Synthesis of (+)-1-epiaustraline

S. E. Denmark, J. J. Cottell

Research output: Contribution to journalArticle

Abstract

A highly efficient total synthesis of (+)-1-epiaustraline ((+)-1), a tetrahydroxypyrrolizidine alkaloid of the alexine/australine subclass, is described. The key step is a tandem intramolecular [4 + 2]/intermolecular [3 + 2] nitroalkene cycloaddition involving dienylsilyloxy nitroalkene 3 and chiral vinyl ether 4, which establishes four of the five stereocenters present. The final center was installed by a diastereoselective dihydroxylation. Hydrogenolytic unmasking of the nitroso acetal tosylate 17 containing the silyl ether linkage was thwarted by a slow alkylation and an undesired Peterson-type elimination. Prior removal of the silicon moiety by Tamao-Fleming oxidation proceeded in excellent yield and provided a substrate suitable for hydrogenolysis and deprotection. The complete synthesis required only 10 steps to deliver the (+)-1-epiaustraline in 7.0% overall yield.

Original languageEnglish (US)
Pages (from-to)4276-4284
Number of pages9
JournalJournal of Organic Chemistry
Volume66
Issue number12
DOIs
StatePublished - Jun 15 2001

ASJC Scopus subject areas

  • Organic Chemistry

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