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  • 1
    Electronic Resource
    Electronic Resource
    Asymmetric Michael Additions via SAMP-/RAMP-Hydrazones Enantioselective Synthesis of β-Substituted Δ-Oxopentanoates and δ-Lactones1) (1987)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 120 (1987), S. 1223-1227 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Asymmetrische Michael-Additionen via SAMP-/RAMP-Hydrazone. - Enantioselektive Synthese von β-substituierten δ-Oxopentausäureestern und δ-Lactonen1)Asymmetrische Michael-Addition von metalliertem Acetaldehyd-SAMP- oder -RAMP-Hydrazon (S)- oder (R)-2 an α,β-ungesättigte Carbonsäureester 3 liefert nach anschließender oxidativer Spaltung durch Ozonolyse die β-substituierten δ-Oxopentansäureester (R)- oder (S)-5 in hohen Enantiomerenüberschüssen (ee = 90 bis ≧ 96%). Racemisierungsfreie Reduktion und Cyclisierung führt zu den entsprechenden optisch aktiven δ-Lactonen (R)- oder (S)-7.
    Notes: Asymmetric Michael addition of metalated acetaldehyde SAMP- or RAMP-hydrazone (S)- or (R)-2 to α,β-unsaturated esters 3 and subsequent oxidative cleavage by ozonolysis yields the β-substituted δ-oxopentanoates (R)- or (S)-5 with high enantiomeric excesses (ee = 90 to ≧ 96%). Racemization-free reduction and cyclization affords the corresponding optically active δ-lactones (R)- or (S)-7.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19871200718
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  • 2
    Electronic Resource
    Electronic Resource
    Asymmetric Michael Additions via SAMP-/RAMP-Hydrazones Enantioselective 1,4-Addition of Methyl Ketones to Knoevenagel Acceptors1) (1987)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 120 (1987), S. 1731-1735 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Asymmetrische Michael-Additionen via SAMP-/RAMP-Hydrazone. - Enantioselektive 1,4-Addition von Methylketonen an Knoevenagel-Akzeptoren1)Asymmetrische Michael-Addition von lithiierten Methylketon-SAMP-Hydrazonen (S)-2 an 2-Benzylidenmalonsäureester und -dinitrile 3 und anschließende oxidative Spaltung der 1,4-Addukte (SR)-4 durch Ozonolyse liefert 2-substituierte 4-Oxodiester und -dinitrile (R)-5 in guten Gesamtausbeuten von 50-82% und hohen Enantiomerenüberschüssen (ee ≧ 95%).
    Notes: Asymmetric Michael addition of lithiated methyl ketone SAMP-hydrazones (S)-2 to 2-benzylidenemalonates and -dinitriles 3 followed by oxidative cleavage of the 1,4-adducts (SR)-4 by ozonolysis affords 2-substituted 4-oxo diesters and -dinitriles (R)-5 in good overall yields of 50-82% and high enantiomeric excesses (ee ≧ 95%).
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19871201019
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
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