The Pd(0) and Pd(II) SBA-TU-anchored catalysts in the Mizoroki-Heck and Suzuki-Miyaura cross-coupling reactions: A comparative catalytic study

The surface of the mesoporous silica SBA-15 (SBA) was modified by a tetra-urea (TU) ligand (SBA@TU), and the palladium ions were anchored within the multidentate pore channels (SBA@TU@Pd(II)) and re-duced by NaBH4 (SBA@TU@Pd(0)). Then, the nano-structure reduced catalyst was characterized by FT-IR, EDX, elemental mapping analysis, XRD, SEM, TEM, TGA/DTA/DCS, and BET analysis. After that, the catalytic activity of the SBA@TU @Pd(0) catalyst was successfully studied in the Mizoroki-Heck and Suzuki-Miyaura cross-coupling reactions under mild reaction conditions for preparation of 1(a-l) and 2(a-i), respectively in short reaction times and high yields. Also, the Mizoroki-Heck and Suzuki-Miyaura cross-coupling re-actions were performed by the non-reduced nano-catalyst (SBA@TU@Pd(II)) under similar reaction con-ditions. The reaction yields were the same for both catalysts, but the reaction time was different which was shorter (30 min) for SBA@TU@Pd(0), while for SBA@TU@Pd(II) the reaction times were increased to about 80 and 70 min, respectively.(c) 2022 Elsevier B.V. All rights reserved.