Search

α-Alkylation reactions between amides and alcohols, with dimethylacetamide-stabilized Ru nanoparticles (NPs) as the catalyst, were investigated. The reactions proceeded with low catalyst loadings compared to metal complexes. Characterizations of the Ru NPs were performed by X-ray photoelectron spectroscopy, X-ray absorption fine structure spectroscopy, and various techniques. Control experiments revealed the reaction mechanisms, which proceeded

To enhance the hydrodesulfurization (HDS) activity of SiO2-supported Rh phosphide catalysts, various second metal-added Rh–P catalysts were developed; furthermore, the effect of the addition of the second metal on the HDS performance was examined. The second metals (M: Ru, Pt, and Ir) were selected as per the Sabatier principle. In situ X-ray diffraction revealed the formation of an Rh2P phase in the Rh–M–P catalyst after reduction. The addition of Ru and Pt to the Rh–P catalyst enhanced the C−S bond cleavage activity, whereas the addition of Ir had virtually no effect. The Rh–Pt–P catalyst demonstrated the highest HDS activity among Rh–M–P catalysts. The characterization results revealed the presence of positively charged Pt on the Rh–Pt–P catalyst surface, in which Pt and Rh cooperatively act as active sites to enhance the C−S bond cleavage activity.

N,N-Dimethylformamide-stabilized Ru nanoparticles (NPs) provide a highly efficient catalyst for the Guerbet reaction of primary alcohols under solvent-free conditions and without the use of external ligands.

A regioselective and Z-selective three-component silylalkoxylation of 1,3-diene using various alcohols, disilane, and a catalytic Pd/Cu/1,4-benzoquinone/O2 system is established in this Letter. The reaction generates tetra-substituted allyl silanes containing allyl ether moieties in up to 80% isolated yield and on a 1-10 mmol scale via oxidative coupling. A wide variety of substrates, including benzyl alcohol derivates, aliphatic alcohols, and bioactive compounds such as cholesterol, are suitable for use in the developed reaction system.

The first successful example of a catalytic enantioselective intramolecular Tishchenko reaction of a meso-dialdehyde in the presence of a chiral iridium complex is described. Chiral lactones were obtained in good yields with up to 91% ee. The obtained enantioenriched lactones were utilized for the first synthesis of (S)-cedarmycins A and B.

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.

Ti-Pd alloy catalysts were developed for the cross β-arylmethylation between arylmethylalcohols and different primary alcohols via a hydrogen autotransfer mechanism. The alloy catalysts could be reused multiple times without the need for pre-activation. Analysis of the reaction solution by inductively coupled plasma atomic absorption spectroscopy indicated that only a minimal amount of Ti and no Pd was leached from the catalyst.

Copper nanoparticles fabricated onto reduced graphene oxide (Cu NPs/rGO) were successfully synthesized via a one-pot dimethylformamide (DMF) reduction approach with an addition of nominal water. Th...

Effect of P/Rh ratio and reduction temperature on catalytic activity and product selectivity of rhodium phosphide (Rh2P) for hydrodeoxygenation (HDO) of phenol was studied to develop production of ...

Ti–Pd alloys have been found to be novel heterogeneous palladium catalysts for organic cross-coupling reactions. Catalyst preactivation is not necessary, resulting in facile recovery and reuse of t...

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.

A highly regioselective and stereoselective difunctionalization reaction of 1,3-diene with amine and disilane to form C-N and C-Si bonds via a one-step Pd/Cu/O2 system is disclosed. The difunctionalization reaction affords allylic silanes, including the allylic amine moiety, in up to 92 % yield in the absence of any acid, base, or external ligand. The developed synthetic methodology can be scaled to 100 g in high yield with high Z-selectivity, which demonstrates the feasibility of the reaction for industrial applications.

The development of a C2-extension of primary alcohols with ethanol as the C2 source and catalysis by [Cp*IrCl2]2 (where Cp* = pentamethylcyclopentadiene) is described. This new extension system was used for a range of benzylic alcohol substrates and for aliphatic alcohols with ethanol as an alkyl reagent to generate the corresponding C2-extended linear alcohols. Mechanistic studies of the reaction by means of intermediates and deuterium labeling experiments suggest the reaction is based on hydrogen autotransfer.

N,N-Dimethylformamide-stabilised Pd nanocluster (NC) catalysed cross-coupling reactions of hydrosilane/disilane have been investigated. In this reaction, the coupling reaction proceeds without ligands with low catalyst loading. N,N-Dimethylacetamide is a crucial solvent in these reactions. The solvent effect was considered by various techniques, such as transmission electron microscopy, X-ray photoelectron spectroscopy, and thermogravimetric analysis. The Pd NCs can be recycled five times under both hydrosilane and disilane reaction conditions.

Au25(SC2H4Ph)18 nanoclusters have high catalytic activity for hydroamination of terminal alkynes. This reaction proceeds under O2 or air. The presence of molecular oxygen has a profound effect on the Au25(SC2H4Ph)18 reactivity. The catalysts can be separated from the mixture after the reaction and reused.

An active in situ-generated Nb complex was used as a catalyst in the ring-closing metathesis reaction of N,N-diallyl-p-toluenesulfonamide to afford the corresponding 3-pyrroline derivative. The Nb complex was formed from NbCl5, trimethylsilyl chloride, Zn, and PhCHCl2 in tetrahydrofuran. The Nb complex displayed high catalytic activity toward ring-closing metathesis reactions.

N-Alkenyl carbazoles are important building blocks of poly(vinylcarbazole), which is used in photosensitive materials, semiconductors, electroluminescent devices, and non-linear optical materials. Recently, a C N bond formation reaction using transition-metal-catalyzed amination and transition-metal-catalyzed vinylation was successfully extended to the synthesis of N-alkenyl carbazoles. In this paper, I discuss recent examples of the synthesis of N-alkenyl carbazoles, including palladium and copper-catalyzed cross-coupling reactions of carbazoles with alkenes/alkenyl halides, and iridium-catalyzed vinylation of carbazole using vinyl acetate.

We show that N,N-dimethylformamide-stabilized Pd nanoclusters (NCs) have high catalytic activity in the reaction of substituted 2-iodoanilines with alkynes to give 2,3-disubstituted indoles. This indole synthesis does not require phosphine ligands and proceeds with low Pd catalyst loadings. The Pd NCs were separated from the mixture after the reaction, and recycled at least three times. Transmission electron microscopy images showed that the Pd particle size before the reaction was 1.5–2.5 nm. The particle size after the reaction was 2–3 nm. X-ray photoelectron spectroscopy showed that the binding energy of the Pd NCs before the reaction was 335.0 eV.

NbCl5-catalyzed [2 + 2 + 2] cycloaddition of nitriles with alkynes was used to synthesize pyrimidine derivatives. In this reaction, the use of individual Lewis acids, namely NbCl5 and FeCl3, is a key strategy for achieving the reaction using a catalytic amount of NbCl5. The roles of the two Lewis acids were investigated using FT-IR spectroscopy. The results showed that NbCl5 served as an efficient Lewis acid catalyst for nitrile activation, whereas FeCl3 showed stronger Lewis acidity toward pyrimidines, releasing NbCl5 into the catalytic cycle.

A NbCl5, Zn, and PCy3 catalytic system that generated low-valent Nb species is used for the synthesis of bicyclic cyclohexadienes from diynes and simple alkenes. A phosphine ligand is important for stabilizing low-valent Nb in the cycloaddition. The bicyclic cyclohexadiene skeleton is important in transition-metal-catalyzed intramolecular cycloadditions.

IrCl(cod)2]/dppe-catalyzed α-methylation of aryl esters using methanol as the C1 source was developed. This methylation process is useful in several fields including organic chemistry, biochemistry, and medicinal chemistry. Readily available methanol as methylation reagent was successfully adapted. The reaction processed high atom economy and efficient. By applying the reaction system, the synthesis method of naproxen was provided.

We report a practical method for the synthesis of vinylcarbazoles via iridium-catalyzed vinylation of carbazoles with vinyl acetate as the vinyl source. This simple and efficient reaction using an iridium catalyst provides a convenient method for producing monomers for the synthesis of poly( N -vinylcarbazole)s, which are used in electroluminescent devices.

We report the catalysis of a Sonogashira–Hagihara cross-coupling reaction using a DMF-stabilized copper nanoparticle catalyst. The reaction proceeded with low catalyst loadings, and a turnover number of 4.0 × 103 was recorded for 0.01 mol% catalyst loading. DMF-stabilized copper nanoparticles thus showed high catalytic activity.

Niobium complexes in organic reactions have received a lot of attention in recent years. Niobium is one of the early transition metals, which possess unique reactivity distinct from that of other transition metals. This review focuses mainly on stoichiometric reactions and catalytic reactions involving niobium complexes. In particular, recent results relating to NbV-mediated or NbIII-catalyzed [2+2+2] cycloaddition of unsaturated compounds (alkyne, alkenes, nitriles, and isocyanates) are mainly presented in this review. In one example of a set of catalytic reactions involving a low-valent niobium species, the reaction between NbCl5 and tris(trimethylsilyl)silane generated a low-valent niobium(III) species, and this promoted [2+2+2] cycloaddition of terminal alkynes and olefins to provide cyclohexa-1,3-dienes. In addition, the use of low-valent niobium(III) species in stoichiometric reactions has also been reported. Many of these reactions are carried out by formation of Nb–alkyne complexes through reactions between low-valent niobium(III) and internal alkynes. Some examples of the use of Nb complexes as Lewis acids have also been reported. In these reactions, the valence of the Nb complexes is V.

In this study, we report a thiolate-protected Au nanocluster, Au25(phenylethanethiol)18 [Au25(PET)18], which serves as an efficient catalyst by a three-component coupling reaction (A3 reaction) of aldehydes, amines, and alkynes to give the corresponding propargylamines in good to excellent yields.

NbCl5 serves as an efficient catalyst for the intermolecular [2+2+2] cycloaddition of alkynes and alkenes to afford 1,3-cyclohexadienes. A convenient system has been developed using excess alkene, which enables the reaction to proceed without using low-valent niobium reagents or any reductants. This catalytic system affords 1,3-cyclohexadiene with high chemo- and regioselectivity, in contrast to a previously reported system involving NbCl3(DME) as a low-valent niobium catalyst.

We report the use of a DMF reduction method for straightforward synthesis of binary solid solution Cu–Pd nanoparticles (NPs) over the entire range of composition. The resulting NPs were uniform in size (less than 2.5 nm), tunable in composition, and exhibited photoluminescence properties that were nonlinear in composition. These binary solid solution NPs showed enhanced photoluminescence intensity and quantum yield compared to those of the single-metal NPs and their mixtures. The highest quantum yield of 3.10% for Cu–Pd alloy NPs synthesized using equimolar feeding ratio versus 2.75% for Cu and 0.71% for Pd NPs was obtained. These enhancements make the alloy NPs promising materials for optical applications.

NbCl 5 -mediated amidation of olefins with nitriles was successfully achieved. Various aliphatic, cyclic, and aromatic olefins, and various aliphatic and aromatic nitriles were used in this reaction to give secondary amides in high yields.

NbCl

A NbCl

This paper summarizes recent advances in α-alkylation reactions based on hydrogen borrowing methodologies using alcohol as an alkylating agent. This review provides a summary of recent progress toward the α-alkylation of carbonyl substrates, as well as relatively unactivated substrates bearing fewer acidic α-hydrogens, such as acetonitriles, acetamides, esters, methylpyrimidines, and methylquinolines. A summary of recent improvements in α-methylation strategies based on hydrogen borrowing methodologies has also been provided. Particular emphasis has been placed on highly practical and green chemistry approaches involving modified catalytic systems, including metal-supported heterogeneous catalysts and nanoparticle-based catalysts, as well as reactions conducted in the absence of a transition-metal catalyst. A review of recent achievements in methylation strategies using methanol as a methyl source, and their application to the α-methylation of ketones using transition-metal catalyzed hydrogen borrowing me...

A simple and practical method of cyanation of benzyl chlorides and trimethylsilyl cyanide was achieved, using the Ni(cod)2/PPh3 catalyst system, to give arylacetonitriles.

N,N-Dimethylformamide-stabilized palladium nanoclusters showed high catalytic activity for Migita–Kosugi–Stille cross-coupling reactions. The present cross-coupling reaction proceeded efficiently using very small Pd catalyst loadings under ligandless, and even an open air, conditions. The reactions proceeded smoothly in good yields and with high turnover numbers of up to 3.5 × 104.