PEG-400 as an efficient reaction medium for the synthesis of 2,4,5-triaryl-1H-imidazoles and 1,2,4,5-tetraaryl-1H-imidazoles

Preparation of polysubstituted imidazoles using AC-SO3H/[Urea]7[ZnCl2]2 as an efficient catalyst system: a novel method, and α-glucosidase inhibitor activity

Deep eutectic solvents (DESs) act as both an organic solvent and a useful catalyst for organic synthesis reactions, especially the synthesis of heterocyclic compounds containing the element nitrogen. DESs exhibit many important properties namely large liquid fields, biodegradability, outstanding thermal stability, and moderate vapor pressure. Amorphous carbon-bearing sulfonic acid groups (AC-SO₃H) are one of the new-generation solid acids showing strong acid activity. Based on the simultaneous presence of acidic functional groups such as carboxylic acid, phenolic, and sulfonic acid groups, they exhibit many important activities namely strong Brønsted acid, high surface area, high stability, reusability, and recyclability. In this study, AC-SO₃H was made from rice husk via the carbonization and sulfonation processes, and the surface properties and structure were examined using contemporary methods such as FT-IR, P-XRD, TGA, SEM, and EDS. And, [Urea]₇[ZnCl₂]₂ was synthesized from urea and ZnCl₂ with a mole ratio of 7 : 2; the structure is defined using FT-IR and TGA. By combining AC-SO₃H and [Urea]₇[ZnCl₂]₂ we aim to form an effective catalyst/solvent system for the preparation of polysubstituted imidazole derivatives through the multi-component cyclization reaction from nitrobenzenes, benzil, aldehydes, and ammonium acetate. The major products are obtained with high isolation yields above 60%. To assess the catalyst system's activity, the recovery and reusability of the AC-SO₃H/[Urea]₇[ZnCl₂]₂ system were examined with hardly any performance modification. In an effort to create potential enzyme α-glucosidase inhibitors, several novel polysubstituted imidazoles were created. Five of these compounds showed good enzyme α-glucosidase inhibitor activity. The most effective substances were IMI-13, IMI-15, and IMI-20, with IC₅₀ values that were greater than the acarbose at 16.5, 15.8, and 11.6 μM, respectively - the acarbose (IC₅₀, 214.5 μM) as the positive control.

An efficient green protocol for the synthesis of 1,2,4,5-tetrasubstituted imidazoles in the presence of ZSM-11 zeolite as a reusable catalyst

In this study, we have synthesized a series of ZSM-11 zeolite catalysts using tetrapropyl ammonium hydroxide as a structure-directing agent through a highly efficient hydrothermal method. The series of catalysts were studied by different techniques such as FT-IR spectroscopy, XRD, FE-SEM, HR-TEM, EDS, pyridine-FT-IR spectroscopy, and BET analysis. We focused on varying reaction time intervals from 18 to 48 hours to investigate the effect on catalytic activities of the synthesized series of catalysts. The percentages of aluminum increased in the framework of zeolites with increasing crystallinity, surface area, external surface area, and acidity in the series of ZSM-11 zeolites by increasing the time from 18 to 48 h. Then, we studied the catalytic activity of a series of ZSM-11 zeolites and found that the ZSM-11 zeolite (48 h) possesses higher catalytic activity towards the synthesis of 1,2,4,5-tetrasubstituted imidazoles under solvent-free conditions. The present protocol scored well with excellent yield, short reaction time, clean reaction profiles, low catalyst loading, and no tedious workup. The catalyst (ZSM-11 zeolite 48 h) was recycled and reused in five runs without any considerable loss of activity and product yield.

One Pot Synthesis and Pharmacological Evaluation of Aryl Substituted Imidazoles as Potential Atypical Antipsychotics

Background:

Second generation or “atypical” antipsychotics demonstrate an improved therapeutic profile over conventional neuroleptics. These are effective in both positive and negative symptoms of the disease and have a lower propensity to induce adverse symptoms.

Objective:

The main objective of the research was in silico design and synthesis of potential atypical antipsychotics with combined antiserotonergic / antidopaminergic effect.

Methods:

A one pot synthesis of aryl substituted imidazole derivatives was carried out in green solvent PEG-400 and the prepared compounds were evaluated for atypical antipsychotic activity in animal models for dopaminergic and serotonergic antagonism. The compounds were designed based on their 3D similarity studies to standard drugs and in silico (docking studies) with respect to 5-HT2A and D2 receptors.

Results:

Results from the docking studies with respect to 5-HT2A and D2 receptors suggested a potential atypical antipsychotic profile for the test compounds. Theoretical ADME profiling of the compounds based on selected physicochemical parameters suggested an excellent compliance with Lipinski’s rules. The potential of these compounds to penetrate the blood brain barrier (log BB) was computed through an online software program and the values obtained for the compounds suggested a good potential for brain permeation. Reversal of apomorphine induced mesh climbing behaviour coupled with inactivity in the stereotypy assay indicates antidopaminergic effect and a potential atypical profile for the test compounds 1-5. Further, the activity of compounds in DOI assay indicated a 5-HT2 antagonistic profile (5-HT2 antagonism).

Conclusion:

Compound 5 emerged as important lead compound showing combined antidopaminergic and antiserotonergic (5-HT2A) activity with a potential atypical antipsychotic profile.

Visible light-emitting diode light-driven one-pot four component synthesis of poly-functionalized imidazoles under catalyst- and solvent-free conditions

A visible light-emitting diode light-driven green and sustainable protocol has been demonstrated for the one-pot four component synthesis of poly-functionalized imidazoles under catalyst- and solvent-free conditions.

An efficient and recyclable nanocatalyst for the green and rapid synthesis of biologically active polysubstituted pyrroles and 1,2,4,5-tetrasubstituted imidazole derivatives

An effective process for the green and rapid synthesis of biologically active polysubstituted pyrroles and 1,2,4,5-tetrasubstituted imidazoles derivatives using Cu@imine/Fe₃O₄ MNPs catalyst under solvent-free conditions is explained. This catalyst showed high reactivity for the synthesis of a set of different derivatives of polysubstituted pyrroles and 1,2,4,5-tetrasubstituted imidazole derivatives under appropriate reaction conditions and short times. Moreover, the catalyst was also recycled and reused for six runs with no considerable reduction in reactivity and yields. Compared to the reported procedures, this method consistently demonstrates the advantages of low catalyst loading, short reaction times, easy separation and purification of the products, high yields, and high recoverability and recoverability of the catalyst.

So the use of Fe₃O₄@SiO₂–ZrCl₂-MNPs leads to an improved protocol in terms of the compatibility with the environment, yields of the products, reaction times and the amount of the catalyst when compared with other catalysts.

Ionophore silica-coated magnetite nanoparticles as a recyclable heterogeneous catalyst for one-pot green synthesis of 2,4,5-trisubstituted imidazoles

Novel multi-SO3H functionalized strong Brønsted acidic ionic liquid coated magnetite nanoparticles have been prepared and applied as catalyst for the synthesis of 2,4,5-trisubstituted imidazoles. The results showed that a novel catalyst was very efficient for the reaction and could be magnetically separated and reused at least 6 times with less reduction in its catalytic activity. Operational simplicity, low cost of the catalyst used, high yields, environmental friendliness, wide applicability, reusability and easy recovery of the catalyst using an external magnet are the most important features of this methodology. The catalyst was characterized by Fourier transform infrared spectroscopy (FT-IR), X-Ray diffraction analysis (XRD), field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray analysis (EDX), dynamic laser scattering (DLS) and vibrating sample magnetometry (VSM).

A waste to wealth approach through utilization of nano-ceramic tile waste as an accessible and inexpensive solid support to produce a heterogeneous solid acid nanocatalyst: to kill three birds with one stone

Waste minimization through the utilization of cost-effective, available, and nontoxic nano-ceramic tile wastes for the heterogenization of sulfuric acid.

Isocyanurate-based periodic mesoporous organosilica (PMO-ICS): a highly efficient and recoverable nanocatalyst for the one-pot synthesis of substituted imidazoles and benzimidazoles

Isocyanurate bridging periodic mesoporous organosilica (PMO-ICS) was shown to be a highly active and efficient recyclable nanocatalyst for three-component synthesis of trisubstituted imidazole as well as benzimidazole derivatives in EtOH.

γ-Alumina Nanoparticle Catalyzed Efficient Synthesis of Highly Substituted Imidazoles

γ-Alumina nano particle catalyzed multi component reaction of benzil, arylaldehyde and aryl amines afforded the highly substituted 1,2,4,5-tetraaryl imidazoles with good to excellent yield in less reaction time under the sonication as well as the conventional methods. Convenient operational simplicity, mild conditions and the reusability of catalyst were the other advantages of this developed protocol.

Graphene oxide–chitosan bionanocomposite: a highly efficient nanocatalyst for the one-pot three-component synthesis of trisubstituted imidazoles under solvent-free conditions

An eco-friendly and clean GO–biopolymer heterogeneous nanocatalyst was prepared and characterized, which efficiently promoted an important organic reaction.

Fe3O4@SiO2·HM·SO3H as a recyclable heterogeneous nanocatalyst for the microwave-promoted synthesis of 2,4,5-trisubstituted imidazoles under solvent free conditions

A simple, highly versatile and efficient synthesis of 2,4,5-trisubstituted imidazoles catalyzed by Fe₃O₄@SiO₂·HM·SO₃H is achieved via a three component one pot reaction of benzil, benzaldehyde and NH₄OAc.

One-pot synthesis of multisubstituted imidazoles under solvent-free conditions and microwave irradiation using Fe3O4@SiO2–imid–PMAn magnetic porous nanospheres as a recyclable catalyst

Synthesis of substituted imidazoles using the Fe₃O₄@SiO₂–imid–PMAⁿ nanocatalyst.

Iron nanotube-silica composite (ZVI-S-PCAT modified silica composite) preparation, characterization and application as a recyclable catalytic system for 5-membered ring organic transformations

The ZVI-S-PCAT modified silica composite is a successful catalytic framework for synthesizing 5-membered heterocylic rings and a future sensor material.