Copper-free and amine-free Sonogashira coupling in air in a mixed aqueous medium by palladium complexes of N/O-functionalized N-heterocyclic carbenes

Manoja Samantaray, Mobin M. Shaikh, Prasenjit Ghosh*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

69 Scopus citations

Abstract

Highly convenient copper-free and amine-free Sonogashira coupling of aryl bromides and iodides with terminal acetylenes under amenable conditions in air and in a mixed aqueous medium are reported using several new, user friendly and robust palladium precatalysts (1-5) of N/O-functionalized N-heterocyclic carbenes (NHCs). In particular, the precatalysts, 1 and 2, were synthesized from the imidazolium chloride salts by the treatment with PdCl2 in pyridine in presence of K2CO3 as a base while the precatalysts, 3-5, were synthesized from the respective silver complexes by the treatment with (COD)PdCl2. The DFT studies carried out on the 1-5 complexes suggest the presence of strong NHC-Pd σ-interactions arising out of deeply buried NHC-Pd σ-bonding molecular orbitals (MOs) that account for the inert nature of the metal-carbene bonds and also provide insights into the exceptional stability of these precatalysts.

Original languageEnglish (US)
Pages (from-to)3477-3486
Number of pages10
JournalJournal of Organometallic Chemistry
Volume694
Issue number21
DOIs
StatePublished - Oct 1 2009

Keywords

  • Carbenes
  • Functionalized NHC
  • Organometallic catalysis
  • Palladium-NHC complex
  • Sonogashira coupling

ASJC Scopus subject areas

  • Biochemistry
  • Inorganic Chemistry
  • Organic Chemistry
  • Physical and Theoretical Chemistry
  • Materials Chemistry

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