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  • 1
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Substituted dihydroxystilbenes 2 are suitable starting materials for the synthesis of photochromic systems derived from 3/4. Attempts to couple the naphthones 8a-8e by the McMurry reaction with TiCl3/LiAlH4 yielded mainly reduction products such as 8f, g or 9. However, the furofuran 3b was isolated when using the zinc-copper couple for reduction. The helicene 11 was formed as an unexpected by-product in the McMurry reaction of the pivaloylnaphthalene 8d.
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  • 2
    ISSN: 0947-3440
    Keywords: Asymmetric induction ; Diastereoselectivity ; 1,3-Diol ; Lithiation, reductive ; Rearrangement, retro-Brook ; Silane, α-chiral ; Silane, crotyl- ; Silane, γ-hydroxy- ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Treatment of alcohols cis-22, cis-23, and trans-23 with PPh3/ Ph2S2 provided three mixtures of isomers of α, γ-disubstituted allyl phenyl sulfides. They consisted of diastereomers and -except starting from trans-23-of regioisomers. Each mixture was lithiated reductively by lithium naphthalenide at -78°C in THF. α, γ-Disubstituted allyllithium compounds resulted which underwent retro-[1,4]-Brook rearrangements within 30-90 min. A high degree of stereocontrol by 1,3-asymmetric induction was observed in the rearrangement starting from a 5:1 mixture of the tBuPh2Si-containing sulfide regioisomers cis-25 and iso-25 (each regioisomer consisting of more than one diastereomer): The α-chiral crotylsilane anti, trans-26 was formed as a racemic mixture with ds = 93:7:0:0 in preference to isomer syn,trans-26 which possesses the opposite configuration at the silicon-bearing stereocenter and in preference to the corresponding cis isomers (Scheme 5). The rearrangements of the two other sulfide mixtures were much less stereoselective and exhibited ds = 49:44:4:3 starting from the two tBuPh2Si-containing diastereomers of the isomeric sulfide trans-25 (Scheme 5) and ds = 59:41 starting from the 3.5:1 mixture of the MePh2Si-containing sulfide regioisomers cis-24 and iso-24 (each regioisomer consisting of more than one diastereomer; Scheme 9). The stereostructures of the rearrangement products were determined by chemical correlations, NMR analogies, and a crystal structure analysis of 27. It was proven that the stereochemical outcome of the retro-[1,4]-Brook rearrangements of the MePh2Si-containing 3.5:1 mixture of sulfides cis-24/iso-24 is kinetically rather than thermodynamically controlled (Scheme 10). Mechanistic aspects are discussed in Schemes 11-13.
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  • 3
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Topography of Cyclodextrin Inclusion Complexes, VII* X-Ray Analysis of α-Cyclodextrin. Krypton Pentahydrate. On the Inclusion Mechanism of the Model EnzymeWhen crystallized from water under krypton pressures of 43 PSI (A) and 200 PSI(B), α-cyclodextrin (α-CD) yields inclusion compounds of composition α-CD·(0.78 H2O, 0.48 Kr)·5H2O (A) and α-CD·(0.28 H2O, 0.74 Kr)·5H2O (B). Both the adducts are isomorphous, space group P212121. The structures were determined from about 3900 X-ray data and refined to an R-factor of 8.8%. Although Kr has nearly the same van der Waals diameter as H2O (4Å), the structures of the Kr and of the recently determined α-CD·2H2O adduct are different. In the latter, the 5.0 Å wide cavity of α-CD is diminished by rotation of two glucoses, rendering the α-CD conformation strained. in the almost hexagonal Kr-adduct, all six glucoses are approximately equivalent, the cavity is 5 Å in diameter and the Kr is statistically disordered over five positions. It is concluded that α-CD adducts are stabilized through release of conformation- and hydrogen bonding energy when the “empty” α-CD·2H2O adduct transforms into any other adduct. This mechanism explains why so many different guest molecules are enclosed and bears some relation to enzyme-substrate interactions.
    Notes: α-Cyclodextrin (α-CD) liefert aus Wasser in Gegenwart von Krypton bei 3 und 14 atü kristalline Einschlußverbindungen der Zusammensetzung α-CD·(0.78H2O, 0.48 Kr)·5 H2O (A) und α CD·(0.28 H2O, 0.74 Kr)·5H2O (B). Beide sind isomorph, Raumgruppe P212121. Die Strukturen wurden aus etwa 3900 Röntgenreflexen gelöst und bis zu einem R-Faktor von 8.8% verfeinert. Obwohl Kr mit 4 Å van der Waals- Durchmesser etwa ebenso groß ist wie H2O3, sind die Strukturen der Kr-Addukte von der des reinen αCD·2H2O-Adduktes verschieden. Der 5.0 Å große Hohlraum im α-CD wird im H2O-Addukt durch Rotation zweier gegenüberliegender Glucosen zusammengezogen und dadurch gespannt. Im beinahe hexagonalen Kr-Addukt sind alle sechs Glucosen annähernd gleichwertig und das Kr besetzt statistisch fünf verschiedene Lagen, um den 5.0 Å weiten Innenraum auszufüllen. Es wird gefolgert, daß beim Austausch des Wassers gegen Gastmoleküle frei werdende Konformations- und Wasserstoffbrückenenergie die Addukte stabilisiert. Dieser Mechanismus erklärt, weshalb viele Gastmoleküle mit so unterschiedlichen Eigenschaften eingeschlossen werden und wird im Zusammenhang mit der Enzym-Substrat-Wechselwirkung diskutiert.
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 2811-2821 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Tetrafluoro-1,2-ethanedisulfenyl Dichloride - a Precursor for new Sulfur-Nitrogen-Carbon Heterocycles1,3,2-Dithiazolidines (3a-c) are obtained by reaction of the title compound CISCF2CF2SCI 1 with disilylated amines (Me3Si)2NR (R=Me, Ph, SiMe3). Reaction with (Me3-SiNR)2SO2 (R=Me, SiMe3) yields 1,3,5,2,4-trithiadiazepanes 4a, b, whereas N,N′-disilylated urea leads to the dithiadiazepanon 5. CISCF2CF2SSCI and SO2[N(SiMe3)2]2 react to yield the eight-membered tetrahiadiazocane 6. Using the dilution principle, with disilylated piperazine 7 in a molar ratio of 1:1 the sixteen-membered ring 9 is formed, which contains two piperazine units within the ring skeleton. The crystal structure of 1,3,5,2,4-trithiadiazepane-tetraphenylphosphonium chloride 10 is reported. 4b reacts with 1 to yield 11 in which a ten-membered ring is bridged by an SO2 group. By changing the reaction conditions a product of twice the molecular weight is formed, for which a tricyclic system with a central fourteen-membered ring 13 is proposed.
    Notes: Die Titelverbindung CISCF2CF2SCI 1 reagiert mit disilylierten Aminen (Me3Si)2NR (R=Me, Ph, SiMe3) glatt zu 1,3,2-Dithiazolidinen (3a-c). Bei der Umsetzung mit (Me3SiNR)2SO2 (R=Me, SiMe3) werden die 1,3,5,2,4-Trithiadiazepane 4a, b erhalten; mit N,N′-disilyliertem Harnstoff bildet sich das 1,5,2,4-Dithiadiazepanon 5. CISCF2CF2SSCI und SO2[N(SiMe3)2]2 reagieren zum achtgliedrigen 1,2,4,6,3,5-Tetrathiadiazocan 6. Durch Anwendung des Verdünnungsprinzips wird mit disilyliertem Piperazin 7 im Molverhältnis 1:1 der sechzehngliedrige Ring 9 synthetisiert, welcher zwei Piperazineinheiten im Ringgerüst enthält. Von 1,3,5,2,4-Trithiadiazepan-Tetraphenylphosphoniumchlorid 10 wird die Röntgenstrukturanalyse mitgeteilt. 4b reagiert mit 1 zu 11; hier liegt ein zehngliedriger Ring vor, der durch eine SO2-Gruppe überbrückt ist. Bei veränderter Reaktionsführung erhält man ein Produkt der doppelten Molekülmasse, dem eine tricyclische Struktur zugeschrieben wird, die einen zentralen vierzehngliedrigen Ring enthält (13).
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 1411-1414 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Adduct of Tin Tetrachloride and Bis(trimethylsilyl)sulfur DiimideBoth (CH3)3SiNSO and (CH3)3SiN=S=NSi(CH3)3 react with SnCl4 to yield the 1 : 1 adduct (CH3)3SiN=S=NSi(CH3)3 · SnCl4 (1). An X-ray analysis shows that the sulfur diimide functions as a bidentate ligand. 1 crystallizes in the space group P21/m with unit-cell constants a = 663.7(1), b = 1998.9(3), c = 696.7(1) pm, and β = 94.18(2)°.
    Notes: Sowohl (CH3)3SiNSO als auch (CH3)3SiN=S=NSi(CH3)3 reagieren mit SnCl4 unter Bildung des 1 : 1-Adduktes (CH3)3SiN=S=NSi(CH3)3 · SnCl4 (1). Eine Einkristallröntgenstrukturanalyse zeigt, daß das Schwefeldiimid als zweizähniger Ligand fungiert. 1 kristallisiert in der Raumgruppe P21/m mit den Zellkonstanten a = 663.7(1), b = 1998.9(3), c = 696.7(1) pm und β = 94.18(2)°.
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  • 6
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Polyspiranes, 7. Cascade Rearrangements, 2: From Polyspiranes to Polycycles - Sixfold 1,2-Shifts in Functionalized Pentaspiro[2.0.2.0.2.0.2.0.2.1]hexadecanesThe pentaspirohexadecanes 3a, b may be rearranged to 8a, b via 7a, b, which are potential precursors of the [6.4]coronane 1. 7a and 8a were benzoylated to give 7d and 8e, respectively, the molecular structures of which were determined by X-ray analysis. 7a, b and 8a, b adopt the all-cis-configuration. 7a and 7b contain axial hydroxyl groups. The overall rearrangements of 3a, b may thus be described in terms of sixfold 1,2-shifts with inversion at both the migration origins and termini.
    Notes: Die Pentaspirohexadecane 3a, b können über 7a, b in 8a, b umgelagert werden. 7a, b sind potentielle Vorläufer des [6.4]Coronans 1. 7a und 8a wurden zu 7d bzw. 8e benzoyliert, die Molekülstrukturen von 7d und 8e röntgenographisch bestimmt. 7a, b und 8a, b sind all-cis-konfiguriert, 7a und 7b enthalten die Hydroxylgruppe axial gebunden. Die Gesamtumlagerungen von 3a, b können demnach als sechsfache 1,2-Verschiebungen unter Inversion am jeweiligen Ausgangs- und Endpunkt der Umlagerung beschrieben werden.
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 117 (1984), S. 1583-1590 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: (Disilylamino)phosphanes (Rf)2P - N(SiMe3)2 - Precursors for PN3S2 RingsThe reactions of the (disilylamino)phosphanes (Rf)2P - N(SiMe3)2 (Rf = CF3, C2F5) with S3N2Cl2 lead to new cyclophosphadithiatriazenes of composition (Rf)2PN3S2 (1a, b) with elimination of Me3SiCl and S8. By-products are (Rf)2P(Cl) = NSiMe3 (2a, b). Reaction of 1a, b with norbornadiene yields 1:1 adducts 3a, b. The X-ray structure analysis of 3a (Rf = CF3) is reported. When 1a is allowed to stand for several days a crystalline compound of composition [(CF3)2PN2S]2 (4) is formed. The X-ray structure analysis shows that 4 contains an eight-membered ring with 1,3-P(CF3)2 groups.
    Notes: Aus den (Disilylamino)phosphanen (Rf)2P - N(SiMe3)2 (Rf = CF3, C2F5) und S3N2Cl2 werden unter Abspaltung von Me3SiCl und S8 neue Cyclophosphadithiatriazene der Zusammensetzung (Rf)2PN3S2 (1a, b) erhalten. Als Nebenprodukte treten Phosphanimide (Rf)2P(Cl) = NSiMe3 (2a, b) auf. 1a, b bilden mit Norbornadien 1:1-Addukte 3a, b. Die Röntgenstrukturanalyse von 3a (Rf = CF3) wird mitgeteilt. Aus 1a bildet sich nach mehrtägigem Stehenlassen eine kristalline Verbindung [(CF3)2PN2S]2 (4), deren Röntgenstrukturbestimmung einen achtgliedrigen Ring mit 1,3-P(CF3)2-Gruppen zeigt.
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  • 8
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reactions of Metal and Metalloid Compounds with Polyfunctional Molecules, XXXVIII. The Reaction of Ethanediamides with BromodimethylboraneReactions of symmetrically substituted N,N′-dialkyl-(diaryl)ethanediamides A with bromodimethylborane are investigated. Reactions in the molar ratio of 1 : 2 yield the 2,6-dioxonia-4,8-diaza-3,7-diboratabicyclo[3.3.0]octanes 1a - j, the N,N′-bis(dimethylboryl)-N,N′-diorganylethanediamides 4a, b, and the equilibrium mixtures 3a - d. By-products are 2-oxonia-4-oxa-6-azonia-8-aza-3,7-diboratabicyclo[3.3.0]octanes 2a - j. By the reaction of N,N′-diorganylethanediamides with bromodimethylborane in the molar ratio 1 : 1 the 1-oxonia-3-aza-2-boratacyclopentan-4-one derivatives 5a - e, N-(dimethylboryl)-N,N′-diorganylethanediamides 6a - c, the equilibrium mixtures 7a - d, and the 5-(alkylamino)-4-(alkylimonio)-2,2-dimethyl-1-oxonia-3-oxa-2-boratacyclopentane bromides 8a - h are obtained. X-ray analyses have been carried out for 1a, 5a, e and 8b.
    Notes: Es werden Reaktionen symmetrisch substituierter N,N′-Dialkyl-(Diaryl)ethandiamide A mit Bromdimethylboran untersucht. Die Reaktion im Molverhältnis 1 : 2 führt zu 2,6-Dioxonia-4,8-diaza-3,7-diboratabicyclo[3.3.0]octanen 1a - j, N,N′-Bis(dimethylboryl)-N,N′-diorganylethandiamiden 4a, b und den Gleichgewichtsmischungen 3a - d. Als Nebenprodukte treten 2-Oxonia-4-oxa-6-azonia-8-aza-3,7-diboratabicyclo[3.3.0]octane 2a - j auf. Bei der Umsetzung von N,N′-Diorganylethandiamiden mit Bromdimethylboran im Molverhältnis 1 : 1 erhält man die 1-Oxonia-3-aza-2-boratacyclopentan-4-on-Derivate 5a - e, N-(Dimethylboryl)-N,N′-diorganylethandiamide 6a - c, Gleichgewichtsmischungen 7a - d und 5-(Alkylamino)-4-(alkylimonio)-2,2-dimethyl-1-oxonia-3-oxa-2-boratacyclopenta n-bromide 8a - h. Für 1a, 5a, e und 8 b wurden Röntgenstrukturanalysen durchgeführt.
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 2396-2406 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reactions of Hexafluoroacetone with Nitriles of Main Groups V and VIHexafluoroacetone (HFA) reacts with nitriles of group V elements like CF3P(CN)2 (1), P(CN)3 (2), and Sb(CN)3 (3) via E — CN bond cleavage to yield compounds 4 - 6. The reactions are catalyzed by triethylamine and proceed under mild conditions. A completely different reactivity is observed for Se(CN)2, where triethylamine is incorporated into the resulting compound 7. As(NCS)3 adds two molecules of HFA per ligand across the C ≡ N triple bond forming the symmetric trithioarsenite (8). The crystal structures of 4, 7, and 8 are reported.
    Notes: Hexafluoraceton (HFA) reagiert mit Nitrilen der V. Hauptgruppe, wie CF3P(CN)2 (1), P(CN)3 (2) und Sb(CN)3 (3), unter Spaltung der E — CN-Bindungen zu den Verbindungen 4 - 6. Triethylamin katalysiert die unter milden Bedingungen ablaufenden Reaktionen. Ein vollständig anderer Reaktionstyp wird im Fall des Se(CN)2 beobachtet; hier wird ein Molekül Triethylamin in die entstehende Verbindung 7 eingebaut. As(NCS)3 addiert je zwei Moleküle HFA über die C ≡ N-Dreifachbindung zum symmetrischen Trithioarsenit (8). Von 4, 7 und 8 werden die Kristallstrukturen mitgeteilt.
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  • 10
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reaction of Metal and Metalloid Compounds with Polyfunctional Molecules, XXXIII. The Reaction of Propargylamines and N-Organyl-N-(trimethylsilyl)propargylamines with Boron-Halogen and Boron-Sulfur CompoundsThe N-organyl-N-(trimethylsilyl)propargylamines 1-5 are obtained from N-organylpropargylamines with chlorotrimethylsilane and triethylamine. The reaction of 1-5 with halogenoboranes, organylhalogenoboranes, or methylbis(methylthio)borane leads to the (organylpropargylamino)boranes 6-13. On the other hand, in the reaction of N-organylpropargylamines with halogenoboranes the C≡C triple bond inserts into the halogen-boron bond and yields the 1-azonia-2-borata-3-cyclopentene system 14-19 by intramolecular coordination. N-Organyl-N(trimethylsilyl)propargylamines react with bromodimethylborane in the molar ratio 1:2 under elimination of trimethylborane to give the 1-aza-2-bora-3-cyclopentene ring system 20-24. In the reaction of N-organyldipropargylamines with halogenoboranes both C≡C triple bonds insert into boronhalogen bonds to form the 1-azonia-5-boratabicyclo[3.3.0]octa-3,6-diene system 25-38. Tripropargylamine reacts with trichloro- and tribromoborane under three-fold insertion and intramolecular coordination to yield the 3,7,10-trihalogeno-1-azonia-5-boratatricyclo[3.3.3.01,5]undeca-3,6,10-trienes 39 and 40. For 39 the X-ray structure is reported.
    Notes: N-Organyl-N-(trimethylsily)propargylamine (1-5) werden aus N-Organylpropargylaminen mit Chlortrimethylsilan unter Zusatz von Triethylamin dargestellt. Die Reaktion von 1-5 mit Halogenboranen, Organylhalogenboranen bzw. Methylbis(methylthio)boran führt zu den entsprechenden (Organylpropargylamino)-boranen 6-13. Bei der Umsetzung der nicht silylierten N-Organylpropargylamine mit Halogenboranen erfolgt dagegen Einschiebung der C≡C-Dreifachbindung in die Halogen-Bor-Bindung und intramolekulare Koordination zum 1-Azonia-2-borata-3-cyclopenten-System 14-19. N-Organyl-N-(trimethylsily)propargylamine reagieren mit Bromdimethylboran im Molverhältnis 1:2 unter Abspaltung von Trimethylboran zum 1-Aza-2-bora-3-cyclopenten-Ring 20-24. Bei der Umsetzung von N-Organyldipropargylaminen mit Halogenboranen erfolgt Einschiebung der beiden C≡C-Dreifachbindungen in zwei Bor-Halogenbindungen wobei das 1-Azonia-5-boratabicyclo[3.3.0]octa-3,6-dien-Ringsystem 25-38 entsteht. Tripropargylamin reagiert mit Trichlor- bzw. Tribromboran unter dreifacher Einschiebung und intramolekularer Koordination zum 3,7,10-Trihalogen-1-azonia-5-boratatricyclo[3.3.3.01,5]undeca-3,6,10-trien-System 39 und 40. Für 39 wird die Röntgenstruktur mitgeteilt.
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