prevented by E-configuration of Ru and β-H in a conformatively inflexible cyclopropyl system. The 31P chemical shifts of 2-4 and the (η1-allyl)ruthenium complexes, of 10-12, and of the η3-allyl complexes 6a, 8, 9, 13a are characteristic for the corresponding type of compounds.
    Notes: Die Cp(PPh3)2Ru—[CH2] nCR=CH2-Komplexe 2-4 (n = 0, 2, R = H; n = 3, R = CH3) werden durch Umsetzung des Chlorids 1 mit den entsprechenden Organomagnesiumhalogeniden dargestellt. Die Vinylverbindung 2 spaltet oberhalb 100°C einen PPh3-Liganden ab und reagiert mit Ethylen (20-30 bar) unter Insertion in die Ru - Vinyl-Bindung zum (η3-1-Methylallyl)ruthenium-Komplex 6a. Die 3- und 4-Alkenylverbindungen 3 und 4 isomerisieren bei 80-100°C nach Abspaltung eines PPh3 über (η2-Alkadien)hydridoruthenium-Zwischenstufen, z. B. 7, zu η3-Allyl-Komplexen 6 bzw. 8 und 9. Stabile (η1,η2-4-Alkenyl)ruthenium-Verbindungen 10-12 werden erhalten, wenn die Isomerisierung über β-H-Eliminierung durch E-Konfiguration von Ru und β-H in einem konformativ starren Cyclopropyl-System verhindert ist. Die 31P-chemischen Verschiebungen von 2-4 und den (η1-Allyl)ruthenium-Komplexen, von 10-12 bzw. den η3-Allylverbindungen 6a, 8, 9 und 13a sind jeweils charakteristisch für den Verbindungstyp.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19831160120
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  • 199
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    Reaktionen heterocyclischer Oniumsalze mit elektronenreichen Mehrfachbindungssystemen (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 186-196 
    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 Heterocyclic Onium Salts with Electron-rich Multiple Bond SystemsThe N-phenylquinolinium salt 4 reacts with ketene diethyl acetal (5) by angular anellation to give 6. On the contrary, with ynamine 2 an open-chain 1:2 adduct (14) with cross-conjugated cyanine structure is obtained which is proved by X-ray analysis. With 1,2,4-triazolium salts and 2 [3+ + 2] cycloaddition-cycloreversion as well as [4+ + 2] cycloaddition are observed. With tetrazolium salt 28 and 2 deprotonation and cycloelimination of N2 occurs. The 5-aryl-substituted tetrazolium salt 32 suffers dealkylation with 2.
    Notes: Das N-Phenylchinoliniumsalz 4 reagiert mit Keten-diethylacetal (5) unter angularer Anellierung zu 6. Mit dem Inamin 2 hingegen gibt 4 ein offenkettiges 1 : 2-Addukt (14) mit kreuzkonjugierter Cyaninstruktur, die durch Röntgenstrukturanalyse bewiesen ist. Bei 1,2,4-Triazoliumsalzen werden mit 2 sowohl [3+ + 2]-Cycloaddition/Cycloreversion als auch [4+ + 2]-Cycloaddition beobachtet. Das Tetrazoliumsalz 28 wird durch 2 deprotoniert und cycloeliminiert N2. Das 5-arylsubstituierte Tetrazoliumsalz 32 wird durch 2 desalkyliert.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19831160121
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  • 200
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    Übergangsmetall-Schwefelylid-Komplexe, XIV. π-Komplexe von 1-Alkyl-3,5-diphenyl-λ4-thiabenzolen mit Dicarbonylnitrosylchrom (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 197-206 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Transition Metal Sulfur Ylide Complexes, XIV. π-Complexes of 1-Alkyl-3,5-diphenyl-λ4-thiabenzenes with Dicarbonylnitrosylchromium1-Alkyl-3,5-diphenyl-λ4-thiabenzene chromium complexes 2a-f are oxidized by NOPF6 in CH2Cl2 at -70°C, yielding the cationic dicarbonylnitrosyl complexes 3a-f. The temperature dependence of the 1H NMR spectra of 3a-f is consistent with a hindered rotation of the ring ligands. The X-ray structure analysis of 3b shows that the molecule in the solid state possesses no local Cs-symmetry.
    Notes: Die 1-Alkyl-3,5-diphenyl-λ4-thiabenzol-Chromkomplexe 2a-f werden durch NOPF6 in CH2Cl2 bei -70°C unter Bildung der kationischen Dicarbonylnitrosyl-Spezies 3a-f oxidiert. Die temperaturabhängigen 1H-NMR-Spektren dieser Komplexe deuten auf gehinderte Rotation der Ringe um das (CO)2(NO)Cr+-Fragment hin. Die Röntgenstrukturanalyse von 3b zeigt, daß das Molekül im Kristall keine lokale Cs-Symmetrie mehr besitzt.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19831160122
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