Palladium‐Loaded Cucurbit[7]uril‐Modified Iron Oxide Nanoparticles for C−C Cross‐Coupling Reactions

Abstract

Cucurbit[7]uril modified iron oxide nanoparticles (CB[7]NPs) were loaded with palladium to form nano-catalysts (Pd@CB[7]NPs) that, with microwave heating, catalysed Suzuki-Miyaura, Sonogashira, and Mizoroki-Heck cross-coupling reactions. Reactions were run in environmentally benign 1:1 ethanol/water solvent under convenient aerobic conditions. In a preliminary screening, conversions and yields were uniformly high with turn over frequencies (TOF) ranging from 64 to 7360 h . The nano-catalysts could be recovered with a magnet and reused several times (6 times for Suzuki-Miayura reaction) without loss of activity.

Nanopalladium on Magnetic Ionic Nanoparticle Network (MINN) as an Efficient and Recyclable Catalyst with High Ionic Density and Dispersibility

“…The Suzuki–Miyaura reaction is one of the most important C–C coupling reactions which lead to the synthesis of biaryl derivatives as key compounds in the production of fine chemicals, conducting polymers, herbicides, natural products, and pharmaceuticals. − This reaction has been traditionally accomplished in the presence of homogeneous palladium catalysts employing phosphine ligands − and N -heterocyclic carbenes − or palladacycle complexes. , However, most of these homogeneous systems suffer from several limitations such as difficulty in catalyst separation and recovery, requiring high catalyst loading, poisoning or deactivation of catalyst, and product contamination. To overcome these drawbacks, the immobilized catalysts have attracted particular attention, and various solid supports such as mesoporous and amorphous silica, − polymers, − zeolites, metal oxides, carbon material, − and magnetic nanoparticles or nanocomposites − have been applied for Pd-catalyzed Suzuki reaction. As mentioned earlier, the great challenge in the case of these systems is the capability of support to stabilize or recapture highly active and small Pd species during the course of reaction.…”

Recent Advances in Microwave‐assisted Cross‐Coupling Reactions

“…In 2018, Trabolsi & Guenin et al [46] prepared nano-catalysts (Pd@CB[7]NPs) from modified iron oxide nanoparticles(CB-[7]NPs) loaded with palladium and applied them on microwaveassisted Suzuki coupling reaction between aryl halide (13) and aryl boronic acid (14). The desired biarylated products (15) were achieved up to 98% yield (Scheme 30).…”

Recent Advances in Metal-Nanoparticle-Catalyzed Coupling Reactions Assisted by Microwave Irradiation

“…9 The reactions of aryl bromides proceeded in a short reaction time with a low amount of Pd/PVP (0.1 mmol ‰ Trabolsi and Guenin used palladium-loaded cucurbit [7]urilmodified iron oxide nanoparticles for cross-coupling reactions with microwave irradiation in 2018. 14 The Suzuki-Miyaura couplings and Sonogashira couplings of aryl iodides and aryl bromides proceeded smoothly to yield the corresponding products, while inert aryl chlorides were not employed in this catalytic system (Scheme 7 and 8). The Heck reaction of aryl iodide using Pd/CB [7]NP catalyst also proceeded with good product yield, but moderate conversion was observed with aryl bromide (Scheme 9).…”