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  • 1
    Electronic Resource
    Electronic Resource
    Ring inversion barrier in 5,5-difluoro-1,3-dioxane (1973)
    s.l. : American Chemical Society
    The @journal of organic chemistry 38 (1973), S. 4079-4081 
    Details
    ISSN: 1520-6904
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/jo00987a033
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  • 2
    Electronic Resource
    Electronic Resource
    Conformational analysis. XXXI. Conformational equilibria of 1,3-dioxanes with polar substituents at C-5 (1976)
    s.l. : American Chemical Society
    Journal of the American Chemical Society 98 (1976), S. 956-965 
    Details
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ja00420a015
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  • 3
    Electronic Resource
    Electronic Resource
    Synthesis and Stereochemistry of Novel Dibrominated 1,5-Dioxaspiro[5.5]undecane Derivatives (2000)
    Springer
    Monatshefte für Chemie 131 (2000), S. 277-286 
    Details
    ISSN: 1434-4475
    Keywords: Keywords. Spiro compounds; Diastereoselective bromination; X-Ray structure determination; Conformation; NMR Spectroscopy.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary.  The synthesis and stereochemistry of new dibrominated spiro-1,3-dioxane derivatives are reported. Investigations by means of NMR methods and single crystal X-ray diffraction for two compounds revealed the high regio- and diastereoselectivity of the bromination reaction of some new spiro-1,3-dioxanes and the asymmetric induction of the chiral carbon atom located in the spiro skeleton.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s007060070103
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  • 4
    Electronic Resource
    Electronic Resource
    The Stereochemistry of Some New Flexible 2,2,5,5-Tetrasubstituted 1,3-Dioxanes (1998)
    Springer
    Monatshefte für Chemie 129 (1998), S. 723-733 
    Details
    ISSN: 1434-4475
    Keywords: Keywords. Flipping 1 ; 3-dioxanes; Prostereogenic carbon atoms; NMR discrimination of pro-R ; pro-S ; pro-cis ; and pro-trans groups; NMR spectra with chiral shift reagents.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung.  Die Stereochemie einiger neuer 2,2,5,5-tetrasubstituierter 1,3-Dioxanderivate wurde untersucht. Spezielle Fälle von Prostereoisomerie sowie die NMR-spektroskopische Unterscheidung der pro-R-, pro-S-, pro-cis- und pro-trans-Substituenten werden diskutiert.
    Notes: Summary.  The stereochemistry of some new 2,2,5,5-tetrasubstituted 1,3-dioxane derivatives was investigated. Peculiar cases of prostereoisomerism and the NMR spectroscopic identification of pro-R, pro-S, pro-cis, and pro-trans groups are reported for these achiral flipping compounds.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00013481
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  • 5
    Electronic Resource
    Electronic Resource
    Synthesis and Stereochemistry of Some New Spiro-1,3-perhydrooxazines (2000)
    Springer
    Monatshefte für Chemie 131 (2000), S. 975-983 
    Details
    ISSN: 1434-4475
    Keywords: Keywords. Conformational analysis; Molecular chirality; 1,3-Perhydrooxazine derivatives; Spiro compounds.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary.  The synthesis and the stereochemistry of new spiro-1,3-perhydrooxazines are reported. The stereoisomerism of these compounds is discussed considering the data of conformational analysis, the helical chirality of the spiro[5.5]undecane skeleton, and the triligand virtual chiral center belonging to the 1,3-perhydrooxazine ring.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s007060070054
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  • 6
    Electronic Resource
    Electronic Resource
    Stereochemie und1H-NMR-Spektren einiger vom Pentaerythrit abgeleiteten Spiro-1,3-dioxane (1989)
    Springer
    Monatshefte für Chemie 120 (1989), S. 735-742 
    Details
    ISSN: 1434-4475
    Keywords: Spiro-1,3-dioxanes ; Pentaerythritol (a)ketals ; Conformational analysis ; Aromatic solvent induced shift — ASIS
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Mono- and trispiro-1,3-dioxanes with mobile, fixed and “semimobile” structures were obtained by the condensation reaction of pentaerythritol with aldehydes and symmetrical or unsymmetrical ketones. The conformational analysis of the obtained compounds was undertaken by means of1H-NMR spectroscopy. The spiro-1,3-dioxanes obtained with aldehydes or nonsymmetrical ketones represent fixed (“anancomeric”) structures. Ketalisation with 4-t-butyl-cyclohexanone leads to a “semimobile” structure of a trispiro-1,3-dioxane in which the two marginal cyclohexanic rings are fixed, while the two middle ones are mobile, continuously flipping at room temperature. The solvent effect on the NMR spectra is also discussed. Utilisation of benzene-d 6 makes it possible to interpret some of the complex spectra with superposed signals on the basis of the aromatic solvent induced shift (ASIS).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00809966
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  • 7
    Electronic Resource
    Electronic Resource
    Heterocycles LXXVIII. Electrophilic Substitution of 2′-Phenyl-4R-2,4′-bisthiazoles (1998)
    Springer
    Monatshefte für Chemie 129 (1998), S. 661-669 
    Details
    ISSN: 1434-4475
    Keywords: Keywords. Atropisomerism; 2 ; 4′-Bisthiazoles; Halogenation; Nitration.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung.  Zur Ermittlung von Zusammenhängen zwischen Struktur und Reaktivität der beiden Thiazolringe wurde das Verhalten einiger 2′-Phenyl-4R-2,4′-bisthiazole bezüglich elektrophiler Substitution (Halogenierung und Nitrierung) untersucht. Der Eintritt der Substituenten in die Positionen 5 bzw. 5′ des Bisthiazolsystems hängt von der Natur des Substituenten in Position 4 ab.
    Notes: Summary.  The behaviour of some 2′-phenyl-4R-2,4′-bisthiazoles with respect to electrophilic substitution reactions (halogenation and nitration) has been studied in order to establish relationships between structure and reactivity of the two thiazole rings. The entry of the electrophilic reactants in position 5 or 5′ of the 2,4′-bisthiazole system depends on the nature of the residue in position 4.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00013474
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  • 8
    Electronic Resource
    Electronic Resource
    Stereochemie und1H-NMR-Spektren einiger Spiro-1,3-Dioxane (1982)
    Springer
    Monatshefte für Chemie 113 (1982), S. 565-572 
    Details
    ISSN: 1434-4475
    Keywords: Formaldehyde generating reagent ; Solvent shifts in1H-nmr ; Spiranes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Mono and dispiro-1,3-dioxanes (1–3) were synthesized by the condensation of 1,2-, 1,3- and 1,4-cyclohexanedione, respectively (4–6) with bis-(hydroxymethyl)-malonic ester (7). The1H-NMR spectra prove for the mono- (2) and dispiro-1,3-dioxane (3) the existence of conformational equilibria and for the monospiro-1,3-dioxane (1) a “fixed” structure. C6D6 causes a remarkable solvent shift effect in the NMR spectra separating a superposed complex coupling pattern (in CDCl3) in two well resolved AB doublets and two AX quartets. TheE-oxime of the monospiro-1,3-dioxanone (1) represents also a “fixed” structure. Bis-(hydroxymethyl)-malonic ester (7) is a formaldehyde generating agent in the condensation reaction of dimedone with the diol7.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00800263
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  • 9
    Electronic Resource
    Electronic Resource
    Crystal and Molecular Structure of 2-Amino-5-butyl-3-ethyl-6-methyl-4(3H)-pyrimidinone (1998)
    Springer
    Monatshefte für Chemie 129 (1998), S. 735-740 
    Details
    ISSN: 1434-4475
    Keywords: Keywords. 2-Amino-4-pyrimidinone; Tautomerism; X-Ray crystal structure.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung.  Die Struktur von 2-Amino-5-n-butyl-3-ethyl-6-methyl-4(3H)-pyrimidinon (1) wurde roöntgenstrukturanalytisch und mittels ab intitio– Berechnungen (HF/6-31G*) untersucht. Die Roöntgenstrukturanalyse zeigt, daß1 als Amino-Oxo-Tautomer (AO) vorliegt, was mit den Ergbnissen der Rechnungen übereinstimmt. Die Kristalle von 1 sind tetragonal (Raumgruppe P42/n) mit den Zellparametern a=b=17.074 Å, c=8.809 Å und α=β=γ=90°. Der 4-Pyrimidinonring ist im Kristall planar; der Aminstickstoff und der Carbonylsauerstoff liegen in der Ringebene. Die Molekuüle der Verbindung 1 werden durch starke intermolekulare Wasserstoffbruücken verbunden, die von der NH2-Gruppe einer Einheit zur C*O-Gruppe der naächsten reichen (N–H⋯O – Abstand: 2.88 Å).
    Notes: Summary.  The structure of 2-amino-5-n-butyl-3-ethyl-6-methyl-4(3H)-pyrimidinone (1) has been studied by X-ray diffraction and ab initio calculations at the HF/6-31G* level. X-ray analysis established that 1 exists as the amino-oxo tautomer (AO) in the solid state, in good agreement with the ab initio results. Crystals of 1 are tetragonal (space group P42/n); the unit cell dimensions are a=17.074 Å, b=17.074 Å, c=8.809 Å, α=β=γ=90°. The 4-pyrimidinone ring is essentially planar in the crystal, the amino nitrogen and the carbonylic oxygen being located in the plane of the ring. The 2-amino-5-n-butyl-3-ethyl-6-methyl-4(3H)-pyrimidinone molecules are linked by strong N–H⋯O intermolecular hydrogen bonds from the NH2 group of one molecule to the C*O group of an adjacent molecule (N–H⋯O distance: 2.88 Å).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00013482
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  • 10
    Electronic Resource
    Electronic Resource
    Molecular Structure of an Isocytosine Analog: Combined X-ray Structural and Computational Study of 2-Diethylamino-6-methyl-5-n-propyl-4(3H)-pyrimidinone (1999)
    Springer
    Structural chemistry 10 (1999), S. 303-310 
    Details
    ISSN: 1572-9001
    Keywords: 2-Diethylamino-6-methyl-5-n-propyl-4(3H)-pyrimidinone ; tautomerism ; X-ray crystal structure ; ab initio and DFT calculations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The structure of 2-diethylamino-6-methyl-5-n-propyl-4(3H)-pyrimidinone has been studied by X-ray crystallography and quantum-chemical calculations. X-ray analysis established that 2-diethylamino-6-methyl-5-n-propyl-4(3H)-pyrimidinone exists exclusively as the lactam tautomer protonated at the N3 ring nitrogen in the solid state. Crystals of 2-diethylamino-6-methyl-5-n-propyl-4(3H)-pyrimidinone are monoclinic (space group P21/n); the unit-cell dimensions are: a = 11.0460(8) Å, b = 5.0064(4) Å, c = 22.8358(17) Å, α = γ = 90°, β = 90.521(1)°. In the crystal, molecules of 2-diethylamino-6-methyl-5-n-propyl-4(3H)-pyrimidinone are assembled in planar centrosymmetric dimers by strong resonance-assisted N—H···O intermolecular hydrogen bonds from the NH group of one molecule to the C=O of the adjacent molecule (N—H···O distance 2.804 Å). Bond distances and angles are generally similar to those reported for the corresponding tautomer of isocytosine and derivatives. Quantum-chemical calculations on 2-diethylamino-6-methyl-5-n-propyl-4(3H)-pyrimidinone are also reported in order to estimate the relative energies of the possible tautomeric forms; ab initio and DFT results predict the coexistence of the N3 and AH tautomers in the gas phase. There is excellent correspondence between the crystal and the HF/6-311G** or B3LYP/6-31G* calculated structures of the N3 lactam form; the largest deviations between the experimental and computed structures are mostly the effects of strong intermolecular H bonds in the crystal.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022051119505
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