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Catalytic Asymmetric Synthesis of Cycloalkanes via Cascade Reactions of Nitroalkenes
Published in Irishi N. N. Namboothiri, Meeta Bhati, Madhu Ganesh, Basavaprabhu Hosamani, Thekke V. Baiju, Shimi Manchery, Kalisankar Bera, Catalytic Asymmetric Reactions of Conjugated Nitroalkenes, 2020
Irishi N. N. Namboothiri, Meeta Bhati, Madhu Ganesh, Basavaprabhu Hosamani, Thekke V. Baiju, Shimi Manchery, Kalisankar Bera
The Enders group developed an asymmetric nitro-Michael/Henry domino reaction of γ-nitro aldehydes 38 or ketones 37 with nitroalkenes 1 employing squaramide-based organocatalyst C7 to form polysubstituted 1,2,3,4-tetrahydronaphthalen-1-ols 40 or secondary/tertiary cyclohexanols 39 possessing four contiguous stereocenters (Scheme 10.13).47 Nucleophilic addition of the γ-nitro aldehyde 38 to the nitroalkene 1 followed by an intramolecular Henry reaction yields the products 39/40.
Synthesis of nitroaldols through the Henry reaction using a copper(II)–Schiff base complex anchored on magnetite nanoparticles as a heterogeneous nanocatalyst
Published in Journal of Coordination Chemistry, 2021
Niloufar Parandeh-Khoozani, Mohsen Moradian
The Henry reaction is a significant reaction in organic chemistry that was discovered in 1895 by Henry [1]. The coupling between nitroalkanes and carbonyl compounds in the presence of base gives C-C bond formation to produce nitroaldols [2–5]. Nitroaldols are useful primary substrates to synthesize other compounds [6–11]. Also, these materials are used as an efficient intermediate in preparation of drugs such as antibiotics, anthracycline, norephedrine and ephedrine [12, 13]. Furthermore, nitroolefins are obtained [14, 15] via dehydration of nitroaldol intermediates [16]. In these processes, different catalysts were used such as BINOL [17], alkaloid [18], metal complexes [19–21], alkali metal hydroxide [22], alkoxides [23], ammonium acetate [24], carbonates [25] and amines [26, 27]. The copper and their ions in different oxidation states play a crucial role as a catalyst in the synthesis of nitroaldols through the Henry reaction. Various reports of copper ions as a core of a catalyst for both homogeneous or heterogeneous systems work very well in this reaction [28–53].
A heterogeneous mesoporous catalyst based on anchored copper: Schiff base complex into SBA-15 for the synthesis of benzimidazoles from orthoesters
Published in Inorganic and Nano-Metal Chemistry, 2022
Ghasem Rezanejade Bardajee, Shohreh Hekmat, Aseyeh Ghaedi, Farideh Goudarzi
The performance of mesoporous materials can be improved by covalent anchoring of various functional groups on its surface. For instance, the SO3H-functional groups attached to the ordered inner pore walls of mesoporous structures based on SiO2 was prepared and its properties was investigated by gas adsorption combined with in situ small angle neutron scattering.[6] 4,4′-Diaminodiphenyl sulfone functionalized SBA-15 (DDS/SBA-15) with various loading amounts of DDS has been prepared via a post synthesis grafting method and it was served as a promising candidate for both volatile organic compound vapor sensing and proton conducting materials.[3] The Proline was immobilized on to Al-SBA-15 and SBA-15 as bifunctional acid–base materials, and they were applied for C–C bond-forming reactions. The entitled bifunctional acid–base materials were established at different reactions including Knoevenagel reaction, tandem deacetalization–Knoevenagel reaction, one-pot deacetalization–Henry reaction, aldol reaction, and nitroaldol reaction.[7] Another bifunctional mesoporous silica nanoparticles (MSN) containing both amine and sulfonic acid groups (MSN–NNH2–SO3H) showed excellent catalytic activity in carbon–carbon coupling reactions like the nitroaldol reaction, whereas the homogeneous catalysts were unable to initiate the reaction due to their mutual neutralization in solution.[8] The incorporation of transition metal ions as Lewis acid sites onto the surface of functionalized SBA-15 can also treat the catalytic activity of these compounds. SBA-15 is an interesting mesoporous silica material having highly ordered nanopores and a large surface area, which is widely employed as absorbents, drug delivery materials and as solid materials for support of molecular catalysts in order to transform them into heterogeneous catalysts.