Diastereoselective hydrogenation of arenes and pyridines using supported ruthenium nanoparticles under mild conditions

A convenient and practical diastereoselective cis-hydrogenation of multi-substituted pyridines and arenes is reported. Applying a novel heterogeneous ruthenium catalyst, the corresponding piperidines and cyclohexanes are obtained in high yields (typically >80%) with a good functional group tolerance under mild conditions. The robust ruthenium supported catalyst is smoothly prepared and can be reused multiple times without activity loss.

Single-Step Sustainable Production of Hydroxy-Functionalized 2-Imidazolines from Carbohydrates

Manufacturing valuable N-containing chemicals from biomass is highly desirable yet challenging. Herein, a novel strategy was developed for efficient production of 2-(1-hydroxyethyl)-imidazoline (HI), a high-value and versatile building block for synthesizing a myriad of bioactive targets, directly from carbohydrates under mild reaction conditions. With this strategy, bio-based HI was produced from fructose in one step with as high as 77 C % isolated yield in the presence of ethylenediamine (EDA) and InCl₃ at 130 °C. The synergistic functions of EDA and InCl₃ were identified for the transformation, wherein EDA promoted the scission of C-C bond of fructose backbone via retro-aldol (R-A) reaction and rapidly trapped in-situ formed reactive carbonyl-containing C₃ intermediate for HI formation to avoid undesired side reaction, and InCl₃ facilitated the formation of this C₃ intermediate and the final 1,2-hydrid shift step.

2,2'-Dipyridylamines: more than just sister members of the bipyridine family. Applications and achievements in homogeneous catalysis and photoluminescent materials

2,2'-Dipyridylamines (dpa) and related compounds belong to the family of polydentate nitrogen ligands. More than a century has passed since their first report but new complexes and applications have been emerging in recent years owing to the versatility of dpa-based architectures. This review aims to present and highlight the main achievements attained with dpa-containing metal complexes in the domains of homogeneous catalysis and luminescent materials.

Iridium-Catalyzed Hydrogenation and Dehydrogenation of N-Heterocycles in Water under Mild Conditions

An efficient catalytic method is presented for the hydrogenation of N-heterocycles. The iridium-based catalyst operates under mild conditions in water without any co-catalyst or stoichiometric additives. The catalyst also promotes the reverse reaction of dehydrogenation of N-heterocycles, hence displaying appropriate characteristics for a future hydrogen economy based on liquid organic hydrogen carriers (LOHCs).

Iridium-Catalyzed Hydrogenation and Dehydrogenation of N-Heterocycles in Water under Mild Conditions

An efficient catalytic method is presented for the hydrogenation of N-heterocycles. The iridium-based catalyst operates under mild conditions in water without any co-catalyst or stoichiometric additives. The catalyst also promotes the reverse reaction of dehydrogenation of N-heterocycles, hence displaying appropriate characteristics for a future hydrogen economy based on liquid organic hydrogen carriers (LOHCs).

Formic acid as a hydrogen source for the iridium-catalyzed reductive amination of levulinic acid and 2-formylbenzoic acid

A robust iridium catalyst performs the reductive amination of the renewable levulinic acid and of 2-formylbenzoic acid in water under mild conditions. This catalyst tolerates very bulky reagents.

Transformations of terpenes and terpenoids via carbon–carbon double bond metathesis

The review reports on transformations of unsaturated terpenes and terpenoids via olefin metathesis processes including ring closing metathesis of dienes, cross metathesis with functional olefins and ethenolysis, and ring opening metathesis as well as ring opening/cross metathesis.

Selective and Efficient Iridium Catalyst for the Reductive Amination of Levulinic Acid into Pyrrolidones

The catalytic reductive amination of levulinic acid (LA) into pyrrolidones with an iridium catalyst using H₂ as hydrogen source is reported. The chemoselective iridium catalyst displayed high efficiency for the synthesis of a variety of N-substituted 5-methyl-2-pyrrolidones and N-arylisoindolinones. N-Substituted 5-methyl-2-pyrrolidone was also evaluated as a biosourced substitute solvent to NMP (N-methylpyrrolidone) in the catalytic arylation of 2-phenylpyridine.

Ethenolysis: A Green Catalytic Tool to Cleave Carbon-Carbon Double Bonds

Remarkable innovations have been made in the field of olefin metathesis due to the design and preparation of new catalysts. Ethenolysis, which is cross-metathesis with ethylene, represents one catalytic transformation that has been used with the purpose of cleaving internal carbon-carbon double bonds. The objectives were either the ring opening of cyclic olefins to produce dienes or the shortening of unsaturated hydrocarbon chains to degrade polymers or generate valuable shorter terminal olefins in a controlled manner. This Review summarizes several aspects of this reaction: the catalysts, their degradation in the presence of ethylene, some parameters driving their productivity, the side reactions, and the applications of ethenolysis in organic synthesis and in potential industrial applications.

Cross metathesis of unsaturated epoxides for the synthesis of polyfunctional building blocks

The cross metathesis of 1,2-epoxy-5-hexene (1) with methyl acrylate and acrylonitrile was investigated as an entry to the synthesis of polyfunctional compounds. The resulting cross metathesis products were hydrogenated in a tandem fashion employing the residual ruthenium from the metathesis step as the hydrogenation catalyst. Interestingly, the epoxide ring remained unreactive toward this hydrogenation method. The saturated compound resulting from the cross metathesis of 1 with methyl acrylate was transformed by means of nucleophilic ring-opening of the epoxide to furnish a diol, an alkoxy alcohol and an amino alcohol in high yields.

Ruthenium(ii) and iridium(iii) complexes featuring NHC–sulfonate chelate

Three new complexes bearing a chelating (κ²C,O) NHC-SO₃ ligand have been prepared.

Terminal conjugated dienes via a ruthenium-catalyzed cross-metathesis/elimination sequence: application to renewable resources

Two-step synthesis of terminal 1,3-dienes catalyzed by two different ruthenium complexes.

Methyl ricinoleate as platform chemical for simultaneous production of fine chemicals and polymer precursors

The modification of methyl ricinoleate by etherification of the hydroxyl group was accomplished by using a nonclassical ruthenium-catalyzed allylation reaction and also by esterification. Methyl ricinoleate derivatives were engaged in ring-closing metathesis (RCM) reactions leading to biosourced 3,6-dihydropyran and α,β-unsaturated lactone derivatives with concomitant production of polymer precursors. Sequential RCM/hydrogenation and RCM/cross-metathesis were also implemented as a straightforward method for the synthesis of tetrahydropyran and lactone derivatives as well as valuable monomers (i.e., polyamide precursors).

Ene-yne cross-metathesis with ruthenium carbene catalysts

Conjugated 1,3-dienes are important building blocks in organic and polymer chemistry. Enyne metathesis is a powerful catalytic reaction to access such structural domains. Recent advances and developments in ene–yne cross-metathesis (EYCM) leading to various compounds of interest and their intermediates, that can directly be transformed in tandem procedures, are reviewed in this article. In addition, the use of bio-resourced olefinic substrates is presented.

Improving sustainability in ene-yne cross-metathesis for transformation of unsaturated fatty esters

Ruthenium-catalyzed ene-yne cross-metathesis is performed with stoichiometric proportions of terminal olefins and alkynes. This is made possible by the continuous addition of the alkyne to the reaction mixture. The protocol allows the ene-yne cross-metathesis reaction to be carried out with long-chain terminal olefins and in a one-pot fashion with internal olefins after shortening by ethenolysis. The efficient conversion of renewable unsaturated fatty esters from bioresources into valuable conjugated 1,3-dienes of interest for further transformations is performed using this technique under mild conditions in dimethyl carbonate; an ecofriendly solvent.