Dimethylformamide-stabilised palladium nanoclusters catalysed coupling reactions of aryl halides with hydrosilanes/disilanes

Deconvoluting Substrates, Support, and Temperature Effects on Leaching and Deactivation of Pd Catalysts: An In Situ Study in Flow

Leaching behavior of three different Pd heterogeneous catalysts (PdEnCat 30, FibreCat FC1001, and Pd/Al2O3) during the Heck reaction of iodobenzene and methyl acrylate, in the presence of triethylamine, was compared using a tandem flow reactor. While leaching was observed in all three cases, Pd/Al2O3 appeared to be the most robust, showing little/no leaching at ambient temperature. The leached Pd species also appear to display different catalytic activities. With a slight modification of the reactor, the leaching caused by individual components of the reaction mixture can be assessed separately. For the polymer-supported catalysts, triethylamine caused the largest amount of leaching, even at 30 °C. In contrast, the leaching from Pd/Al2O3 was observed only in the presence of iodobenzene at 90 °C. Variations in leaching behavior were ascribed to differences in Pd species and immobilization methods.

Direct synthesis and applications of solid silylzinc reagents

The increased synthetic utility of organosilanes has motivated researchers to develop milder and more practical synthetic methods. Silylzinc reagents, which are typically the most functional group tolerant, are notoriously difficult to synthesize because they are obtained by a pyrophoric reaction of silyllithium, particularly Me3SiLi which is itself prepared by the reaction of MeLi and disilane. Furthermore, the dissolved LiCl in silylzinc may have a detrimental effect. A synthetic method that can avoid silyllithium and involves a direct synthesis of silylzinc reagents from silyl halides is arguably the simplest and most economical strategy. We describe, for the first time, the direct synthesis of PhMe2SiZnI and Me3SiZnI reagents by employing a coordinating TMEDA ligand, as well as single crystal XRD structures. Importantly, they can be obtained as solids and stored for longer periods at 4 °C. We also demonstrate their significance in cross-coupling of various free alkyl/aryl/alkenyl carboxylic acids with broader functional group tolerance and API derivatives. The general applicability and efficiency of solid Me3SiZnI are shown in a wide variety of reactions including alkylation, arylation, allylation, 1,4-addition, acylation and more.

N,N-Dimethylformamide-stabilised palladium nanoparticles combined with bathophenanthroline as catalyst for transfer vinylation of alcohols from vinyl ether

We report N,N-dimethylformamide-stabilised Pd nanoparticle (Pd NP)-catalysed transfer vinylation of alcohols from vinyl ether. Pd NPs combined with bathophenanthroline exhibited high catalytic activity. This reaction proceeded with low catalyst loading and the catalyst remained effective even after many rounds of recycling. The observation of the catalyst using transmission electron microscopy and dynamic light scattering implied no deleterious aggregation of Pd NPs.

Cross β-alkylation of primary alcohols catalysed by DMF-stabilized iridium nanoparticles

A simple method for the cross β-alkylation of linear alcohols with benzyl alcohols in the presence of DMF-stabilized iridium nanoparticles was developed. The nanoparticles were prepared in one-step and thoroughly characterized. Furthermore, the optimum reaction conditions have a wide substrate scope and excellent product selectivity.

Synthesis and Characterization of N,N-Dimethylformamide-Protected Palladium Nanoparticles and Their Use in the Suzuki-Miyaura Cross-Coupling Reaction

Herein, the synthesis of new N,N-dimethylformamide (DMF)-protected palladium nanoparticles (Pd NPs-OAc) employing Pd (OAc)2 (= Pd(OCOCH3)2) as the NP precursor is reported. Pd NPs-OAc were comprehensively characterized by transmission electron microscopy, FT-IR, NMR, and X-ray photoelectron spectroscopy to determine the Pd NP size distribution and the coordination state of DMF. Pd NPs-OAc were compared with Pd NPs-Cl, using PdCl2 as the NP precursor. The Suzuki-Miyaura cross-coupling reaction proceeded efficiently in the presence of Pd NPs-OAc and a high catalytic activity was observed with a turnover number of up to 1.5 × 105. Furthermore, the Pd NP-OAc catalysts could be recycled at least five times.

N,N-Dimethylformamide-Protected Single-Sized Metal Nanoparticles and Their Use as Catalysts for Organic Transformations

In this mini-review, we summarize the solution syntheses of N,N-dimethylformamide (DMF)-protected metal nanoparticles (NPs) and nanoclusters (NCs) and their use in catalytic reactions. Representative examples are given of external-stabilizer/protectant-free metal NP and NC syntheses by reduction with DMF. In this method, DMF has three roles, i.e., a solvent, reductant, and protectant. Recent applications of DMF-stabilized metal NPs are summarized. These applications have enabled a versatile organic transformation such as cross-coupling reactions, hydrosilylation, and methylation to be achieved. These reactions proceed under low catalyst loadings and ligandless conditions.