Preparation of chiral bipyridine bis-N-oxides by oxidative dimerization of chiral pyridine N-oxides

Research output: Contribution to journalArticle

Abstract

The direct preparation of chiral 2,2′-bipyridine bis-N-oxides has been developed. The method involves two stages, first, the deprotonation of substituted chiral pyridine N-oxides and second, the oxidative dimerization of the resulting 2-lithiopyridine N-oxides. Optimization of the reaction conditions led to the selection of LiTMP in THF for the deprotonation and molecular iodine as the oxidant. The corresponding 2-iodopyridine N-oxide is invariably formed as a by-product. A series of 11 chiral pyridine N-oxides was prepared that bear substituents at the C(2) and C(5) positions. Oxidative dimerization of these mono-N-oxides proceeded in 33-77% yield. In all cases, the dimerization was highly diastereoselective for the formation of the P-configuration of the chiral axis.

Original languageEnglish (US)
Pages (from-to)687-707
Number of pages21
JournalTetrahedron Asymmetry
Volume17
Issue number4
DOIs
StatePublished - Feb 20 2006

ASJC Scopus subject areas

  • Catalysis
  • Physical and Theoretical Chemistry
  • Organic Chemistry
  • Inorganic Chemistry

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