Tandem double intramolecular [4+2]/[3+2] cycloadditions of nitroalkenes: construction of the pentacyclic core structure of daphnilactone B

Scott E. Denmark, Ramil Y. Baiazitov, Son T. Nguyen

Research output: Contribution to journalArticle

Abstract

An asymmetric synthesis of the ABCD ring system of daphnilactone B is described. The synthesis features a tandem, double intramolecular, [4+2]/[3+2] cycloaddition of a highly functionalized, enantiomerically enriched nitroalkene to generate a pentacyclic nitroso acetal. The cycloaddition establishes six contiguous stereogenic centers including the critical CD ring junction that bears two quaternary stereogenic centers. Hydrogenolysis of the nitroso acetal followed by amide reduction and cyclization provided the AB rings. The methyl substituent on the A ring was installed in the correct configuration via hydrogenation of an exocyclic olefin in the final step.

Original languageEnglish (US)
Pages (from-to)6535-6548
Number of pages14
JournalTetrahedron
Volume65
Issue number33
DOIs
StatePublished - Aug 15 2009

Keywords

  • Alkaloid
  • Nitroalkene
  • Tandem cycloaddition

ASJC Scopus subject areas

  • Biochemistry
  • Drug Discovery
  • Organic Chemistry

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