Development of Pd supported catalysts using thiol-functionalized mesoporous silica frameworks: application to the chemo-and regio-selective C-3 arylation of free-indole - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue European Journal of Inorganic Chemistry Année : 2021

Development of Pd supported catalysts using thiol-functionalized mesoporous silica frameworks: application to the chemo-and regio-selective C-3 arylation of free-indole

Résumé

We report here the development of Pd-supported catalysts for the selective C-3 arylation of free-indole using thiol-functionalized silica supports to anchor the palladium centers. The palladium (II) complex, Pd(OAc)2, was efficiently loaded into various thiol-functionalized mesostructured silicas at room temperature. These materials exhibit different contents of surface SH groups (0.3 to 1.8 SH/nm2) and various SH/Pd molar ratios from 6 to 65. It was found that the catalysts containing the most isolated surface SH groups (0.3 SH/nm2) and the highest loading of Pd were the most active, reaching 70% of conversion, 1400 as turnover numbers and 100% selectivity in the C-3 arylated product using only 0.05 mol% of Pd. However, a leaching of active Pd species (1.7 ppm) was detected. The best compromise was found for a specific solid containing isolated surface thiol groups (0.3 SH/nm2) and a very low loading of Pd (SH/Pd = 65). It exhibited a high TON (608) with a very low Pd leaching of 0.5 ppm in the course of the catalytic reaction. These results thus illustrate that both surface SH site isolation and concentration, as well as the SH/Pd ratio are key parameters to access high catalytic performances and very low leaching of metal during catalysis.

Domaines

Catalyse Chimie
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Dates et versions

hal-03805125 , version 1 (07-10-2022)

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Marc Renom Carrasco, Walid Khodja, Clément Demarcy, Laurent Veyre, Clément Camp, et al.. Development of Pd supported catalysts using thiol-functionalized mesoporous silica frameworks: application to the chemo-and regio-selective C-3 arylation of free-indole. European Journal of Inorganic Chemistry, 2021, ⟨10.1002/ejic.202001086⟩. ⟨hal-03805125⟩
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