Inexpensive Ruthenium Research Articles

Ru(II)-Catalyzed Carboamination of Olefins with α-Carbonyl Sulfoxonium Ylides.

The first ruthenium-catalyzed carboamination of olefins with α-carbonyl sulfoxonium ylides is reported. The utilization of an inexpensive ruthenium catalyst enables the concise synthesis of pharmaceutically important isoindolin-1-ones, which possess both a stereogenic center and β-carbonyl side chain. This method is mild, efficient, and scalable and allows for the coupling of a wide range of aryl-, heteroaryl-, alkenyl-, and alkyl-substituted sulfoxonium ylides. Moreover, the carbonyl side chain in the resulting product provides a good handle for downstream transformations. For mechanistic studies, a ruthacyle complex is obtained and proven to be the key intermediate in both catalytic and stoichiometric reactions.

Synthesis of Substituted Pyrido[1,2‐a]benzimidazoles by Ruthenium‐Catalyzed C−H Bond Activation and Tandem Cyclization of 2‐Arylimidazo[1,2‐a]pyridines with Iodonium Ylides

AbstractRuthenium‐catalyzed C−H bond activation and tandem cyclization of 2‐arylimidazo[1,2‐a]pyridines with iodonium ylides proceed efficiently. For the first time, the easily available iodonium ylides and inexpensive ruthenium complex were employed to synthesize pyrido[1,2‐a]benzimidazole derivatives in good yields under simple and easy‐to‐operate conditions. Several primary mechanism investigations and synthetic applications involving gram‐scale preparation, derivatization reactions and the transformation of iodonium ylide generated in situ have also been conducted.

Fabrication of Ruthenium-Based Transition Metal Nanoparticles/Reduced Graphene Oxide Hybrid Electrocatalysts for Alkaline Water Splitting

Green hydrogen has attracted significant attention as one of the future energy sources because no greenhouse gases are emitted during production and its energy density is much higher than fossil fuels. Precious metals such as platinum (Pt) and iridium (Ir)-based catalysts are commonly used for water splitting catalysts. However, because of high cost of these precious metals, the mass production of green hydrogen is restricted. In this study, water splitting catalysts based on relatively inexpensive ruthenium (Ru), cobalt (Co), and iron (Fe) were synthesized. The metal nanoparticles were anchored on reduced graphene oxide (rGO) by a microwave-assisted process. The nanoparticles were uniformly distributed on the rGO supports with sizes of about 1.5 and 2 nm in Ru/rGO and RuCoFe/rGO, respectively. This promoted the reaction by further increasing the specific surface area of the catalysts. In addition, it was confirmed by EDS mapping results that the nanoparticles were made of RuCoFe alloy. Among the prepared catalysts, Ru/rGO was excellent toward the hydrogen evolution reaction (HER), which required an overpotential of 50 mV to reach a current density of −10 mA cm<sup>−2</sup>. In addition, RuCoFe/rGO, which contained the RuCoFe alloy, was the best for the oxygen evolution reaction (OER), and it required 362 mV at the current density of 10 mA cm<sup>−2</sup>.

Ruthenium(II)-Catalyzed Ortho-C-H Alkylation of Naphthylamines with Diazo Compounds for Synthesis of 2,2-Disubstituted π-Extended 3-Oxindoles in Water.

Ruthenium(II)-catalyzed ortho-C-H alkylation of naphthylamines with diazo compounds for the synthesis of 2,2-disubstituted π-extended 3-oxindoles has been developed. The method represents the first example of C-H alkylation via carbenoid insertion in water as a sustainable solvent. The procedure includes an inexpensive ruthenium catalyst as well as aqueous media and results in the release of benign N2. The π-extended 3-oxindole products exhibit favorable antitumor properties and remarkable fluorescent properties in aqueous solution for fluorescent imaging.

Inexpensive Ruthenium NNS‐Complexes as Efficient Ester Hydrogenation Catalysts with High C=O vs. C=C Selectivities

AbstractRu(NNS)(PPh3)Cl2 (NNS=2‐(methylthio)‐N‐(pyridin‐2‐yl‐methyl)ethan‐1‐amine) was employed in the hydrogenation of α,β‐unsaturated esters, reaching selectivities for the allylic alcohol up to 95% in the hydrogenation of iso‐butylcinnamate. In addition, several ester substrates were hydrogenated with catalyst loadings as low as 0.05 mol%. Surprisingly, selectivity of the hydrogenation of the C=O vs the C=C bonds strongly depends on the solvent.magnified image

Ruthenium-catalyzed olefinic C-H alkenylation of enol-carbamates: highly stereo-selective synthesis of (Z,Z) and (Z,E)-butadienes.

Cross-coupling reactions of enol carbamates with alkynes or alkenes are reported, using an inexpensive ruthenium catalyst. With the assistance of the directing group OCONMe2, the protocols provide mild, stereo-selective and efficient routes for the preparation of valuable (Z,Z) and (Z,E)-butadiene skeletons.

A direct cross-coupling reaction of electron-deficient alkenes using an oxidizing directing group.

An oxidant-free cross-coupling reaction of electron-deficient alkenes using an inexpensive ruthenium catalyst is reported. With the assistance of the oxidizing directing group CONH(OMe), this protocol provides a mild, straightforward and efficient method for the preparation of valuable 1,3-butadiene skeletons with excellent Z,E selectivities.

Ortho-C-H Arylation of Benzoic Acids with Aryl Bromides and Chlorides Catalyzed by Ruthenium.

A system consisting of catalytic amounts of [(p-cym)RuCl2 ]2 /PEt3 ⋅HBF4 , K2 CO3 as the base, and NMP as the solvent efficiently mediates the ortho-C-H arylation of benzoic acids with aryl bromides at 100 °C. Replacing the phosphine ligand with the amino acid dl-pipecolinic acid enables the analogous transformation with aryl chlorides. The key advantage of this broadly applicable transformation is the use of an inexpensive ruthenium catalyst in combination with simple carboxylates as directing groups, which can either be tracelessly removed or used as anchor points for decarboxylative ipso substitutions.

Ortho‐C−H Arylation of Benzoic Acids with Aryl Bromides and Chlorides Catalyzed by Ruthenium

AbstractA system consisting of catalytic amounts of [(p‐cym)RuCl2]2/PEt3⋅HBF4, K2CO3 as the base, and NMP as the solvent efficiently mediates the ortho‐C−H arylation of benzoic acids with aryl bromides at 100 °C. Replacing the phosphine ligand with the amino acid dl‐pipecolinic acid enables the analogous transformation with aryl chlorides. The key advantage of this broadly applicable transformation is the use of an inexpensive ruthenium catalyst in combination with simple carboxylates as directing groups, which can either be tracelessly removed or used as anchor points for decarboxylative ipso substitutions.

Ruthenium(II)-Catalyzed Alkene C-H Bond Functionalization on Cinnamic Acids: A Facile Synthesis of Versatile α-Pyrones.

An inexpensive ruthenium(II) complex enabled oxidative annulation of alkynes by using cinnamic acid derivatives to provide diversely decorated multisubstituted α-pyrones.

Ruthenium-catalysed alkoxycarbonylation of alkenes with carbon dioxide

Alkene carbonylations represent a major technology for the production of value-added bulk and fine chemicals. Nowadays, all industrial carbonylation processes make use of highly toxic and flammable carbon monoxide. Here we show the application of abundantly available carbon dioxide as C1 building block for the alkoxycarbonylations of industrially important olefins in the presence of a convenient and inexpensive ruthenium catalyst system. In our system, carbon dioxide works much better than the traditional combination of carbon monoxide and alcohols. The unprecedented in situ formation of carbon monoxide from carbon dioxide and alcohols permits an efficient synthesis of carboxylic acid esters, which can be used as detergents and polymer-building blocks. Notably, this transformation allows the catalytic formation of C-C bonds with carbon dioxide as C1 source and avoids the use of sensitive and/or expensive reducing agents (for example, Grignard reagents, diethylzinc or triethylaluminum).

ChemInform Abstract: Ruthenium‐Catalyzed Direct Oxidative Alkenylation of Arenes Through Twofold C—H Bond Functionalization

AbstractReview: 161 refs.

Ruthenium-catalyzed direct oxidative alkenylation of arenes through twofold C–H bond functionalization

Significant progress has been accomplished in direct olefinations through twofold C–H bond functionalization of arenes and heteroarenes employing readily accessible, selective and relatively inexpensive ruthenium catalysts. Particularly, ruthenium(II) complexes have allowed challenging direct double C–H/C–H bond alkenylations of arenes with ample scope. These catalysts set the stage for step-economical C–H/C–H bond functionalization with electron-rich as well as electron-deficient arenes and heteroarenes, and, thereby, provide versatile access to diversely decorated styrenes.

Hydroxyl-Directed Ruthenium-Catalyzed C–H Bond Functionalization: Versatile Access to Fluorescent Pyrans

Hydroxyl-assisted oxidative annulations of alkynes were accomplished with an inexpensive ruthenium(II) complex, delivering fluorescent pyrans via highly site selective as well as chemo- and regioselective C-H/O-H bond functionalizations.

Ruthenium-Catalyzed Oxidative Synthesis of 2-Pyridones through C–H/N–H Bond Functionalizations

An inexpensive ruthenium catalyst enabled oxidative annulations of alkynes by acrylamides with ample scope, which allowed for the preparation of 2-pyridones employing various electron-rich and electron-deficient acrylamides as well as (di)aryl- and (di)alkyl-substituted alkynes.

Ruthenium Chloride as an Efficient Catalytic Precursor for Hydroarylation Reactions via C−H bond Activation

A very simple and efficient catalytic system for the hydroarylation of olefins by aromatic ketones and Michael acceptors using simple and inexpensive ruthenium trichloride as a ruthenium source is described. These very mild conditions (dioxane at 80 degrees C) appeared to be highly compatible, tolerant, and selective toward various functional groups, and the ease of the protocol is highly convenient for synthetic purposes.

Ru-Catalyzed Regiospecific Borylation of Methyl C-H Bonds

Alkylboronic derivatives are recently gaining interest as synthetic intermediates, due to the raising amount of newly discovered transformations involving these versatile organometallics. Direct catalytic C-H activation is a new synthetic approach which is of great interest and offers new ways of functionalization of organic substrates. This is the first report of the use of relatively inexpensive ruthenium catalysis for the borylation of simple alkanes. The reaction is highly selective for Me groups and requires 2-5 mol% of Ru species as catalyst. β-Amino- and -alkoxyboronic derivatives, unavailable by conventional organometallic methods, can be obtained from the corresponding N- and O-alkyl species using this elegant approach.

Carbon-supported palladium-ruthenium catalyst for hydropurification of terephthalic acid

The ruthenium-incorporated catalyst, (0.3% Pd–0.2% Ru)/CCM (carbon carbonaceous composite material) catalyst, has been studied as a candidate to replace an existing 0.5% Pd/C catalyst for hydropurification of crude terephthalic acid; it gives an excellent performance and is a promising catalyst. It has been confirmed that the (0.3% Pd–0.2% Ru)/CCM catalyst has higher stability in actual commercial condition and aging in lab condition compared with a commercial catalyst. The increased stability may be explained as the effect of ruthenium to prevent the sintering of supported metal particles. The (0.3% Pd–0.2% Ru)/CCM catalyst shows equal or less amount of side reaction of benzene ring hydrogenation. The dust from carbon support can also be decreased from the (0.3% Pd–0.2% Ru)/CCM catalyst due to the increased strength of the CCM. The (0.3% Pd–0.2% Ru)/CCM catalyst may be very competitive to the existing catalyst due to the inexpensive ruthenium and the expected long life of the catalyst.