Mechanism of Alkyne Alkoxycarbonylation at a Pd Catalyst with P,N Hemilabile Ligands: A Density Functional Study
| Autor: | David J. Cole-Hamilton, Eite Drent, Michael Bühl, Luke Crawford |
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| Přispěvatelé: | University of St Andrews. School of Chemistry, University of St Andrews. EaSTCHEM |
| Rok vydání: | 2014 |
| Předmět: |
Reaction mechanisms
Alkyne chemistry.chemical_element Carbonylation Homogeneous catalysis Propyne Photochemistry Catalysis chemistry.chemical_compound Computational chemistry Palladium complexes QD chemistry.chemical_classification Ligand Organic Chemistry Solvation Exchange Esters General Chemistry QD Chemistry Density functional calculations chemistry Alkynes Density functional theory BDC Palladium Model |
| Zdroj: | Chemistry – A European Journal. 20:13923-13926 |
| ISSN: | 1521-3765 0947-6539 |
| Popis: | The authors thank the School of Chemistry and EaStCHEM for support. 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. Postprint |
| Databáze: | OpenAIRE |
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