Magnetic Nanoparticle-Supported Morita–Baylis–Hillman Catalysts

Magnetic nanoparticle-supported eosin Y salt [SB-DABCO@eosin] as an efficient heterogeneous photocatalyst for the multi-component synthesis of chromeno[4,3-b]chromene in the presence of visible light

Heterogeneous photocatalysts present a favourable procedure to realize green and eco-friendly organic reactions. We have demonstrated an SB-DABCO@eosin catalyst in a green one-pot multi-component protocol for the production of various chromeno[4,3-b]chromenes via condensation of aromatic aldehydes and dimedone under the photo-redox catalyst bearing eosin Y using visible light. The synthesized nanocatalyst was characterized using various physicochemical techniques such as FT-IR, XRD, EDX, UV-vis, SEM, TGA and DRS. The significant advantages of the present methodology include excellent yield, cost-effectiveness, easy work-up, 100% atom economy, broad substrate scope, easy separation and efficient recycling. Furthermore, the evidence showed that the investigated condensation reaction proceeds via a radical mechanism, which proved the need for reactive species such as OH˙ and ˙O2 - in the photocatalytic process. In addition to the improved handling and process control, the yield of products and the rate of reactions have increased considerably in the present strategy. Reproducibility studies also guarantee good reusability and stability of the nanocatalyst for at least five runs.

A highly efficient magnetic solid acid nanocatalyst for the synthesis of new bulky heterocyclic compounds

Fe₃O₄nanoparticles were coated with 3-aminopropyltriethoxysilane and further chemically modified with maleic anhydride to generate Fe₃O₄@APTES·MAH NPs. Then some new bulky heterocyclic compounds were synthesized using this catalyst.

A nano-organo catalyzed route towards the efficient synthesis of benzo[b]pyran derivatives under ultrasonic irradiation

Organocatalyst crafted on silica supported ferrite nanoparticle (Fe₂O₃@SiO₂@VB₁) for 4H-benzo[b]pyrans synthesis.

Palladium stabilized by 3,4-dihydroxypyridine-functionalized magnetic Fe3O4nanoparticles as a reusable and efficient heterogeneous catalyst for Suzuki reactions

A Pd supported on 3,4-dihydroxypyridine (Py)-functionalized Fe₃O₄(Fe₃O₄/Py/Pd) hybrid material has been synthesized for the first time.

Copper immobilized ferromagnetic nanoparticle triazine dendrimer (FMNP@TD–Cu(ii))-catalyzed regioselective synthesis of 1,4-disubstituted 1,2,3-triazoles

The synthesis, characterisation and catalytic activity of FMNP@TD–Cu(ii) for the synthesis of 1,4-disubstituted 1,2,3-triazoles are reported.

Multivalency as a key factor for high activity of selective supported organocatalysts for the Baylis-Hillman reaction

The polystyrene-supported N-alkylimidazole-based dendritic catalysts for the Baylis-Hillman reaction exhibit one of the strongest beneficial effects of multivalent architecture ever reported for an organocatalyst. The yields in the model reaction of methyl vinyl ketone with p-nitrobenzaldehyde are more than tripled when a non-dendritic catalyst is replaced by a second- or third-generation analogue. Moreover, the reaction of the less active substrates will not occur with the non-dendritic catalyst and will proceed to a significant extent only with the analogous catalysts of higher generations. A substantial additional enhancement of the reaction yield could be achieved by increasing the content of water in the reaction solvent. The plausible cause of the dendritic effect is the assistance of the second, nearby imidazole moiety in the presumably rate-determining proton transfer in the intermediate adduct, after the first imidazole unit induced the formation of the new carbon-carbon bond.

Excellent catalytic activity of magnetically recoverable Fe3O4–graphene oxide nanocomposites prepared by a simple method

An easy-to-prepare Fe₃O₄–graphene oxide nanocomposite which works well as a reusable catalyst for A³-coupling reactions.

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.

Palladium nanoparticles supported on agarose-functionalized magnetic nanoparticles of Fe3O4 as a recyclable catalyst for C–C bond formation via Suzuki–Miyaura, Heck–Mizoroki and Sonogashira–Hagihara coupling reactions

Palladium nanoparticles supported on agarose functionalized Fe₃O₄ catalyzed C–C bond formation reactions.

Preparation and characterization of novel magnetic nanocomposite-bonded metalloporphyrins as biomimetic nanocatalysts

In this work, novel magnetic nanocomposite-bonded metalloporphyrins were synthesized by an effective silanation approach between 3-aminopropyltriethoxysilane derivatized metalloporphyrins and silica-coated magnetic Fe3O4 nanoparticles. The initial metalloporphyrin derivatives were synthesized by the amidation reaction of metalloporphyrin acyl chloride with 3-aminopropyltriethoxysilane. After the metalloporphyrin derivatives were adsorbed on the surface of silica-coated magnetic Fe3O4 nanoparticles, the solid mixture was heated under vacuum at 110 °C for 3 h and then thoroughly washed with chloroform. The obtained magnetic nanocomposite-bonded metalloporphyrins were characterized by elemental analyzer, low-temperature N2 adsorption (BET method), transmission electron microscopy, UV-vis spectroscopy, and infrared spectroscopy. Interestingly, using this particular silanation method, metalloporphyrins could be quantitative-immobilized in magnetic nanocomposites by controlling the input ratio of metalloporphyrins and silica-coated magnetic Fe3O4 nanoparticles. The excellent catalytic activity and recyclability of the magnetic nanocomposite-bonded metalloporphyrins were demonstrated in the cyclohexane oxidation with iodosylbenzene.