Mechanism of alkyne alkoxycarbonylation at a Pd catalyst with P,N hemilabile ligands: a density functional study

Luke Crawford, David J. Cole-Hamilton, Eite Drent, Michael Buehl*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

59 Citations (Scopus)
14 Downloads (Pure)

Abstract

A detailed mechanism for alkyne alkoxycarbonylation mediated by a palladium catalyst has been characterised at the B3PW91-D3/PCM level of density functional theory (including bulk solvation and dispersion corrections). This transformation, investigated via the methoxycarbonylation of propyne, involves a uniquely dual role for the P, N hemilabile ligand acting co-catalytically as both an in situ base and proton relay coupled with a Pd0 centre, allowing for surmountable barriers (highest ΔG of 22.9 kcal mol-1 for alcoholysis). This proton-shuffle between methanol and coordinated propyne accounts for experimental requirements (high acid concentration) and reproduces observed regioselectivities as a function of ligand structure. A simple ligand modification is proposed, which is predicted to improve catalytic turnover by three orders of magnitude.

Original languageEnglish
Pages (from-to)13923-13926
Number of pages4
JournalChemistry - A European Journal
Volume20
Issue number43
Early online date5 Sept 2014
DOIs
Publication statusPublished - 10 Oct 2014

Keywords

  • Alkynes
  • Density functional calculations
  • Homogeneous catalysis
  • Palladium
  • Reaction mechanisms
  • Palladium complexes
  • Carbonylation
  • Exchange
  • Esters
  • Model

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