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Synfacts 2007(5): 0455-0455  
DOI: 10.1055/s-2007-968393
Synthesis of Natural Products and Potential Drugs
© Georg Thieme Verlag Stuttgart · New York

Synthesis of (-)-Heptemerone B

Contributor(s):Philip Kocienski, Thomas Snaddon
A. K. Miller, C. C. Hughes, J. J. Kennedy-Smith, S. N. Gradl, D. Trauner*
University of California, Berkeley, USA
Total Synthesis of (-)-Heptemerone B and (-)-Guanacastepene E
J. Am. Chem. Soc.  2006,  128:  17057-17062  
CrossrefPubMed
Further Information

Publication History

Publication Date:
24 April 2007 (online)

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Key words

ene reaction - ring-closing metathesis - conjugate addition - anodic oxidation

Significance

The heptemerones display potent fungicidal activity against Magnaprthe grisea, the plant pathogen responsible for rice blast disease. This convergent approach features a rare intramolecular anodic oxidative coupling of silyl enol ether and furan moieties (N to P). For a discussion of this reaction, see: D. L. Wright and co-workers J. Org. Chem. 2004, 69, 3726-3734.

Comment

Tin tetrachloride mediated ene reaction of chiral glyoxalate A with B gave C as the major diastereoisomer. Diastereoselective intramolecular Heck reaction of iodofuran I gave J that was converted into primary iodide K. Halogen-lithium exchange followed by addition of L gave a mixed higher-order cuprate that underwent stereo­selective 1,4-addition to cyclopentenone H affording M. Anodic oxidation of silyl enol ether N gave dihydrofuran P via putative radical cation O.

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