ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Versuche zur Synthese von Calicen aus trisubstituierten Cyclopropanen und Cyclopentenon56. Mitt. über Fulvene, Fulvalene; 55. Mitt. [1]: Kurzmitt. (1989)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 72 (1989), S. 41-50 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Attempted Synthesis of Calicene from Trisubstitued Cyclopropanes and CyclopentenoneThe Li carbenoids 4, prepared by treatment of substituted 1,1-dihalocyclopropanes with BuLi, are reacted with cyclopent-2-enone under thermodynamic and kinetic control (Scheme 1). In general, the latter procedure gives better yields of cyclopropylcyclopentenols 5a-e, but the reaction seems to be controlled mainly by the steric and electronic properties of the substituent Y. So, with 4b and 4e, the main reaction is the attack of the carbenoid at C(1) of cyclopent-2-enone, while 4a (Y = PhS) predominantly deprotonates the ketone (Scheme 4). Whereas 5d and 5e can easily be converted to the dihydrocalicenes 6d and 6e (Scheme 6), the attempted elimination of H2O from 5a-c leads to the rearranged products 13-2 due to the opening of the cyclopropane ring (Scheme 5). Finally, the generation of the parent compound 2 from the silylated precursor 6d is attempted: treatment with MeO- gives the addition products 18A/18B, while the reaction with Br2 provides 19 by a bromination/dehydrobromination sequence (Scheme 7).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19890720106
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    8-Substituted Xanthines as Phosphodiesterase Inhibitors: Conformation-Dependent Lipophilicity and Structure-Activity RelationshipsPresented in preliminary from at the 7th European Symposium on Quantitative Structure-Activity Relationships, Interlaken, September, 1998. (1989)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 72 (1989), S. 507-517 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 8-substituted xanthines 1-21 (including compound S 9795), caffeine (22), and the three isomeric dimethyl-xanthines 23-25 (see Table 1), were examined for their lipophilic behaviour using a reversed-phase HPLC technique. A number of flexible compounds showed a smaller-than-expected lipophilicity which based on conformational and tautomeric calculations were ascribed to the predominance of folded forms. A QSAR analysis of the phosphodiesterase-inhibitory potency of several compounds showed favourable factors to be a low lipophilicity and the absence of a substituent on the N7 position.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19890720314
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Dimere Phospha- und Thiastannylene: Ylidartige Diphospha- und Dithiadistannetane (1985)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 1045-1049 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Dimeric Phospha- and Thiastannylenes: Ylide-type Diphospha- and DithiadistannetanesBis(di-tert-butylphosphino)tin(II) (1) is obtained from the reaction of potassium di-tert-butyl-phosphide with stannous chloride or with the stannous chloride-triethylphosphane complex. Bis(tert-butylthio)tin(II) (2) is prepared by reaction of (η5-C5H5)2Sn with 2-methyl-2-propanethiol or from stannous chloride and (tert-butylthio)trimethylsilane. In solution, 1 and 2 are PR2-and SR-bridged dimers, respectively. NMR spectra indicate that rapid scrambling of terminal and bridging substituents occurs in 2 but not in the cyclic \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm P}\limits^ + - \mathop {\rm S}\limits^{\rm - } {\rm n} $\end{document} ylide 1.
    Notes: Bis(di-tert-butylphosphino)zinn(II) (1) entsteht durch Reaktion von Kalium-di-tert-butylphos-phid mit Zinndichlorid oder dem Zinndichlorid-Triethylphosphan-Komplex. Bis(tert-butylthio)-zinn(II) (2) wird hergestellt durch Umsetzung von (η5-C5H5)2Sn mit 2-Methyl-2-propanthiol und entsteht auch bei der Reaktion von Zinndichlorid mit (tert-Butylthio)trimethylsilan. 1 und 2 liegen in Lösung als PR2- bzw. SR-verbrückte Dimere vor. Kernresonanzspektren zeigen, daß bei dem cyclischen \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm P}\limits^ + - \mathop {\rm S}\limits^{\rm - } {\rm n} $\end{document}-Ylid 1 im Gegensatz zu 2 auch in Ethern keine raschen Platzwechselvorgänge (Brücke/terminal) ablaufen.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19851180321
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Eigenschaften von Tellur-Tellur-Bindungen, VI. Struktur und Barriere der Enantiomerenumwandlung von Bis(2,4,6-tri-tert-butylphenyl)ditellan (1988)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 121 (1988), S. 11-14 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Properties of Tellurium-Tellurium Bonds, VI.  -  Structure and Barrier of Interconversion of Enantiomeric Conformations of Bis(2,4,6-tri-tert-butylphenyl)ditellaneOxidation of lithium (2,4,6-tri-tert-butylphenyl)telluride provides red and strong refractive needles of bis(2,4,6-tri-tert-butylphenyl)-ditellane (1) which crystallize monoclinically in the space group C2/c. The bond distance d(Te-Te), the bond angle at the Te atoms, and the torsion angle at the Te-Te bond were found to be 271.3 pm, 100.6°, and 92.1°, respectively. The C2 symmetry of the molecule gives rise to different chemical surroundings for both tert-butyl groups in ortho position belonging to the aryl groups. This effect can also be observed in solution at low temperatures. For the first time, dynamic NMR spectroscopy succeeded in determination of the barrier of rotation about a Te-Te bond. This barrier was found to be 40.9 kJ · mol-1 and is 20% less than that in the corresponding diselane.
    Notes: Bis(2,4,6-tri-tert-butylphenyl)ditellan (1) wird durch Oxidation von Lithium-(2,4,6-tri-tert-butylphenyl)tellurid in Form roter, stark lichtbrechender Kristalle erhalten. 1 kristallisiert monoklin in der Raumgruppe C2/c. Der Bindungsabstand d(Te-Te) beträgt 271.3 pm, der Bindungswinkel an den Te-Atomen 100.6° und der Torsionswinkel an der Te-Te-Bindung 92.1°. Durch die C2-Symmetrie besitzen die beiden ortho-ständigen tert-Butylgruppen der Substituenten unterschiedliche chemische Umgebung, die auch in Lösung bei tiefen Temperaturen erkennbar wird. Aus NMR-spektroskopischen Daten gelang erstmals die Bestimmung der Rotationsbarriere um eine Te-Te-Bindung; sie beträgt 40.9 kJ · mol-1. Dieser Wert ist um 20% kleiner als für das entsprechende Diselan.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19881210103
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Eigenschaften von Chalkogen-Chalkogen-Bindungen, XI. Iod[tris(trimethylsilyl)methyl]selan: Synthese des ersten Alkylselenenyliodids (1988)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 121 (1988), S. 2109-2110 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Iodo[tris(trimethylsily)methyl]selane: Synthesis of the First Alkylselenenyl IodideBis[tris(trimethylsilyl)methyl]diselane (1) reacts with elemental iodine to provide iodo[tris(trimethylsilyl)methyl]selane (2) in high yield. 2 is the first iodoselane that does not suffer from redismutation equilibria in solution at ambient temperature with iodine and the parent diselane.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19881211206
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Synthèse des (R)- et (S)-O-isopropylidène-1,2-glycérols. Détermination de la pureté optique (1985)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 1863-1871 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of the (R)- and (S)-Glycerol Acetonides. Determination of the Optical PurityThe optical purity of (R)-glycerol acetonide (1) and (S)-glycerol acetonide (1′) has been determined with great accuracy by gas chromatography after derivatization. The optical purity of (S)-glycerol actonide prepared from D-mannitol was 〉 99.4% while for (R)-glycerol acetonide obtained from L-serine it was 95%.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19850680708
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    2,2′-Bifurylidene-5,5′-diones, Coumarins, 3a, 7a-dihydro-1H-inden-1-ones, and 5H-furo[3,2-b]pyran-5-ones from propyne and carbon monoxideDedicated to Dr. G. Ohloff on the occasion of his 65th birthday (1989)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 72 (1989), S. 811-824 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The [Co2 (CO)8]-catalyzed reaction between propyne and CO in acetone at 110° and 170 bar was re-investigated. There are five major products: (E)-3,4′-dimethyl-2,2′-bifurylidene-5,5′-dione (4), 3,5,8-trimethylcoumarin (8), 3a, 7a-dihydro-2,4,7,7a-tetramethyl-1H-inden-1-one (9), 2,6-dimethyl-5H-furo [3,2, -b]- pyran-5-one (11), and 2,7-dimethyl-5H-furo 3,2-b-pyran-5-one (12); of these, only one, 4. had previously been recognized. In parallel experiments were obtained 2,6-dipentyl-5 H-furo[3,2-b]pyran-5-one (13), 2,7-dipentyl-5H-furo[3,2-b]pyran-5-one (14), 3a, 7a-dihydro-2,4,7,7a-tetrapentyl-1H-inden-1-one (15). And 3a, 7a-dihydro-2,4,6,7a-tetrapentyl-1H-inden-1-one (16) from hept-1-yne, and two further types of products from two atypical 1-alkynes: 3,6,9-tri(tert-butyl)-1-oxaspiro[4.4]nona-3,6,8-trien-2-one (20) from (tert-butyl)acetylene and the exo-dimer 21 of 2,5-bis(trimethylsilyl)cyclopenta-2,4-dien-1-one (22) from (trimethylsilyl)acetylene. Compounds 11,12, and 20 were identified by X-ray analysis.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19890720423
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Herstellung, optische Reinheit und Konfiguration der Flecainid-Enantiomeren (1985)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 4616-4619 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Preparation, Optical Purity and Configuration of the Enantiomers of FlecainideThe chiral antiarrhythmic drug flecainide (rac-1) was resolved by fractional crystallization of the diastereomeric salts with optically active mandelic acid. Derivatization with (+)-1-phenylethyl isocyanate and analytical separation of the diastereomers 3 by HPLC on silica gel confirmed the optical purity of the enantiomers. CD-Spectra of the N-chloro derivatives established the absolute configuration: (-)-1 is R-, (+)-1 S-configurated.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19851181132
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Konfiguration der Praziquantel-Enantiomeren (1985)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 4620-4622 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Configuration of the Praziquantel EnantiomersThe levorotatory (methanol) enantiomer of the anthelminthic agent praziquantel (rac-1) is R-, the dextrorotatory S-configurated. This assignment is based upon CD-spectra of both enantiomers and additionally confirmed by conversion of (+)- and (-)-2 to the pyrazinoisoquinolines 3 of known configuration.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19851181133
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Darstellung von cis-Dichloro[tellurobis(di-tert-butyl-phosphan)]platin(II) (1985)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 5016-5017 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Preparation of cis-Dichloro[tellurobis(di-tert-butylphosphane)]platinum(II)The title complex 2 is obtained in 50-60% yield from heterogeneous reactions between tellurobis(di-tert-butylphosphane) (1) and bis(benzonitrile)dichloroplatinum(II) in methylene chloride or platinum dichloride in toluene suspension. NMR and MS data are consistent with a chelate-type Cl2Pt(tBu2P)2Te structure of the new complex.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19851181233
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...