Development of Pd Supported Catalysts Using Thiol‐Functionalized Mesoporous Silica Frameworks: Application to the Chemo‐ and Regioselective <i>C</i> ‐3 Arylation of Free‐Indole

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