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Synfacts 2015; 11(8): 0787
DOI: 10.1055/s-0034-1381171
Synthesis of Natural Products and Potential Drugs
© Georg Thieme Verlag Stuttgart · New York

Synthesis of Alsmaphorazine B

Contributor(s):
Erick M. Carreira
,
Christian Ebner
Hong AY, Vanderwal CD * University of California, Irvine, USA
A Synthesis of Alsmaphorazine B Demonstrates the Chemical Feasibility of a New Biogenetic Hypothesis.

J. Am. Chem. Soc. 2015;
137: 7306-7309
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Further Information

Publication History

Publication Date:
20 July 2015 (online)

 
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Key words

alsmaphorazine B - akuammicine - Heck reaction - Cope elimination - 1,3-dipolar cycloaddition - isoxazolidine alkaloids

Significance

Alsmaphorazine B is an indole alkaloid endowed with an isoaxzolidine embedded in the hexacyclic skeleton. Biosynthetically, this natural product is believed to originate from the related alkaloid akuammicine. Hong and Vanderwal present a short synthetic route employing an oxidation/Cope elimination/cycloaddition sequence to enable the transformation of akuammicine into alsmaphorazine B.


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Comment

A previously employed intramolecular Heck reaction provided high-yielding access to acuammicine from D. Oxidation followed by SmI2-mediated deoxygenation gave alstolucines B and F. Oxidation with DMDO followed by base induced Cope elimination yielded hydroxylamine G, which upon oxidation to the nitrone underwent 1,3-dipolar cycloaddition to H. Finally, α-hydroxylation furnished alsmaphorazine B in 15 steps and 11% overall yield.


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