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Synthesis 1996; 1996(2): 209-214
DOI: 10.1055/s-1996-4195
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A Short Asymmetric Synthesis of Both Enantiomers of Ramulosin and Its Analogues

Dieter Enders* , Anja Kaiser
  • *Institut für Organische Chemie, Rheinisch-Westfälische Technische Hochschule, Professor-Pirlet-Straße 1, D-52074 Aachen, Germany, Fax +49(241)8888127, E-mail: Enders@RWTH-Aachen.de
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Publication History

Publication Date:
31 December 2000 (online)

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(+)-Ramulosin, a metabolite of Pestalotia ramulosa, and its enantiomer have been synthesized in high enantiomeric purity (ee ≥ 98%) via Michael addition of metalated acetone SAMP-hydrazone (S)-1a to the acetal protected cyclic enoate 2 and subsequent diastereoselective reductive lactonization with L-Selectride. 3-Substituted hexahydroisocoumarines (3S,4aR)-5, analogues of ramulosin, were also obtained with excellent stereoselectivities (de ≥ 98%, ee ≥ 96%) using this method.

(+)-ramulosin - hexahydroisocoumarines - SAMP/RAMP-hydrazones - Michael addition - asymmetric synthesis