Synthesis of the enantiomeric furobenzofurans, late precursors for the synthesis of (+)- and (-)-aflatoxins B1, B2, G1, and G2

Edgar R Civitello, Henry Rapoport

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Abstract

Enantiomeric tetrahydrofuro[2,3-b]benzofurans, representing the ABC tricyclic portion of aflatoxins B1, B2, G1, and G2, were generated from the oxaza-Cope rearrangement of a suitably functionalized O-aryloxime. The O-aryloxime was, in turn, made from the condensation of an enantiomerically pure aldehyde derived from glutamic acid and a substituted phenoxyamine. High regioselectivity with respect to the A-ring substituents of the ABC tricycle was achieved through the use of electrochemistry. The regioselective electrochemical cleavage of 4,6-bis(tosyloxy)-2-(methoxycarbonyl)-2,3,3a,8a-tetrahydrofuro[2,3-b]benzofuran (22) resulted in a 97/3 mixture of regioisomeric phenols. The regiochemical assignments of the resulting phenols were determined by 2D NOESY NMR. The enantiomeric ratio of the final product was determined to be 96/4 by NMR analysis of diastereomers resulting from the coupling of 31a to (+)- and (±)-phenethylamine.

Original languageEnglish (US)
Pages (from-to)3775-3782
Number of pages8
JournalJournal of Organic Chemistry
Volume59
Issue number14
StatePublished - 1994
Externally publishedYes

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ASJC Scopus subject areas

  • Organic Chemistry

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