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  • 1
    Electronic Resource
    Electronic Resource
    Intra- und extraannular funktionalisierte helical-chirale [2.2]Metacyclophane: Synthese, Circulardichroismus und Struktur-Chiroptik-Beziehungen (1990)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 123 (1990), S. 1859-1868 
    Details
    ISSN: 0009-2940
    Keywords: Circular dichroism ; [2.2]Metacyclophanes ; Helical molecules ; Absolute configuration ; Structure-chiroptic relationships ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Intra- und Extraannularly Functionalized Chiral [2.2]Metacyclophanes: Synthesis, Circular Dichroism, and Structure - Chiroptic RelationshipsA simple one-step cyclization reaction for the synthesis of the title compounds 1-5 is presented; separation (enrichment) of enantiomers is achieved by HPLC mainly on (+)-PTrMA. The kinetics of interconversion (racemization) of the new dihetera[2.2]metacyclophanes are determined: No racemization of the internally substituted phanes is found on heating until decomposition, whereas the extraannularly substituted compounds exhibit barriers of interconversion of about 130 kJ/mol, similar to that of the unfunctionalized skeleton 1a. For the pyridinophane 2 the barrier (110 kJ/mol) is lower corresponding to the decreased spatial requirement of the nitrogen lone pair compared to a C-H bond. The circular dichroism curves of the intraannularly functionalized phanes are compared with those of the extraannularly functionalized reference compounds: A bathochromic shift of the Cotton effect at short wavelengths is found, which is increasing with the bulkiness of the internal functional group.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19901230918
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  • 2
    Electronic Resource
    Electronic Resource
    Deformierte chirale [n]Metacyclophane (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 759-765 
    Details
    ISSN: 0009-2940
    Keywords: Chirality ; Circular dichroism ; Conformational mobility ; Cyclophanes ; [n]Phanes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Deformed Chiral [n]MetacyclophanesThe new dithiametacyclophane 3c and the thiaazametacyclophanes 6a, b are chiral, but do not contain chirality centres. They are obtained by cyclization of 1,3-propanedithiol (2), or of the thiaza precursors 5a, b, with the bis(bromomethyl) compounds 1, 4a, b. The dynamic behaviour of the aliphatic chains in 3c, and 6a, b (flipping/rotation) have been studied by dynamic NMR. X-ray analyses of 3c and 6a document the out-of-plane deformation of the boat-shaped benzene ring. The circular dichroism of enantiomer-enriched 3c is reported.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270427
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  • 3
    Electronic Resource
    Electronic Resource
    Nitro- und Allyloxy-substituierte helicale [2.2]Metacyclophane: Synthese, Circulardichroismus und Röntgen-Kristallstrukturanalysen (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1585-1590 
    Details
    ISSN: 0009-2940
    Keywords: Charge transfer ; Circular dichroism ; Helical molecules ; [2.2]Metacyclophanes ; Structure-chiroptic relationships ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Nitro- and Allyloxy-Substituted Helical [2.2]Metacyclophanes: Synthesis, Circular Dichroism and Crystal StructuresThe preparations of the title compound 3a, intraannularly nitro-functionalized, of the extraannularly substituted reference compound 3b, and of the sulfone 4 are described. Enantiomeric resolution of these helical phanes was accomplished on (+)-PTrMA and cellulose tris(3,5-dimethylphenyl)carbamate by HPLC. Racemization of the enantiomers of 3b is faster than that of the previously reported extraannularly substituted phanes. The crystal structure of 3a as well as that of the allyl ether 3d show severe distortions of the benzene rings; the CD spectrum of 3a is pointing at an intramolecular charge-transfer complex, an effect that cannot be evaluated from the CD spectrum of 3b.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19911240719
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  • 4
    Electronic Resource
    Electronic Resource
    A Chiral Adamantanophane: Preparation, Enantiomer Separation, Theoretical and Experimental Circular Dichroism and Absolute Configuration (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 2081-2088 
    Details
    ISSN: 0009-2940
    Keywords: Adamantanophanes ; Calculations, CI ; Circular dichroism ; Cyclophanes ; Strain energy ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Exchange of aromatic units (e.g. benzene) for aliphatic/ali-cyclic building blocks (e.g. adamantane) in cyclophanes leads to molecules of the “araliphane” type. The synthesis of the highly strained [2.2](1,3)adamantanometacyclophanes 5a-c is described. The cyclophane skeletons of these molecules are conformationally rigid and therefore 5a-c are planar-chiral. The circular dichroism of 5c has been calculated theoretically with NDDO/MRD-CI methods and was measured. Agreement of theory and experiment is good, a comparison of both allows the assignment of the absolute configuration of the two enantiomers of 5c with high probability. Furthermore, analysis of the nπ* band in the CD spectrum yields a, simple general rule to determine the conformation of the carboxyl group in phenyl ester substructures. Theoretical calculations of the strain energy (Es) of 5c reveal the distribution of strain within the molecule.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941271034
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