Ruthenium catalysts bearing chelating carboxylate ligands: application to metathesis reactions in water

Protocol for olefin metathesis reactions of hydrophobic substrates performed in aqueous emulsion with mechanical stirring or with microwaves support

In the presented protocol, we describe the olefin metathesis of hydrophobic substrates in water emulsions using ruthenium catalysts in the presence of air. We detail the testing of mechanical foaming for emulsification and the use of microwave heating to optimize metathesis reaction efficiency. By utilizing relatively low catalyst loading and ensuring simple product isolation, the steps outlined in this protocol extend known methods for the aqueous metathesis techniques. For complete details on the use and execution of this protocol, please refer to Tyszka-Gumkowska et al. (2022).

Fast Initiating Furan-Containing Hoveyda-Type Complexes: Synthesis and Applications in Metathesis Reactions

Two new ruthenium complexes with chelating-ether benzylidene ligands bearing a furan moiety were synthesized and characterized, including X-ray crystallography. They initiated fast, also at 0 °C, and were found to be highly active in a variety of ring-closing, ene-yne, and cross-metathesis reactions, including an active pharmaceutical ingredient (API) model, which makes them good candidates for the transformation of complex polyfunctional compounds that require mild reaction conditions.

Testing enabling techniques for olefin metathesis reactions of lipophilic substrates in water as a diluent

Olefin metathesis reactions of diverse polyfunctional substrates were conducted in water emulsions using two hydrophobic ruthenium catalysts in the presence of air. Instead of using surfactants to increase the efficiency of the metathesis reaction in water, ultrasound and microwave techniques were tested on a small-scale reaction, whereas conventional heating and mechanical stirring were effective enough to provide high conversion and selectivity on a larger scale. The developed conditions extend known protocols for the aqueous metathesis methodology, utilizing relatively low catalyst loadings and allowing for simple product isolation and purification. The established synthetic protocol was successfully adopted in the large-scale synthesis of a pharmaceutically related product – sildenafil (Viagra) derivative.

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Sustainable approach for metathesis reaction in water emulsion system on air.

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Utilization of enabling techniques for boosting metathesis under aqueous conditions.

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RCM of medically important sildenafil derivative.

Fluorine-containing ruthenium-based olefin metathesis catalysts

The review summarizes literature data on the methods for the introduction of fluorine atoms and fluoralkyl groups into different ligands to construct metathesis-active ruthenium carbene complexes. It also analyzes the influence of fluorinated ligands on the catalytic activity of the complexes. The choice, structure and positions of fluorinated substituents in NHC ligands are generally dictated by the desire to increase the electrophilicity of the ruthenium atom due to the electron-withdrawing effect of fluorine atoms and fluoroalkyl groups, resulting, as a rule, in an increase in the activity of the ruthenium complex. In catalysts with unsymmetrical fluorine-containing NHC ligands, there is a possibility of additional Ru–F coordination, making the complexes much more stable and, consequently, more active. The presence of fluorine in chelating alkylidene ligands provides an increase in the catalyst initiation rate due to a weakening of the ruthenium – heteroatom bond. Besides, the introduction of polyfluoroalkyl groups into ligands solves the problem of catalyst recovery using fluorous biphasic systems for reuse.

The bibliography includes 172 references.

Olefin metathesis catalysts embedded in β-barrel proteins: creating artificial metalloproteins for olefin metathesis

This review summarizes the recent progress of Grubbs-Hoveyda (GH) type olefin metathesis catalysts incorporated into the robust fold of β-barrel proteins. Anchoring strategies are discussed and challenges and opportunities in this emerging field are shown from simple small-molecule transformations over ring-opening metathesis polymerizations to in vivo olefin metathesis.

Forged and fashioned for faithfulness-ruthenium olefin metathesis catalysts bearing ammonium tags

In this article, the synthesis and applications of selected ammonium tagged Ru-alkylidene metathesis catalysts were described. Because of the straightforward synthesis, the first generation of onium-tagged catalysts have the ammonium group installed in the benzylidene ligand. Such catalysts usually give relatively pure metathesis products, and are used in polar solvents and water, or immobilised on various supports. Later, catalysts tagged in the N-heterocyclic carbene ligand (NHC) were developed to offer higher stability and even lower metal contamination levels. Due to minimal leaching, the non-dissociating ligand tagged systems were successfully immobilised on various supports, including zeolites and Metal Organic Frameworks (MOFs) and used in batch and in continuous flow conditions.

Olefin metathesis in air using latent ruthenium catalysts: imidazole substituted amphiphilic hydrogenated ROMP polymers providing nano-sized reaction spaces in water

Imidazole substituted hydrogenated amphiphilic ROMP polymers were used as both surfactants and ligand precursors for olefin metathesis reactions in water.

Metatheases: artificial metalloproteins for olefin metathesis

Recent advance in the design of artificial metalloproteins for olefin metathesis is presented.

Microwave-ultrasound simultaneous irradiation: a hybrid technology applied to ring closing metathesis

Glycerol micelles were suitable nanoreactors for ring-closing metathesis reaction activated by a hybrid microwave-ultrasound reactor. Nine different Ru-catalysts were investigated.