Suzuki-Miyaura reactions promoted by a PdCl2 /sulfonate-tagged phenanthroline precatalyst in water

Highly active small Pd nanocatalysts obtained by visible-light-induced photoreduction with citrate and oxalate salts under batch and flow approaches

With a suitable combination of citrate and oxalate salts as photoinitiators, a visible-light induced Pd NP synthesis was conducted. Depending on the reaction conditions of the catalysis, the ligands may have a great impact on the catalytic activity.

Visible-Light-Enhanced Suzuki-Miyaura Reactions of Aryl Chlorides in Water with Pd NPs Supported on a Conjugated Nanoporous Polycarbazole

The visible-light-enhanced catalytic activation of aryl chlorides for Suzuki-Miyaura cross-coupling (SMC) reactions is highly challenging because of the strength of the C-Cl bond. In this work, palladium nanoparticles (Pd NPs) were grown on a conjugated nanoporous polycarbazole (CNP), named Pd/CNP. The hybrid material Pd/CNP could catalyze the SMC reactions of aryl chlorides with arylboronic acids in water under blue LED irradiation at room temperature with high efficiency. This protocol exhibited good functional group tolerance and the catalyst could be recycled without significant loss of its catalytic activity. CNP not only provided photogenerated electrons to enrich the electron density of the Pd NPs but also generated holes for the activation of the arylboronic acids.

Study of the dual functional behaviour of 1,2-bis(4-bromobenzamide)benzene by synchronous fluorescence spectroscopy

This study presents the dual functionality of 1,2-bis(4-bromobenzamide)benzene, where depending on the stoichiometric conditions, temperature and reaction time, the compound may act as a PdCl₂ ligand or as one of the reactants of the Suzuki coupling reaction.

Bedford-Type Palladacycle-Catalyzed Miyaura Borylation of Aryl Halides with Tetrahydroxydiboron in Water

A mild aqueous protocol for palladium catalyzed Miyaura borylation of aryl iodides, aryl bromides and aryl chlorides with tetrahydroxydiboron (BBA) as a borylating agent is developed. The developed methodology requires low catalyst loading of Bedford-type palladacycle catalyst (0.05 mol %) and works best under mild reaction conditions at 40 °C in short time of 6 h in water. In addition, our studies show that for Miyaura borylation using BBA in aqueous condition, maintaining a neutral reaction pH is very important for reproducibility and higher yields of corresponding borylated products. Moreover, our protocol is applicable for a broad range of aryl halides, corresponding borylated products are obtained in excellent yields up to 93% with 29 examples demonstrating its broad utility and functional group tolerance.

Palladium(ii) and palladium(ii)-silver(i) complexes with N-heterocyclic carbene and zwitterionic thiolate mixed ligands: synthesis, structural characterization and catalytic properties

The integration of a geometrically rigid Pd(ii), a coordinatively monotonous N-heterocyclic carbene 1,3-dimethylimidazoline-2-ylidene (IMe), and a flexible zwitterionic thiolate 4-(trimethylammonio)benzenethiolate (Tab) affords a class of Pd-IMe-Tab complexes with various nuclearities, namely, trans-[Pd(IMe)₂(Tab)₂](OTf)₂ (2, mononuclear), cis-[Pd(IMe)₂(Tab)₂](OTf)(Cl) (3a, mononuclear), cis-[Pd(IMe)₂(Tab)₂](PF₆)₂·MeCN (3b·MeCN, mononuclear), [Pd₂(IMe)₄(Tab)₂](PF₆)₄·2MeCN (4·2MeCN, dinuclear) and [Pd₄(IMe)₄(Tab)₆](OTf)₆(Cl)₂ (5, tetranuclear). Further presence of Ag(i) in the assembly provides a heterometallic octanuclear cluster of [Pd₄Ag₄(IMe)₈(Tab)₁₀](PF₆)₁₂ (6). Compounds 2-6 are formed by the reaction of trans-Pd(IMe)₂Cl₂ (1) with various additional reagents via different reaction pathways. These compounds are characterized by means of FT-IR, ¹H and ¹³C NMR, ESI-MS, elemental analysis and X-ray crystallography. Notably, the skeleton of compound 5 features a [Pd₄S₄] parallelogram wherein each of the four Pd(ii) centers bisects the edge defined by the S atoms. The main skeleton of compound 6 is an oval-shaped Pd₄Ag₄S₁₀ unit, featuring an edge-fused norbornane-like (Pd₂Ag₄S₆) framework appended by two additional PdS₂ motifs at the polar positions. Compounds 5 and 6 also feature PdPd (5), PdAg and AgAg (6) interactions. Compound 5 as a representative example is highly effective at catalyzing Suzuki-Miyaura couplings in water, highlighting the potential of applying these types of homo- and heterometallic clusters as catalysts for organic transformations in environmentally benign media.

Catalytic Organic Reactions in Water toward Sustainable Society

Traditional organic synthesis relies heavily on organic solvents for a multitude of tasks, including dissolving the components and facilitating chemical reactions, because many reagents and reactive species are incompatible or immiscible with water. Given that they are used in vast quantities as compared to reactants, solvents have been the focus of environmental concerns. Along with reducing the environmental impact of organic synthesis, the use of water as a reaction medium also benefits chemical processes by simplifying operations, allowing mild reaction conditions, and sometimes delivering unforeseen reactivities and selectivities. After the "watershed" in organic synthesis revealed the importance of water, the development of water-compatible catalysts has flourished, triggering a quantum leap in water-centered organic synthesis. Given that organic compounds are typically practically insoluble in water, simple extractive workup can readily separate a water-soluble homogeneous catalyst as an aqueous solution from a product that is soluble in organic solvents. In contrast, the use of heterogeneous catalysts facilitates catalyst recycling by allowing simple centrifugation and filtration methods to be used. This Review addresses advances over the past decade in catalytic reactions using water as a reaction medium.

Efficient symmetrical bidentate dioxime ligand-accelerated homogeneous palladium-catalyzed Suzuki–Miyaura coupling reactions of aryl chlorides

A series of N,O-bidentate ligands were synthesized and studied as high activity ligands for palladium-catalyzed Suzuki–Miyaura cross-coupling reactions of aryl chlorides with arylboronic acids under mild conditions.

Dual functionalized task specific ionic liquid promoted in situ generation of palladium nanoparticles in water: synergic catalytic system for Suzuki–Miyaura cross coupling

A new task specific ionic liquid with hydroxyl and prolinate functionalities acts as a reducing agent and serves as a ligand and stabilizer for in situ formed palladium nanoparticles. This system displays high catalytic activity for Suzuki–Miyaura cross-coupling in water.