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Synfacts 2021; 17(01): 0003
DOI: 10.1055/s-0040-1719262
Synthesis of Natural Products and Potential Drugs

Synthesis of (±)-Leonuketal

Rezensent(en):
Erick M. Carreira
,
Manuel Freis
Grant PS, Furkert DP, *, Brimble MA. * University of Auckland and Maurice Wilkins Centre for Molecular Biodiscovery, Auckland, New Zealand
Total Synthesis of (±)-Leonuketal.

Org. Lett. 2020;
22: 8735-8740
DOI: 10.1021/acs.orglett.0c03364.
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Key words

(±)-leonuketal - 8,9-seco-labdane terpenoid - titanium catalysis - Shapiro reaction - fragmentation - gold catalysis - spiroketalization

Significance

The tetracyclic 8,9-seco-labdane terpenoid (−)-leonuketal was isolated from the Chinese liverwort Leonurus japonicus and shows significant vasorelaxant activity against KCl-induced contraction of rat aorta. The authors present the first total synthesis relying on a Ti-mediated cyclization, a Shapiro reaction–fragmentation and an Au-catalyzed spirocyclization.


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Comment

Epoxide A was subjected to Ti-mediated radical cyclization to obtain bicyclic ketone B. Shapiro reaction–fragmentation was applied to furnish alkyne D. Alkylation of ketoester F with iodide E afforded alkyne G which was cyclized to butenolide H. Au-catalyzed spirocyclization delivered spiro­ketal I which was transformed into the natural product in additional 9 steps.


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Publikationsverlauf

Artikel online veröffentlicht:
16. Dezember 2020

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