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  • Electronic Resource  (75)
  • 1985-1989  (75)
  • Chemistry  (75)
  • 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
    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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  • 3
    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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  • 4
    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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  • 5
    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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  • 6
    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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  • 7
    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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  • 8
    Electronic Resource
    Electronic Resource
    Durch LiF-Eliminierung zu (SiNSiO)-Vierringen - Kristallstruktur eines achtgliedrigen (FLiNSi)-Ringes (1987)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 120 (1987), S. 611-616 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: 1,3-Functional siloxanes [(CMe3)2SiR - O - SiR′2Hal, R=OH, Hal=Cl, R′=CHMe2 (3); R=NH2, Hal=F, R′=CHMe2 (4), R′=CMe3 (5)] are obtained in the reaction of dihalogenosilanes with the lithiated diol 1 and the aminosilanols 2, respectively. The lithium salts of 3 and 4 lose LiHal thermally to give eight-membered (SiO) (6) or (SiNSiO) (7) rings. Substitutions of 4 and 5 with halogenosilanes lead to the formation of the 1-(silylamino)disiloxanes 8 - 14. Compounds 11 and 13 as well as 12 and 14 are sturcutral isomers and are formed by 1,3-silyl group migration of lithiated 4. The intramolecular cyclisation of 8 and 10, which is catalysed by the presence of fluorosilanes, is a direct synthesis of 1-oxa-3-aza-2,4-disilacyclobutanes (15, 16). The lithium derivatives of 9 and 14, 9a and 14a, show no tendency to eliminate LiF. The crystal structure determination shows that 14a is a dimer with planar three-coordinated lithium and nitrogen atoms.
    Notes: 1,3-Funktionelle Siloxane [(CMe3)2SiR - O - SiR′2Hal, R=OH, Hal=Cl, R′=CHMe2 (3); R=NH2, Hal=F, R′=CHMe2 (4), R′=CMe3 (5)] werden durch Reaktion der Dihalogensilane mit lithiiertem Diol 1 und Aminosilanol 2 erhalten. Die Lithiumsalze von 3 und 4 verlieren thermisch LiHal unter Bildung achtgliedriger (SiO)- (6) bzw. (SiNSiO)-Ringe (7). Substitutionen von 4 und 5 mit Halogensilanen führen zur Bildung der 1-(Silylamino)disiloxane 8 - 14. Die Verbindungen 11 und 13 sowie 12 und 14 sind Strukturisomere, die durch 1,3-Silylgruppenwanderung beim lithiierten 4 entstehen. Die durch Anwesenheit von Difluorsilanen katalysierte, intramolekulare Cyclisierung von 8 und 10 stellt eine gezielte Synthese für 1-Oxa-3-aza-2,4-disilacyclobutane (15, 16) dar. Die Lithiumderivate von 9 und 14 - 9a und 14a - zeigen keine Tendenz zur LiF-Eliminierung. Nach der Kristallstrukturanalyse ist 14a ein Dimer mit planaren dreifach koordinierten Lithium- und Stickstoffatomen.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19871200424
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  • 9
    Electronic Resource
    Electronic Resource
    Reaktionen von Übergangsmetallhalogeniden mit Dimethylsulfoximin- Derivaten - Röntgenstrukturanalyse von F5WNS(O)Me2 und F4W[NS(O)Me2]2 (1987)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 120 (1987), S. 1881-1884 
    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 Transition Metal Halides with Derivatives of Dimethylsulfoximine - X-Ray Single Structure Analysis of F5WNS(O)Me2 und F4[NS(O)Me2]2WF6 reacts with Me2S(O)NSiMe3 (1) in a molar ratio 1:1 to give F5WNS(O)Me2 (2), which reacts further with 1 to yield F4W[NS(O)Me2]2 (3). 2 and 3 were characterized i. a. by X-ray crystal structure analyses. In these compounds there is evidence of multiple bonding between N and W. Reaction of 3 with Me2S(O)NLi leads to substitution of a further fluorine atom with formation of F3W[NS(O)Me2]3 (4). Cl4W[NS(O)Me2]2 (5) and Cl4MoNS(O)Me2 · CH3CN (6) are formed by the reaction of WCl6 and MoCl5 with 1.
    Notes: WF6 reagiert mit Me2S(O)NSiMe3 (1) im Molverhältnis 1:1 zu F5WNS(O)Me2, das mit 1 zu F4W[NS(O)Me2]2 (3) umgesetzt wird 2 und 3 werden u. a. durch Röntgenstrukturanalysen charakterisiert. In diesen Verbindungen besteht ein Mehrfachbindungsteil zwischen N und W. Mit Me2S(O)NLi reagiert 3 unter Substitution eines weiteren Fluoratoms zu F3W[NS(O)Me2]3 (4). Cl4W[NS(O)Me2]2 (5) und Cl4MoNS(O)Me2 · CH3CN (6) entstehen bei der Umsetzung von WCl6 und MoCl5 mit 1.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19871201117
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  • 10
    Electronic Resource
    Electronic Resource
    Perhalogenierte 1,2,3,5-Dithiadiazolium-Salze und 1,2,3,5-Dithiadiazole (1985)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 3781-3804 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Perhalogenated 1,2,3,5-Dithiadiazolium Salts and 1,2,3,5-DithiadiazolesSyntheses of the perhalogenated 1,2,3,5-dithiadiazolium salts FCN2S2+Cl- (5) (by methathesis from ClCN2S2+Cl- with AgF2), FCN2S2+AsF6- (5a) (from 5 and AgAsF6), CF3CN2S2+Cl (11) (from CF3CN and S3N3Cl3 in liquid SO2 (in this reaction the by-products S5N5+Cl4- (9), S4N4O2 (10), CF3CN3S2Cl2 (11a), and CF3CN4S3+S3N3O4- (12) are isolated, too), and BrCN2S2+Cl- (15) (from 13c and SO2Cl2) are reported. By reduction of XCN2S2+ (Cl, Br)- with Zn in liquid SO2 the corresponding radicals XCN2S2· (13a - d, X = F, Cl, Br, CF3) are formed in high yields. These radicals are diamagnetic in the solid state. From 13b and d and their corresponding chlorides distinct compounds of the composition (XCN2S2)3Cl (16a, b, X = Cl, CF3) are obtained, while in the reaction of 13b with ClCN2S2+SbCl6 only reduction of the anion under formation of (ClCN2S2+)2SbCl52- (17) occurs. Structures of 13d and 16b were determined by X-ray-, of 13d also by electron-diffraction in the vapour phase. In order to understand the observed structures and ESR spectra of 13, model calculations by the MNDO method were performed for the RCN2S2-system and also for possible dimers there of.
    Notes: Synthesen der perhalogenierten 1,2,3,5-Dithiadiazolium-Salze FCN2S2+Cl- (5) (durch Metathese aus ClCN2S2+Cl- mit AgF2), FCN2S2+AsF6- (5a) (aus 5 und AgAsF6), CF3CN2S2+Cl- (11) (aus CF3CN und S3N3Cl3 in fl. SO2 (bei dieser Reaktion werden als Nebenprodukte u.a. S5N5+FeCl4- (9), S4N4O2 (10), CF3CN3S2Cl2 (11a) und CF3CN4S3+S3N3O4- (12) isoliert) und BrCN2S2+Cl- (15) (aus 13c und SO2Cl2) werden mitgeteilt. Durch Reduktion von XCN2S2+(Cl, Br)- mit Zn in fl. SO2 entstehen die entsprechenden Radikale XCN2S2· (13a-d, X = F, Cl, Br, CF3) in hohen Ausbeuten. Diese Radikale sind im festen Zustand diamagnetisch. Durch Umsetzung von 13b und d mit den ihnen zugrunde liegenden Chloriden lassen sich definierte Verbindungen der Zusammensetzung (XCN2S2)3Cl (16a, b, X = Cl, CF3) erhalten. Bei der Umsetzung von ClCN2S2+SbCl6- mit 13b erfolgt dagegen Reduktion des Anions unter Bildung von (ClCN2S2+)2 SbCl52- (17). Die Strukturen von 13d und 16b wurden durch Röntgen-, die von 13d außerdem durch Elektronenbeugung in der Gasphase bestimmt. Zum Verständnis der gefundenen Strukturen und der gemessenen ESR-Spektren von 13 wurden Modellrechnungen nach der MNDO-Methode an dem RCN2S2-System sowie an den möglichen Dimeren von 13 durchgeführt.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19851180930
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