Palladium catalysed formal 6-endo-trig approaches to pumiliotoxin alkaloids: interception of the elusive cyclopropyl intermediate

S. Feutren, H. McAlonan, D. Montgomery, Paul Stevenson

Research output: Contribution to journalArticle

23 Citations (Scopus)

Abstract

Intramolecular Heck cyclisation of (E)-vinyl bromides leads to indolizidines, related to pumiliotoxin alkaloids, in which the stereochemistry of the trisubstituted double bond undergoes inversion. A cyclopropyl intermediate, which is believed to be responsible for the double bond inversion, has been intercepted by forcing an 'early' beta-hydride elimination on this species. The relative stereochemistry of this cyclopropyl intermediate determines the regioselectivity of the final beta-hydride elimination. In this case all three beta-hydride eliminations were stereochemically permitted, giving rise to a mixture of three isomeric products, differing in the position of a double bond. (Z)-Vinyl bromides were found to be less reactive than (E)-vinyl bromides, but on cyclisation gave the required conjugated diene, with inversion of the vinyl bromide stereochemistry, as the sole reaction product. This methodology will allow rapid stereoselective access to the diene-based pumiliotoxin alkaloids.
Original languageEnglish
Pages (from-to)1129-1137
Number of pages9
JournalJournal of the Chemical Society - Perkin Transactions 1
Volume7
Issue number7
Publication statusPublished - Nov 2000

ASJC Scopus subject areas

  • Chemistry(all)

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