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DOI: 10.1055/s-0035-1561834
Synthesis of Ileabethoxazole, Pseudo-pteroxazole, and seco-Pseudopteroxazole
Publikationsverlauf
Publikationsdatum:
15. März 2016 (online)
![](https://www.thieme-connect.de/media/synfacts/201604/i_c014_s1_10-1055_s-0035-1561834.gif)
Significance
The oxazole diterpenoids ileabethoxazole, pseudopteroxazole and seco-pseudopteroxazole, isolated from Pseudopterogorgia elisabethae, possess potent inhibitory activity against Mycobacterium tuberculosis. Structurally, these natural products are characterized by a hexasubstituted benzene connected to an oxazole. Li and co-workers achieved the total syntheses of these targets relying on a palladium cascade reaction followed by a 6π-electrocyclization.
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Comment
Alkyne A, available in six steps from (+)-isopulegol, undergoes a palladium-catalyzed cascade reaction to give C in 55% yield. Upon heating in the presence of air, the desired 6π-electrocyclization occurred, providing key intermediate D. Later, alkyne F was obtained, which underwent a radical cyclization ultimately leading to (+)-ileabethoxazole. Furthermore, both (+)-pseudo-pteroxazole and (+)-seco-pseudopteroxazole could be accessed from D.
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![](https://www.thieme-connect.de/media/synfacts/201604/i_c014_s1_10-1055_s-0035-1561834.gif)