My watch list
my.chemeurope.com  
Login  

Asymmetric Synthesis of 3-Substituted 4-Oxoesters Using the SAMP-/RAMP-Hydrazone Method

. Based on aldehydes 1a-f or ketone 1g, 3-substituted 4-oxo esters 6a-g were synthesized in three steps in moderate to good overall yield (12-50%) and in excellent enantiomeric excesses (ee > 90® 95%) by an Umpolung-strategy employing the SAMP-/RAMP-hydrazone method. The key step in the synthesis is the highly diastereoselective alkylation of lithiated SAMP-hydrazones 3a-g (chiral d2-nucleophiles) with tert-butyl bromoacetate (4) (a2-electrophile) to furnish the alkylated 3-hydrazono tert-butylesters 5a-g in good yields (58-91%) and in excellent diastereomeric excesses (de > 90® 98%). Regeneration of the carbonyl functionality by cleavage of the hydrazones 5a-g was accomplished either by acidic hydrolysis or ozonolysis to give the acid labile and oxidation-sensitive 3-substituted 4-oxo esters 6a-g in moderate yields (19-63%) and in excellent enantiomeric excesses (ee > 90® 95%). The absolute configuration of compounds6a-g were assigned by conversion of 4-oxo esters (S)-6d and (R)-6e into their corresponding known 3-substituted g-butyrolactones (S)-7d and (R)-7e.

  • Content Type Journal Article
  • Pages 15-21
  • DOI 10.1007/s007830050049
  • Authors
    • D. Enders, Institut für Organische Chemie der Rheinisch-Westfälischen Technischen Hochschule, Professor Pirlet Straße 1, D-52074 Aachen, Germany. E-mail: Enders@RWTH-Aachen.de
    • U. Baus, Institut für Organische Chemie der Rheinisch-Westfälischen Technischen Hochschule, Professor Pirlet Straße 1, D-52074 Aachen, Germany. E-mail: Enders@RWTH-Aachen.de
    • P. Müller, Institut für Organische Chemie der Rheinisch-Westfälischen Technischen Hochschule, Professor Pirlet Straße 1, D-52074 Aachen, Germany. E-mail: Enders@RWTH-Aachen.de
    • K.C. Nicolaou
    • B. Jandeleit
    • Journal Molecules Online
    • Online ISSN 1433-1373
    • Journal Volume Volume 2
    • Journal Issue Volume 2, Number 1

Authors:   D. Enders, U. Baus, P. Müller, K.C. Nicolaou, B. Jandeleit
Journal:   Molecules Online
Year:   2004
DOI:   10.1007/s007830050049
Publication date:   19-Feb-2004
Facts, background information, dossiers
More about Springer-Verlag
Your browser is not current. Microsoft Internet Explorer 6.0 does not support some functions on Chemie.DE