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  • 1
    Electronic Resource
    Electronic Resource
    Conformational Analysis of Didemnins. A multidisciplinary approach by means of X-Ray, NMR, molecular-dynamics, and molecular-mechanics techniques (1989)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 72 (1989), S. 530-555 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We present the application of several homo- and heteronuclear 1D- and 2D-NMR techniques to assign the 1H-NMR chemical shifts of the dominant conformation of didemnin B (2; three different conformations in (D6)DMSO solution in the ratio 8:1:1) and its conformational analysis, as well as the solution conformation of didemnin A (1). The conformations were refined by restrained molecular-dynamics calculations using the GROMOS program and by MOMO, a novel personal-computer-based interactive molecular-graphics and molecular-mechanics package, using experimental distances (via a H…H pseudo potential function) as restraints. The solution structures of 1 and 2 obtained by GROMOS and MOMO calculations were compared with each other and related to the recently solved crystal structure of 2. Focusing on the main conformer, the two kinds of the distance-restrained conformational calculations for 2 yielded a ‘solution structure’ close to the crystal structure. Almost all of the 40 restrained H…H distances coincided (within the estimated standard deviations) with those observed in the crystal structure. One more hydrogen bond was detected in solution involving the lactoyl OH group (disordered in the crystal structure) and the dimethyltyrosine (Me2Tyr5) carbonyl O-atom. The macrocyclic ring system in the modeled solution structure of 1 exhibited a topology close to those of the solution and crystal structures of 2. The main difference between 1 and 2 could be traced back to a significant change in the Ψ angle of the N-methyl-D-leucine (MeLeu7) residue. In 1, the N-methyl moiety of MeLeu7 points inward within the macrocyclic ring toward the 1st and Hip region. We also tested the suitability of structures obtained from NMR data as ‘search fragments’ in the ‘Patterson search approach’ of crystal-structure analysis. It proved possible to resolve the crystal structure of 2 a posteriori with the Patterson search program PATSEE, in this way.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19890720316
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  • 2
    Electronic Resource
    Electronic Resource
    Crystal Structures of Two Modifications of [3,O-didehydro-mebmt1, val2]-cyclosporin and comparison of three different X-ray data sets (1995)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 78 (1995), S. 355-366 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The crystal structure of [3,O-didehydro-MeBmt1, Val2]cyclosporin (PSC-833; 1) was investigated by X-ray analysis. Data were collected from two different crystal modifications. Modification I crystallizes in P3121, a = b = 21.419 (2) Å, c = 32.101 (3) Å with one molecule in the asymmetric unit, modification II in P3221, a = b = 21.313 (2) Å, c = 62.053(3) Å with two molecules per asymmetric unit. This non-immunosuppressive analogue of cyclosporin A adopts a similar backbone conformation to that found in the crystal structure of cyclosporin A and other analogues. Three different data sets of modification I were collected using an Enraf-Nonius-CAD4 diffractometer with CuKα radiation at 20°, a Stoe-Siemens four-circle diffractometer with MoKα radiation at - 120°, and an EMBL image-plate scanner with synchrotron radiation at 12°. The quality of the data sets was evaluated by internal consistency, independent structure solution, and refinement. The structural parameters reported here for modification I are based on the synchrotron data.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19950780208
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  • 3
    Electronic Resource
    Electronic Resource
    Preparation and Some Reactions of 1H-1,4-Benzothiazine Ylides (= 1H-1,4-Benzothioniaazin-4-ide) (1985)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 2216-2225 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of fifteen 1H-1,4-benzothiazine ylides were obtained by alkylation of the corresponding 4H-1,4-benzothiazines 1. Ylides of type 2g-r showed slight [1,2] rearrangements upon thermolysis besides main dealkylation to 1 and olefin production. The ylides of this type underwent redox reactions when treated with hydrazine hydrate alone, giving 3,4-dihydro-2H-1,4-benzothiazines mainly, while ylides of type 2a-f failed to react.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19850680816
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  • 4
    Electronic Resource
    Electronic Resource
    Additionsreaktionen von 1,1-Dicyan-2,2-bis(trifluormethyl)ethen (1986)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 119 (1986), S. 3150-3157 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Addition Reactions of 1,1-Dicyano-2,2-bis(trifluoromethyl)etheneBy the reaction of the title compound (CF3)2C=C(CN)2 with PCl5 the (phosphoranyliden-amino)ethene 1 is obtained. The phosphorane 1 reacts with Me3SiNMe2 to form 2. WCl6 and MoCl5 react with (CF3)2C=C(CN)2 to give the acyclic nitrenes 3 and 4. The X-ray structure analysis of 3a, an acetonitrile adduct of 3, is reported.
    Notes: Die Titelverbindung (CF3)2C=C(CN)2 reagiert mit PCl5 zu dem (Phosphoranylidenamino)-ethen 1. Daraus entsteht 2 durch Reaktion mit Me3SiNMe2. Umsetzungen von (CF3)2C=C(CN)2 mit WCl6 und MoCl5 ergeben die acyclischen Nitrenkomplexe 3 und 4. Von 3a, einem Acetonitriladdukt von 3, wird eine Röntgenstrukturanalyse mitgeteilt.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19861191022
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  • 5
    Electronic Resource
    Electronic Resource
    Carben-analoge Reaktionen der Dehalogenierungsprodukte von Dichlor(diisopropylamino)boran mit Aromaten und 1,2-Dimethoxyethan (1987)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 120 (1987), S. 1437-1439 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Carbene-Analgous Reactions of the Products of Dehalogenation of Dichloro(diisopropylamino)borane with Aromatic Compounds and 1,2-DimethoxyethaneSodium complexes of aromatic compounds in 1,2-dimethoxyethane react with dichloro-diisopropylamino)borane to give compounds formed via carben(oidal) intermediates: From naphthalene 1,2-bis(diisopropylamino)-1,1a,2,8b-tetrahydroborireno[2,3-b][3]benzoborepine (1) is formed. From acenaphthylene 2-(diisopropylamino)-2,3-dihydro-1H-naphtho[1,8-cd]borine (2) and with 1-methylnaphthalene, in addition to 1,2-bis[(diisopropylamino)methoxyboryl]ethyne (3), (diisopropylamino)dimethoxyborane (4) is isolated. 1H-, 11B-, 13C-, 14N-, 15N NMR and MS data are given. For 3 the X-ray structure is reported.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19871200823
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  • 6
    Electronic Resource
    Electronic Resource
    Benzamidinatokomplexe mit Haupt- und Nebengruppen-Elementen - Strukturen von PhC(NSiMe3)2TiCl2 und PhC(NSiMe3)2MoO2 (1988)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 121 (1988), S. 1403-1406 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Benzamidinato Complexes of Main Group and Transition Metals - Crystal Structures of PhC(NSiMe3)2TiCl2 and PhC3)2MoO2PhC(NSiMe3)2Li (3b) reacts with SiCl4, SnCl4, Me2SnCl2, Ph2SnCl2, TiCl4, ZrCl4, MoO2Cl2, and WO2Cl2 with formation of LiCl to yield the new amidinato complexes 4a-f, 5a and 5b. The X-ray structure analyses of 4e and 5a are reported.
    Notes: PhC(NSiMe3)2Li (3b) reagiert mit SiCl4, SnCl4, Me2SnCl2, Ph2SnCl2, TiCl4, ZrCl4, MoO2Cl2 und WO2Cl2 unter Bildung von LiCl zu den Amidinatokomplexen 4a-f, 5a und 5b. Von 4e und 5a wird die Röntgenstrukturanalyse mitgeteilt.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19881210807
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  • 7
    Electronic Resource
    Electronic Resource
    The Molecular and Crystal Structure of the Glycopeptide A-40926 Aglycone (1996)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 79 (1996), S. 1916-1924 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The crystal structure of a glycopeptide antibiotic A-40926 aglycone was investigated by X-ray analysis at -120°. A-40926 crystallises in the orthorhombic space group P212121 with two monomers in the asymmetric unit, a = 21.774(4), b = 28.603(7), c = 29.757(4) Å. ‘Conventional’ direct methods approach failed to solve the structure, but a novel iterative real/reciprocal space procedure was successful. Refinement against 11248 F2 data led to R1 = 13.3% for 6770 F 〉 4σ (F). The two monomers of A-40926 have similar conformations and are bound by antiparallel H-bonds to form a ‘chain’ structure of connecting dimers. The antibiotic molecule possesses a ‘binding pocket’ for the C-terminal carboxy group of the cell-wall protein, which is consisten with suggestions based on NMR data and the recently reported crystal structure of ureido-balhimycin. In A-40926 the monomers are polymerically linked by H-bonds, quite unlike the tight dimer formation observed in ureido-balhimycin.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19960790714
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  • 8
    Electronic Resource
    Electronic Resource
    Crystal Structure and Packing of Isocyclosporin A (1996)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 79 (1996), S. 1635-1642 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The crystal structure of isocyclosporin A (1), a rearrangement product of the immunosuppressant drug cyclosporin A, has been determined at 193 (2) K. Crystals are orthorhombic with cell dimensions a = 26.684 (7), b = 26.936 (3) Å, c = 28.549 (7) Å, space group C2221. The structure was solved by direct methods and refined by full-matrix least-squares methods to a conventional R value of 0.110. In contrast to the structure of cyclosprin A in solution and in the crystal, isocyclosporin A (1) has no regular secondary structural elements. The backbone adopts an open, irregular conformation with cis amide bonds between residue 2 and 3, and 3 and 4, respectively. All the other amide bonds and the ester linkage are trans. Contrary to crystal structures of cyclosporin derivatives, this crystal structure is stabilized by two transannular and four intermolecular H-bonds.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19960790614
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  • 9
    Electronic Resource
    Electronic Resource
    Darstellung und Struktur neuer sechsgliedriger Metallaheterocyclen - Insertion von Platin in Selen-Stickstoff- und Schwefel-Stickstoff-Bindungen (1986)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 119 (1986), S. 366-373 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Preparation and Structure of New Six-membered Metallaheterocycles - Insertion of Platinum in Selenium-Nitrogen and Sulfur-Nitrogen BondsThe reaction of 1,2,5-selenadiazoles 2 and 4 and the bicycle 6 with (η2-ethene)bis(triphenylphosphane)platinum(0) leads to the cyclic coordination compounds (Ph3P)2PtSeN2(CR)2 (R = CN, 3; R = OCH2CF3, 5) and the bicycle (Ph3P)2PtC4Cl2N4S3 (7). The structure of 3 was determined by an X-ray structure analysis.
    Notes: Die Reaktion der 1,2,5-Selenadiazole 2 und 4 sowie des Bicyclus 6 mit (η2-Ethen)bis(triphenylphosphan)platin(0) führt zu den cyclischen Koordinationsverbindungen (Ph3P)2-PtSeN2(CR)2 (R = CN, 3; R = OCH2CF3, 5) und dem Bicyclus (Ph3P)2PtC4Cl2N4S3 (7). Von 3 wurde eine Röntgenstrukturanalyse angefertigt, die das Vorliegen eines sechsgliedrigen Ringes bestätigt.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19861190131
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  • 10
    Electronic Resource
    Electronic Resource
    Kristallstruktur von 2,4,4-Trifluor-1,3-dithietan-2-ylium-hexafluoroarsenat (1985)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 5006-5008 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Crystal Structure of 2,4,4-Trifluoro-1,3-dithietan-2-ylium HexafluoroarsenateCrystals of [F2CS2CF]⊕ [AsF6]⊖ are orthorhombic, space group Pmmn, with a = 764.9(1), b = 831.7(1), c = 690.3(1) pm. The cation possesses mm symmetry and does not show any short intermolecular interactions. The C—F and C—S bonds to the cationic carbon are significantly shorter than the other C—F and C—S bonds. The anion exhibits twofold disorder.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19851181231
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