s, or keywords if they used Heck-type chemistry in their syntheses, because it became one of basic tools of organic preparations, a natural way to

http://aether.cmi.ua.ac.be/artikels/Artikels%20Gitte/Artikels/Reviews/Heck%20reactie%20Beletskaya%20%20Chem.%20Rev.%20003009.pdf

The heck reaction as a sharpening stone of palladium catalysis.

Interest in catalysis by metal nanoparticles (NPs) is increasing dramatically, as reflected by the large number of publications in the last five years. This field, "semi-heterogeneous catalysis", is at the frontier between homogeneous and heterogeneous catalysis, and progress has been made in the efficiency and selectivity of reactions and recovery and recyclability of the catalytic materials. Usually NP catalysts are prepared from a metal salt, a reducing agent, and a stabilizer and are supported on an oxide, charcoal, or a zeolite. Besides the polymers and oxides that used to be employed as standard, innovative stabilizers, media, and supports have appeared, such as dendrimers, specific ligands, ionic liquids, surfactants, membranes, carbon nanotubes, and a variety of oxides. Ligand-free procedures have provided remarkable results with extremely low metal loading. The Review presents the recent developments and the use of NP catalysis in organic synthesis, for example, in hydrogenation and C--C coupling reactions, and the heterogeneous oxidation of CO on gold NPs.

Nanoparticles as Recyclable Catalysts: The Frontier between Homogeneous and Heterogeneous Catalysis

4.4. Pd on Modified Silica 159 4.5. Pd on Clay and Other Inorganic Materials 159 5. Stille, Fukuyama, and Negishi Reactions 159 5.1. Stille Reactions 159 5.1.1. Pd on Carbon (Pd/C) 159 5.1.2. Palladium on KF/Al2O3 159 5.1.3. Pd on Modified Silica (SiO2/TEG/Pd) 159 5.2. Fukuyama Reactions 159 5.2.1. Pd on Carbon (Pd/C) 159 5.2.2. Pd(OH)2 on Carbon (Perlman’s Catalyst) 160 5.3. Pd/C-Catalyzed Negishi Reactions 160 6. Ullmann-Type Coupling Reactions 161 6.1. Pd/C-Catalyzed Aryl−Aryl Coupling 161 6.2. Pd/C-Catalyzed Homocoupling of Vinyl Halides 162

https://www.chem.ccu.edu.tw/~joyce/referance/ericyang/Chem.%20Rev/Chem.%20Rev.%202007,%20107,%20133-173.pdf

Carbon-Carbon Coupling Reactions Catalyzed by Heterogeneous Palladium Catalysts

A wide array of forms of palladium has been utilized as precatalysts for Heck and Suzuki coupling reactions over the last 15 years. Historically, nearly every form of palladium used has been described as the active catalytic species. However, recent research has begun to shed light on the in situ transformations that many palladium precatalysts undergo during and before the catalytic reaction, and there are now many suggestions in the literature that narrow the scope of types of palladium that may be considered true “catalysts” in these coupling reactions. In this work, for each type of precatalyst, the recent literature is summarized and the type(s) of palladium that are proposed to be truly active are enumerated. All forms of palladium, including discrete soluble palladium complexes, solid-supported metal ligand complexes, supported palladium nano- and macroparticles, soluble palladium nanoparticles, soluble ligand-free palladium, and palladium-exchanged oxides are considered and reviewed here. A considerable focus is placed on solid precatalysts and on evidence for and against catalysis by solid surfaces vs. soluble species when starting with various precatalysts. The review closes with a critical overview of various control experiments or tests that have been used by authors to assess the homogeneity or heterogeneity of catalyst systems.

On the Nature of the Active Species in Palladium Catalyzed Mizoroki–Heck and Suzuki–Miyaura Couplings – Homogeneous or Heterogeneous Catalysis, A Critical Review

Pd2+-exchanged graphite oxide and chemically derived graphenes therefrom were employed as supports for Pd nanoparticles. The influence of catalyst preparation, carbon functionalization, and catalyst morphology on the catalytic activity in the Suzuki−Miyaura coupling reactions was investigated. The catalysts were characterized by means of spectroscopy (FT-IR, solid-state 13C NMR, AAS, XPS), X-ray scattering (WAXS), surface area analysis (BET, methylene blue adsorption), and electron microscopy (TEM, ESEM). In contrast to the conventional Pd/C catalyst, graphite oxide and graphene-based catalysts gave much higher activities with turnover frequencies exceeding 39 000 h−1, accompanied by very low palladium leaching (<1 ppm).

Palladium Nanoparticles on Graphite Oxide and Its Functionalized Graphene Derivatives as Highly Active Catalysts for the Suzuki−Miyaura Coupling Reaction

[Pd]-exchanged NaY zeolites have been prepared, characterized, and applied for the first time for catalytic carbon-carbon coupling reactions. The catalysts exhibit a high activity and selectivity toward the Heck reaction of aryl bromides with olefins for small palladium concentrations (< or =0.1 mol % of Pd). The catalysts can easily be separated from the reaction mixture and reused after washing without loss in activity. No limitation to the diffusion of adducts in the zeolite cages was observed (for linear alkenes). The electronic nature of the aryl bromides and the olefins has a dominating effect on the reaction yield and selectivity. The heterogeneous catalysts quantitatively convert all types of all aryl bromide (complete conversion of bromobenzene within 30 min) and activated aryl chlorides under standard reaction conditions. Product form selectivity is observed in the Heck reaction with cyclic olefins.

Heck reaction catalyzed by PD-modified zeolites.

Supported palladium as catalyst for carbon–carbon bond construction (Heck reaction) in organic synthesis

Palladium modified zeolites exhibit a high activity towards the Heck reaction of aryl bromides with styrene for small Pd concentrations (=0.2 mol%). The catalysts can be easily separated from the reaction mixture and reused without loss in activity. Leaching of active Pd species was observed in dependence on the zeolite structure. The electronic nature of the aryl bromide has a dominating effect on the reaction yield and the results observed are consistent with an oxidative addition of the aryl bromide to a Pd(0) centre via a S N Ar route.

Heterogeneously catalysed Heck reaction using palladium modified zeolites

The catalytic activity and selectivity of palladium supported on various metal oxides in carbon–carbon coupling reactions of aryl bromides with styrene (Heck reaction) were investigated. The activity is determined by the nature of the oxide support and the Pd dispersion (structure–activity relationships). The relation of homogeneous (leaching) and heterogeneous mechanisms is discussed.

Laurent Djakovitch

Papers

Heck reaction catalyzed by PD-modified zeolites.

Supported palladium as catalyst for carbon–carbon bond construction (Heck reaction) in organic synthesis

Heterogeneously catalysed Heck reaction using palladium modified zeolites

Heck reactions catalyzed by oxide-supported palladium – structure–activity relationships

Heck reactions between aryl halides and olefins catalysed by Pd-complexes entrapped into zeolites NaY