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Synfacts 2007(8): 0795-0795
DOI: 10.1055/s-2007-968721
DOI: 10.1055/s-2007-968721
Synthesis of Natural Products and Potential Drugs
© Georg Thieme Verlag Stuttgart · New YorkSynthesis of UCS 1025A
Contributor(s):Philip Kocienski, Indu DagerR. M. de Figueiredo, R. Fröhlich, M. Christmann*
RWTH Aachen and Westfälische Wilhelms-Universität Münster, Germany
Efficient Synthesis and Resolution of Pyrrolizidines
Angew. Chem. Int. Ed. 2007, 46: 2883-2886
RWTH Aachen and Westfälische Wilhelms-Universität Münster, Germany
Efficient Synthesis and Resolution of Pyrrolizidines
Angew. Chem. Int. Ed. 2007, 46: 2883-2886
Further Information
Publication History
Publication Date:
24 July 2007 (online)
Key words
enolization - iodolactonization - aldols - conjugate addition
Significance
UCS 1025A is isolated from the fermentation broth of the Acremonium sp. KY 4917 fungus and possesses antiproliferative activity. The key step is a soft enolization-aldol condensation transforming maleimidobutyric acid A to the pyrrolizidine C.
Comment
Trituration of a weakly scalemic mixture of C (40% ee) with pentane resulted in dissolution of (-)-C whilst racemic C remained as a solid. Triethylboron-catalyzed aldol coupling between E and aldehyde F provided intermediate G which delivered UCS 1025A in two further steps.