Synthesis of Indolizidine Alkaloids via the Intramolecular Imino Diels-Alder Reaction

Nazir A. Khatri, Hans F. Schmitthenner, Jayant Shringarpure, Steven M. Weinreb

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94 Scopus citations

Abstract

An intramolecular imino Diels-Alder strategy has been developed for total synthesis of the indolizidine alkaloids δ-coniceine (1), tylophorine (2), elaeokanine A (3), and elaeokanine B (4). In all cases, an acyl imine dienophile was generated thermally in situ from a methylol acetate precursor. Diene-methylol acetate 8 has been cyclized via 10 to lactam 11, which was converted to δ-coniceine. Similarly, intermediate methylol acetate 18 was transformed via 19 and 20 to pentacyclic lactam 21, and then to tylophorine. In the syntheses of elaeokanine A and B, a masked diene precursor, in the form of a dihydrothiophene dioxide system, was prepared. Thus, compound 35 was cyclized via intermediate 23b to afford bicyclic lactams 37 and 39 in a 5:4 ratio. These products were subsequently converted to 3 and 4.

Original languageEnglish (US)
Pages (from-to)6387-6393
Number of pages7
JournalJournal of the American Chemical Society
Volume103
Issue number21
DOIs
StatePublished - Jan 1 1981

All Science Journal Classification (ASJC) codes

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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