- Halisphingosines A and B, modified sphingoid bases from Haliclona tubifera. Assignment of configuration by circular dichroism and van't Hoff's principle of optical superposition
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Halisphingosines A (1) and B (2), modified long-chain sphingoid bases, from the marine sponge Haliclona tubifera collected in Brazil, were characterized after conversion to their N-Boc derivatives. The 2R,3R,6R configuration of halisphingosine A, a compound first reported from Haliclona sp. from South Korea, was confirmed using a novel CD approach: deconvolution of exciton coupling from mono- and trinaphthoyl derivatives obtained by derivatization of the natural product. The sensitive CD deconvolution method, applicable to submilligram samples, simultaneously predicted the relative and absolute configuration of three stereocenters in halisphingosine A with precision and accuracy. Halisphingosine B was assigned by correlation to halisphingosine A.
- Molinski, Tadeusz F.,Biegelmeyer, Renata,Stout, E. Paige,Wang, Xiao,Frota, Mario L. C.,Henriques, Amelia T.
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- Enantiodivergent biosynthesis of the dimeric sphingolipid oceanapiside from the marine sponge Oceanapia phillipensis. Determination of remote stereochemistry
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The absolute stereochemistry of oceanapiside, an antifungal α,ω-bis- aminohydroxylipid with four stereogenic centers from the marine sponge Oceanapia phillipensis Dendy, 1895, has been obtained as 2S,3R,26R,27R from development and application of a general CD method based on superposition of additive exciton couplings in perbenzoyl derivatives of bis-amino alcohols. The method allows simultaneous determination of the local relative configuration at each of the termini of the long chain bis-aminolipid and also relates the absolute configuration of the two remote termini. Oceanapiside contains erythro and threo relative configurations at C1,2 and C26,27, respectively, but opposite absolute configurations at the amino substituted carbons C2 and C27 which implies an enantiodivergent biogenesis formally derived from both D- and L-amino acids.
- Nicholas, Gillian M.,Molinski, Tadeusz F.
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p. 4011 - 4019
(2007/10/03)
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