Superparamagnetic Nanoparticle-Supported (S)-Diphenyl- prolinol Trimethylsilyl Ether as a Recyclable Catalyst for Asymmetric Michael Addition in Water

Factors influencing the performance of organocatalysts immobilised on solid supports: A review

Organocatalysis has become a powerful tool in synthetic chemistry, providing a cost-effective alternative to traditional catalytic methods. The immobilisation of organocatalysts offers the potential to increase catalyst reusability and efficiency in organic reactions. This article reviews the key parameters that influence the effectiveness of immobilised organocatalysts, including the type of support, immobilisation techniques and the resulting interactions. In addition, the influence of these factors on catalytic activity, selectivity and recyclability is discussed, providing an insight into optimising the performance of immobilised organocatalysts for practical applications in organic chemistry.

Enantioselective Construction of Spirooxindole-Fused Cyclopentanes

The present study reports an asymmetric organocatalytic cascade reaction of oxindole derivates with α,β-unsaturated aldehydes efficiently catalyzed by simple chiral secondary amine. Spirooxindole-fused cyclopentanes were produced in excellent isolated yields (up to 98%) with excellent enantiopurities (up to 99% ee) and moderate to high diastereoselectivities. The synthetic utility of the protocol was exemplified on a set of additional transformations of the corresponding spiro compounds. In addition, a study showing the promising biological activity of selected enantioenriched products was accomplished.

Asymmetric organocatalysis: an enabling technology for medicinal chemistry

The efficacy and synthetic versatility of asymmetric organocatalysis have contributed enormously to the field of organic synthesis since the early 2000s. As asymmetric organocatalytic methods mature, they have extended beyond the academia and undergone scale-up for the production of chiral drugs, natural products, and enantiomerically enriched bioactive molecules. This review provides a comprehensive overview of the applications of asymmetric organocatalysis in medicinal chemistry. A general picture of asymmetric organocatalytic strategies in medicinal chemistry is firstly presented, and the specific applications of these strategies in pharmaceutical synthesis are systematically described, with a focus on the preparation of antiviral, anticancer, neuroprotective, cardiovascular, antibacterial, and antiparasitic agents, as well as several miscellaneous bioactive agents. The review concludes with a discussion of the challenges, limitations and future prospects for organocatalytic asymmetric synthesis of medicinally valuable compounds.

Iron Oxide-Cobalt Nanocatalyst for O-tert-Boc Protection and O-Arylation of Phenols

Efficient and general protocols for the O-tert-boc protection and O-arylation of phenols were developed in this paper using a recyclable magnetic Fe₃O₄-Co₃O₄ nanocatalyst (Nano-Fe-Co), which is easily accessible via simple wet impregnation techniques in aqueous mediums from inexpensive precursors. The results showed the catalysts were well characterized by XRD (X-ray Diffraction), ICP-AES (Inductive Coupled Plasma Atomic Emission Spectroscopy), TEM (Transmission Electron Microscopy), TOF-SIMS (Time-Of-Flight Secondary Ion Mass Spectrometry) and XPS (X-ray Photoelectron Spectroscopy). The O-tert-boc protection and O-arylation of phenols was accomplished in good to excellent yields (85–95%) and the catalyst was reusable and recyclable with no loss of catalytic activity for at least six repetitions.

Silica gel-immobilized multidisciplinary materials applicable in stereoselective organocatalysis and HPLC separation

In this pilot study, we present novel bifunctional silica gel-immobilized materials applicable as heterogeneous organocatalysts and stationary phases in HPLC. The materials provided high stereoselectivity in both batch and continuous flow catalysis of a model Michael addition (cyclohexanone to (E)-β-nitrostyrene). In the batch reaction, the catalysts proved their sustainable catalytic activity over five consecutive recycling experiments. Under continuous flow reaction conditions, the catalytic activity was found to be superior to the batch reaction, and moreover, the same immobilized materials were utilized as stationary phases in HPLC showing very good chemoselective separation of model acidic analytes.

Novel multidisciplinary silica gel-based materials were successfully employed in highly stereoselective Michael addition and as stationary phases in HPLC separation.

Catalytic Organic Reactions in Water toward Sustainable Society

Traditional organic synthesis relies heavily on organic solvents for a multitude of tasks, including dissolving the components and facilitating chemical reactions, because many reagents and reactive species are incompatible or immiscible with water. Given that they are used in vast quantities as compared to reactants, solvents have been the focus of environmental concerns. Along with reducing the environmental impact of organic synthesis, the use of water as a reaction medium also benefits chemical processes by simplifying operations, allowing mild reaction conditions, and sometimes delivering unforeseen reactivities and selectivities. After the "watershed" in organic synthesis revealed the importance of water, the development of water-compatible catalysts has flourished, triggering a quantum leap in water-centered organic synthesis. Given that organic compounds are typically practically insoluble in water, simple extractive workup can readily separate a water-soluble homogeneous catalyst as an aqueous solution from a product that is soluble in organic solvents. In contrast, the use of heterogeneous catalysts facilitates catalyst recycling by allowing simple centrifugation and filtration methods to be used. This Review addresses advances over the past decade in catalytic reactions using water as a reaction medium.

Highly enantioselective Michael addition of cyclohexanone to nitroolefins catalyzed by pyrrolidine-based bifunctional benzoylthiourea in water

Organocatalysis and aqueous reactions are identified as the focus of the greening of chemistry. Combining these two strategies effectively remains an interesting challenge in organic synthesis. Herein, we used pyrrolidine-based benzoylthiourea 1c to catalyze the asymmetric Michael addition of cyclohexanone to various nitroolefins in water to afford the corresponding compounds in moderate to good yields, and with excellent diastereoselectivities (up to >99:1 dr) and enantioselectivities (up to 99% ee).

A recyclable Mn–porphyrin catalyst for enantioselective epoxidation of unfunctionalized olefins using molecular dioxygen

A highly efficient green process for the asymmetric epoxidation of olefins by an easy to synthesise Mn–porphyrin and O₂/aldehyde is reported.

A solution to achieve good reusability of MNPs Fe3O4-supported (S)-diphenylprolinoltrimethylsilyl ether catalysts in asymmetric Michael reactions

A PVP-modified MNPs Fe₃O₄-supported Jøgensen–Hayashi catalyst to achieved good reusability with high yields and unchangeable excellent stereoselectivities in the asymmetric Michael addition of propanal to nitroalkenes.

Cu–EDTA-modified APTMS-Fe3O4@SiO2 core–shell nanocatalyst: a novel magnetic recoverable catalyst for the Biginelli reaction

A novel copper–ethylenediamine tetracarboxylate modified core–shell magnetic catalyst is introduced.

Jørgensen–Hayashi catalysts supported on poly(ethylene glycol)s as highly efficient and reusable organocatalysts for the enamine-catalyzed asymmetric Michael reaction

A new kind of recyclable and reusable PEG-supported Jørgensen–Hayashi catalyst is synthesized for the first time and proven to be efficient for the enamine-catalyzed asymmetric Michael reaction.

Resin-immobilized pyrrolidine-based chiral organocatalysts for asymmetric Michael additions of ketones and aldehydes to nitroolefins

Based on the electrostatic adsorption between acidic resins and organocatalysts, a series of resin-supported chiral organocatalysts were designed and synthesized.

Nano γ-Fe2O3-supported fluoroboric acid: a novel magnetically recyclable catalyst for the synthesis of 12-substituted-benzo[h][1,3]dioxolo[4,5-b]-acridine-10,11-diones as potent antitumor agents

Nano γ-Fe₂O₃-supported fluoroboric acid was synthesized as a novel magnetic catalyst, and was used for the efficient synthesis of benzoacridinediones.

TiO2-coated magnetite nanoparticle-supported sulfonic acid as a new, efficient, magnetically separable and reusable heterogeneous solid acid catalyst for multicomponent reactions

TiO₂-coated magnetite nanoparticles-supported sulfonic acid (nano-Fe₃O₄–TiO₂–SO₃H (n-FTSA)) is synthesized by the immobilization of –SO₃H groups on the surface of nano-Fe₃O₄–TiO₂.