Phorbasides A-E, cytotoxic chlorocyclopropane macrolide glycosides from the marine sponge Phorbas sp. CD determination of C-methyl sugar configurations

John B. MacMillan, Xiong Zhou Guang, Colin K. Skepper, Tadeusz F. Molinski

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Abstract

(Chemical Equation Presented) Five new cytotoxic macrolide glycosides phorbasides A-E (3-7), each possessing a macrolide ring appended to a rare ene-yne-trans-2-chlorocyclopropane, were isolated from the same Western Australian sponge (Phorbas sp.) that provided phorboxazoles A and B. The structures of 3-7 were solved by analysis of spectroscopic data including NMR, MS, and CD. A synthesis of methyl 2-O-methyl-α-L-evalose from L-rhamnose was completed and used for configurational assignment of the sugar residue in 3. Acid-catalyzed methanolysis of 3 followed by two-step derivatization of the liberated O-methyl glycoside gave a vicinal 4-O-naphthoyl/tertiary 3-N-(2-aminonaphthyl)carbamate derivative that exhibited exciton coupled CD identical with that of the derivative prepared from synthetic 1,2-O-dimethyl-α-L-evalose.

Original languageEnglish (US)
Pages (from-to)3699-3706
Number of pages8
JournalJournal of Organic Chemistry
Volume73
Issue number10
DOIs
StatePublished - May 16 2008

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ASJC Scopus subject areas

  • Organic Chemistry

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