Free radical cyclizations in alkaloid total synthesis: (±)-21- oxogelsemine and (±)-gelsemine

Shogo Atarashi, Joong Kwon Choi, Deok Chan Ha, David J. Hart, Daniel Kuzmich, Chih Shone Lee, Subban Ramesh, Shung C. Wu

Research output: Contribution to journalArticlepeer-review

79 Citations (Scopus)

Abstract

Total syntheses of (±)-21-oxogelsemine (3) and (±)-gelsemine (1) are described. Free radical cyclizations play important roles in constructing the tricyclic core (40 → 41) and oxindole (93 → 96) substructures of the target alkaloids, and an isomerization-cyclization strategy (101 → 102) was used to complete construction of the gelsemine cage. Observations made along the way include intramolecular 1,4- and 1,6-hydrogen atom transfers (64 → 65 and 40 → 47) and a free radical cyclization-fragmentation sequence (85 → 86 + 87). A retroaldol-aldol strategy for adjusting oxindole stereochemistry in gelsemine-like structures is also described (72 → 74 and 86 → 87).

Original languageEnglish
Pages (from-to)6226-6241
Number of pages16
JournalJournal of the American Chemical Society
Volume119
Issue number27
DOIs
Publication statusPublished - 1997
Externally publishedYes

ASJC Scopus subject areas

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

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