Towards the rational design of palladium-N-heterocyclic carbene catalysts by a combined experimental and computational approach

Autor:	Alan C. Hopkinson, Ting-Hua Tang, Niloufar Hadei, Eric Assen B. Kantchev, Christopher J. O'Brien, De-Cai Fang, Michael G. Organ, Gregory A. Chass, David H. Setiadi
Rok vydání:	2005
Předmět:	Steric effects Negishi coupling Ligand Stereochemistry Organic Chemistry chemistry.chemical_element Biochemistry Oxidative addition PEPPSI chemistry.chemical_compound chemistry Suzuki reaction Computational chemistry Drug Discovery Carbene Palladium
Zdroj:	Tetrahedron. 61:9723-9735
ISSN:	0040-4020
DOI:	10.1016/j.tet.2005.07.101
Popis:	A combined experimental and computational approach towards the development of Pd–NHC catalysts is described. A range of benzimidazolylidinium ligands incorporating electron-rich and electron-poor substituents were prepared and evaluated in the Suzuki reaction. The most electron-rich ligand showed the highest catalytic activity. Based on this information, the first alkyl–alkyl Negishi cross-coupling reaction protocol was developed. Evaluation of N,N′-diaryl-(4,5-dihydro)imidazolylilidinium ligands showed a strong dependence on the steric topography around the metal centre. A computational study of the most active ligand in the Negishi reaction, its Pd(0) and PdCl2-complexes and related structures were modelled at the B3LYP/DZVP and HF/3-21G levels of theory. The potential energy hypersurfaces flattened with increase in ligand size. Binding energies were computed for carbene/Pd(0) adducts (in the range ∼31–40 kcal mol−1), roughly double that for PH3 (∼16 kcal mol−1). Weak intramolecular interactions were found using AIM analyses.
Databáze:	OpenAIRE
Externí odkaz:	https://explore.openaire.eu/search/publication?articleId=doi_________::9e167e0557fb8afd0be5a2c41c2a78c2 https://doi.org/10.1016/j.tet.2005.07.101 Zobrazit plný text záznamu Full Text from ScienceDirect