Synfacts 2016; 12(4): 0329
DOI: 10.1055/s-0035-1561834
Synthesis of Natural Products and Potential Drugs
© Georg Thieme Verlag Stuttgart · New York

Synthesis of Ileabethoxazole, Pseudo-pteroxazole, and seco-Pseudopteroxazole

Contributor(s):
Erick M. Carreira
,
Christian Ebner
Yang M, Yang X, Sun H, Li A * Shanghai Institute of Organic Chemistry and China Pharmaceutical University, Nanjing, P. R. of China
Total Synthesis of Ileabethoxazole, Pseudopteroxazole, and seco-Pseudopteroxazole.

Angew. Chem. Int. Ed. 2016;
55: 2851-2855
Further Information

Publication History

Publication Date:
15 March 2016 (online)

 

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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