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Synfacts 2019; 15(01): 0001
DOI: 10.1055/s-0037-1611371
Synthesis of Natural Products and Potential Drugs
© Georg Thieme Verlag Stuttgart · New York

Synthesis of Isopalhinine A and Palhinine D

Contributor(s):
Erick M. Carreira
,
Matthieu J. R. Richter
Chen C.-M, Shiao H.-Y, Uang B.-J, Hsieh H.-P. * National Health Research Institutes, Zhunan and National Tsing Hua University, Hsinchu, Taiwan
Biomimetic Syntheses of (±)-Isopalhinine A, (±)-Palhinine A, and (±)-Palhinine D.

Angew. Chem. Int. Ed. 2018;
57: 15572-15576
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Further Information

Publication History

Publication Date:
14 December 2018 (online)

 
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Key words

Lycopodium alkaloids - (±)-isopalhinine A - (±)-palhinine D - Claisen rearrangement - oxidative dearomatization - Diels–Alder reaction - acyl radical cyclization

Significance

Isopalhinine A and palhinine D are Lycopodium alkaloids with highly bridged carbon frameworks that incorporate a 5/6/6 tricycle along with a hemiaminal moiety. Hsieh and co-workers report concise syntheses of both alkaloids, which rely on an oxidative dearomatization/[4+2] cyclo­addition strategy to construct the bicyclo[2.2.2]octane core.


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Comment

9-exo-Tet cyclization of D under basic conditions furnished the azonane ring in E. Subsequent oxidation with hypervalent iodine gave a masked ortho-benzoquinone intermediate that ­underwent Diels–Alder reaction with acrolein to ­afford F. Employing Tomioka’s method, acyl radical cyclization of aldehyde I furnished the ­characteristic isotwistane core in K.


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