Uenishi J, Iwamoto T, Tanaka J. Total synthesis of (-)-zampanolide and questionable existence of (-)-dactylolide as the elusive biosynthetic precursor of (-)-zampanolide in an Okinawan sponge.
Org Lett 2009;
11:3262-5. [PMID:
19586001 DOI:
10.1021/ol901167g]
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Abstract
A new and concise total synthesis of (-)-zampanolide, (-)-1, and (-)-dactylolide, (-)-2, is described. Synthetic highlights include (i) a mild Horner-Wadsworth-Emmons reaction providing the seco acid, (ii) an unusual stepwise cross-coupling reaction of a 1,1-dibromodiene with inversion of olefin geometry, and (iii) specific O-Michael reaction conditions using catalytic LHMDS with TMEDA for the synthesis of functionalized 2,6-cis-tetrahydropyran. A marine sponge extract was analyzed for the presence of (-)-2 as the biosynthetic precursor of (-)-zampanolide.
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