Diphenylphosphino functionalization of mesoporous silica using tripodal linker units

Application of Tripodal Linker Units to Immobilized Diphenylphosphine Palladium Complex Catalysts for Suzuki-Miyaura Coupling Reactions of Aryl Bromide: Effect of Immobilization Method of Phosphine Ligand on Catalytic Performance

“…2(a). Two signals corresponding to one tetraalkyl-coordinated silicon (δ 2 ppm) and three trialkylmonooxygen-coordinated silicon atoms (δ 14 ppm) of 4(2) were observed in the 29 Si CP/MAS spectrum, suggesting that the tripodal anchoring structure of 2 was maintained even after the phosphine was attached 12), 13) . The 13 C CP/MAS spectrum exhibited several peaks, which corresponded to the carbon skeleton of 4(2).…”

“…The diphenylphosphino-functionalized mesoporous silicas 4(2) and 4(3) were prepared as described previously 13) . The diphenylphosphino-palladium complex catalysts were prepared by reacting diphenylphosphinofunctionalized silicas 4(2) and 4(3) with palladium acetate.…”

“…Diphenylphosphine Palladium Complex Catalyst The diphenylphosphino-functionalized ordered mesoporous silica 4(2) was prepared as described previously 13) : the tripodal linker unit containing a bromopropyl group was grafted and subsequently reacted with potassium diphenylphosphide (the "bottom-up" method). The organic content as determined by carbon elemental analysis and the textural properties as determined from the N2 adsorption/desorption isotherm of 4(2) are listed in Table 1.…”

“…1. Our previous study revealed that the "bottom-up" method results in the immobilization of PPh2 onto silica via the linker 13) . In contrast, the "top-down" method directly grafting the tripodal diphenyl phosphino ligands (3) suffers from PPh2 functionalization, probably because interaction of the phosphorous groups with the silica surface is preferred to reaction between the leaving groups and the silanol groups.…”

Immobilization of Molecular Catalysts on Silica <i>via</i> New Tripodal Linker Unit

“…9. The diphenylphosphino-functionalized silica 10a, which included the tripodal linker unit, was prepared by reaction of the 3-bromopropyl-functionalized silica (2b) with KPPh2 in THF as described previously ("bottomup" method) 20) . The trimethylsilyl-capped diphenylphosphino-functionalized silica 10b was prepared by capping the residual surface silanol groups of 2b with ethoxytrimethylsilane, followed by phosphination using K P P h2.…”