Methoxycarbonylation of olefins catalyzed by palladium complexes bearing P,N-donor ligands

Aguirre, PA; Lagos, CA; Moya, SA; Zuñiga E; Vera-Oyarce, C; Sola, E.; Peris, G; Bayon, JC

Abstract

The methoxycarbonylation of alkenes catalyzed by palladium(ii) complexes with P,N-donor ligands, 2-(diphenylphosphinoamino)pyridine (Ph 2PNHpy), 2-[(diphenylphosphino)methyl]pyridine (Ph 2PCH 2py), and 2-(diphenylphosphino)quinoline (Ph 2Pqn) has been investigated. The results show that the complex [PdCl(PPh 3)(Ph 2PNHpy)]Cl or an equimolar mixture of [PdCl 2(Ph 2PNHpy)] and PPh 3, in the presence of p-toluensulfonic acid (TsOH), is an efficient catalyst for this reaction. This catalytic system promotes the conversion of styrene into methyl 2-phenylpropanoate and methyl 3-phenylpropanoate with nearly complete chemoselectivity, 98% regioselectivity in the branched isomer, and high turnover frequency, even at alkene/Pd molar ratios of 1000. Best results were obtained in toluene-MeOH (3: 1) solvent. The Pd/Ph 2PNHpy catalyst is also efficient in the methoxycarbonylation of cyclohexene and 1-hexene, although with lower rates than with styrene. Related palladium complexes [PdCl(PPh 3)L]Cl (L = Ph 2PCH 2py and Ph 2Pqn) show lower activity in the methoxycarbonylation of styrene than that of the 2-(diphenylphosphinoamino)pyridine ligand. Replacement of the last ligand by (diphenylphosphino)phenylamine (Ph 2PNHPh) or 2- (diphenylphosphinoaminomethyl)pyridine (Ph 2PNMepy) also reduces significantly the activity of the catalyst, indicating that both the presence of the pyridine fragment as well as the NH group, are required to achieve a high performing catalyst. Isotopic labeling experiments using MeOD are consistent with a hydride mechanism for the [PdCl(PPh 3)(Ph 2PNHpy)]Cl catalyst. © The Royal Society of Chemistry.

Más información

Título según WOS: Methoxycarbonylation of olefins catalyzed by palladium complexes bearing P,N-donor ligands
Título según SCOPUS: Methoxycarbonylation of olefins catalyzed by palladium complexes bearing P,N-donor ligands
Título de la Revista: DALTON TRANSACTIONS
Número: 46
Editorial: ROYAL SOC CHEMISTRY
Fecha de publicación: 2007
Página de inicio: 5419
Página final: 5426
Idioma: English
URL: http://xlink.rsc.org/?DOI=b704615b
DOI:

10.1039/b704615b

Notas: ISI, SCOPUS