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  • 1
    Electronic Resource
    Electronic Resource
    Cyclopropan-Derivate, 2. Selbst-Acylierung der α-Alkyl-γ-lactone zu Herstellung von Bis(1-alkylcyclopropyl)ketonen über Spiro[4.4]acetale (1990)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 123 (1990), S. 2161-2166 
    Details
    ISSN: 0009-2940
    Keywords: Acetals ; Ketones ; γ-Lactones ; Butanolides ; Spiro compounds ; Cyclopropyl compounds ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cyclopropane Derivatives, 2.  -  Self-Acylation of α-Alkyl-γ-lactones To Give Bis(1-alkylcyclopropyl)ketones via Spiro[4.4]acetalsHigh-yield synthetic ways are recommended for the title lactones 1.The coupling of two 2-alkyl-4-butanolides is possible in an inter-(1b, c) or intramolecular fashion (4c) to give spiro[4.4] acetals 8 or 9 respectively, in the absence of hindering substituents. Symmetrically substituted bis(1-alkylcyclopropyl)ketones 12 and 13 may be prepared by acidic cleavage of those spiro[4.4] acetals lacking 2,7-substituent.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19901231112
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  • 2
    Electronic Resource
    Electronic Resource
    Cyclopropan-Derivate, 3. (1-Alkylcyclopropyl)ketone durch Acylierung von α-substituierten γ-Lactonen (1990)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 123 (1990), S. 2167-2172 
    Details
    ISSN: 0009-2940
    Keywords: Acylation ; Ketones ; γ-Lactones ; Butanolides ; Cyclopropyl compounds ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cyclopropane Derivatives, 3.  -  (1-Alkylcyclopropyl)ketones by Acylation of α-Substituted γ-LactonesThe 2-acylation of 2-substituted 4-butanolides 2 is moderately sensitive to steric crowding, whereas the subsequent ring- opening of 2-acyl-2-alkyl-4-butanolides 4, 11 to give-chloro ketones 6, 12 by chloride-transferring acid derivatives be-comes difficult with bigger lactone substituents. Similar observations pertain to the preparation of y-chlorobutanoyl chlorides 10 from 2-alkyl-4-butanolides 2. The proper choice of the starting 4-butanolides (2a, b or 14 but not 2c) provides for an indirect coupling of two different lactones to y,y-dichloro ke-tones 12. Dicyclopropyl ketones 13 with variable patterns of substitution may thus be prepared from 4-butanolides in a direct manner with global yields exceeding 50% and without purification of intermediate products (except for acid chlorides like 10).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19901231113
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  • 3
    Electronic Resource
    Electronic Resource
    Substituent-induced chemical shifts (SCS) by the phenyl group in sterically congested styrene derivativesSterically Congested Molecules, Part 7. For Part 6, see R. Knorr et al., Chem. Ber. 126, in press (1993). (1993)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 31 (1993), S. 388-393 
    Details
    ISSN: 0749-1581
    Keywords: 13C NMR ; 1H NMR ; 9-Methylenefluorenes ; Substituent effects ; Substituent-induced chemical shifts ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The two 13C NMR methyl signals of the sterically congested 9-benzylidene-1,8-dimethylfluorene (1a) have the surprisingly small separation of only 0.37 ppm; for 9-benzylidene-2,7-dimethylfluorene the corresponding methyl separation is 0.04 ppm. An alternative analysis of 1a with respect to 1,8-dimethylfluorene shows that the perturbing syn-phenyl substituent has caused a downfield ( + 0.47 ppm) 13C shift but an upfield 1H shift ( - 0.97 ppm) of the compressed 1-CH3 group. For further comparisons, NMR assignments were also made for 2,7-dimethylfluorene, 1,8-dimethylfluoren-9-one and 2-(1,1-dimethylethyl)-3,3-dimethyl-1-phenylbut-1-ene.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1260310415
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