Green and efficient synthesis of aryl/alkylbis(indolyl)methanes using Expanded Perlite-PPA as a heterogeneous solid acid catalyst in aqueous media

Efficient Green Synthesis, Anticancer Activity, and Molecular Docking Studies of Indolemethanes Using a Bioglycerol-Based Carbon Sulfonic Acid Catalyst

Indolemethane derivatives are significant molecules in the study of N-heterocyclic chemistry. Herein, we designed and developed a highly efficient green synthesis of indolemethane compounds using a recyclable biodegradable glycerol-based carbon solid acid catalyst under solvent-free conditions at room temperature for 5 min with excellent yields. The synthesized compounds were subjected to cytotoxic activity against prostate (DU145), hepatocellular carcinoma (HepG2), and melanoma (B16) cell lines. The highest cytotoxicity effects were found with 1k (1.09 μM) and 1c (2.02 μM) against DU145, followed by 1a, 1d, 1f, 1n, and 1m between 5.10 and 8.18 μM concentrations. The anticancer activity is validated using molecular docking simulations, and comparing binding energies with the standard drug doxorubicin suggests that the title compounds are well fitted into the active site pocket of the target molecules..

Recent Advances on Direct Functionalization of Indoles in Aqueous Media

Indoles and their derivatives have dominated a significant proportion of nitrogen-containing heterocyclic compounds and play an essential role in synthetic and medicinal chemistry, pesticides, and advanced materials. Compared with conventional synthetic strategies, direct functionalization of indoles provides straightforward access to construct diverse indole scaffolds. As we enter an era emphasizing green and sustainable chemistry, utilizing environment-friendly solvents represented by water demonstrates great potential in synthesizing valuable indole derivatives. This review aims to depict the critical aspects of aqueous-mediated indoles functionalization over the past decade and discusses the future challenges and prospects in this fast-growing field. For the convenience of readers, this review is classified into three parts according to the bonding modes (C-C, C-N, and C-S bonds), which focus on the diversity of indole derivatives, the prominent role of water in the chemical process, and the types of catalyst systems and mechanisms. We hope this review can promote the sustainable development of the direct functionalization of indoles and their derivatives and the discovery of novel and practical organic methods in aqueous phase.

Fenton oxidation catalysed by heterogeneous iron-perlite for 8-hydroxyquinoline-5-sulfonic acid (8-HQS) degradation: efficiency comparison using raw and calcined perlite as precursors for iron fixation

Herein, the catalytic activity of two types of iron-loaded perlite catalysts prepared by impregnation of raw and calcined perlite in terms of 8-hydroxyquinoline-5-sulfonic acid (8-HQS) degradation was investigated by the Fenton reaction. Different iron contents were used to optimize the Fenton catalytic reaction. The as-prepared catalysts were characterized using different spectrophotometry techniques. The effect of some operating parameters on the Fenton oxidation of 8-HQS was carried out. Iron content of 10% has led to the highest catalytic efficiency. Furthermore, the oxidation of 8-HQS is highly affected by the addition of H₂O₂, proposing that the heterogeneous Fenton reaction has been successfully activated. Whatever the type of the used catalyst, the heterogeneous catalytic oxidation process is extremely rapid, even instantaneous. The synthesized catalysts remained potentially active and retained their catalytic activity for successive Fenton reactions suggesting their economic benefit over the homogenous Fenton process. Accordingly, the newly prepared heterogeneous solid could be successfully used to treat wastewater effluents containing persistent organic compounds.

Docking Investigation on Bis (Nitro Indazolyl) Methanes; Synthesis and Antimicrobial Activity Towards Breast Cancer Applications

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Bismuth (III) nitrate pentahydrate (BN) was found to be a mild and efficient catalyst for the electrophilic condensation of 5-nitroindazole with a wide range of aldehydes to obtain Bis (5-nitro indazolyl) methanes 3 (a-h) at ambient temperature. This was structurally confirmed from FTIR, NMR, and HR-MS technique. Molecular docking studies of all compounds was carried out using breast cancer-causing human estrogen receptor (ER) from Molegro Virtual Docker software. Hydroxy Bis (nitro indazolyl) methanes (3b) were shown better binding affinities and the score obtained was -150.146 Kcal/mol compared with Tamoxifen drug. The major H-bond interactions were observed with the compound 3f and the value was -5.679. The antimicrobial activity results revealed that compounds 3b and 3d showed promising activity against bacteria Escherichia coli, Klebsiella pneumonia, Staphylococcus aureus, and Pseudomonas aeruginosa and maximum inhibition against Aspergillus niger and Aspergillus flavus. Methoxy derivatives of Bis (nitro indazolyl methanes) (3e) have shown better antioxidant activity and low MIC (6.25 µg/ml) observed for the compounds 3a and 3b. The synthesized compounds have a very promising starting point for the development and improvement of anti-breast cancer drugs.

Vapor Phase Alkylation of Isomeric Cresols with Tert-Butyl Alcohol over Perlite Supported Sulfated Zirconia Catalyst

In the present study, perlite was thermally activated and then modified desirably to generate super acidity by loading different weight percentages of sulfated zirconia (SZ) via the two-step sol-gel method. As-prepared sulfated zirconia perlite (SZP) catalysts showed suitable catalytic potential in the vapor phase alkylation of o, m, and p-cresols with tert-butyl alcohol. The presence of crystalline phases in SZP catalysts was confirmed by XRD and FT-IR studies. TEM images revealed the nano size of the catalysts in the range of 9–25 nm. The presence of SZ on the surface of perlite was further confirmed by N2 adsorption–desorption, SEM, SEM-EDX, TGA, and UV-Vis DRS techniques. The pyridine FT-IR results confirmed the existence of Brønsted, Lewis acidic sites and their combination as super acidic catalytic active centers on the surface of catalyst utilized in the vapor phase alkylation of o, m, and p-cresols with tert-butyl alcohol. The regeneration and reusability of the preferred catalyst until the 5th reaction cycle without any considerable loss in catalytic activity demonstrated the stability of the catalyst. Comparative studies show that SZP can be regenerated and is superior compared to other catalysts previously used for other alkylation reactions with the potential for use on a large scale.

Recent developments in green approaches for sustainable synthesis of indole-derived scaffolds

An important issue to discover biological structures is the design of sustainable, safe, clean, cost-effective, excellent efficient synthetic reactions, and minimal energy consumption to provide structural diversity compounds with interesting biological properties. Among five-membered nitrogen-containing heterocyclic compounds, indole-containing scaffolds are heterocyclic structures found in abundance in natural products and various synthetic compounds, which have received remarkable attention in recent years due to their therapeutic and pharmaceutical properties and valuable role in the process of drug discovery. Indoles can be synthesized by various procedures although most of these procedures have their own restrictions and drawbacks such as performing the reaction in a toxic solvent, need of transition-metal catalysts, and amount of waste solvents. Due to the medicinal importance of indole and the need for green methods of drug synthesis, this review highlights the latest green synthetic methods leading to the formation of indole-containing compounds focusing on the past 4 years with typical examples. This review is divided into two sections: green solvents and green techniques that lead to the synthesis of indole-derived scaffolds.

Chemistry of trisindolines: natural occurrence, synthesis and bioactivity

Heterocyclic nitrogen compounds are privileged structures with many applications in the pharmaceutical and nutraceutical industries since they possess wide bioactivities. Trisindolines are heterocyclic nitrogen compounds consisting of an isatin core bearing two indole moieties. Trisindolines have been synthesized by reacting isatins with indoles using various routes and the yield greatly depends on the catalyst used, reaction conditions, and the substituents on both the isatin and indole moieties. Amongst the synthetic routes, acid-catalyzed condensation reaction between isatins and indoles are the most useful due to high yield, wide scope and short reaction times. Trisindolines are biologically active compounds and show anticancer, antimicrobial, antitubercular, antifungal, anticonvulsant, spermicidal, and antioxidant activities, among others. Trisindolines have not previously been reviewed. Therefore, this review aims to provide a comprehensive account of trisindolines including their natural occurrence, routes of synthesis, and biological activities. It aims to inspire the discovery of lead trisindoline drug candidates for further development.

This in-depth review of trisindolines covers their natural occurrence in addition to several routes of synthesis and catalysts used. The biological activities of trisindolines have been discussed with a special emphasis on the structure–activity relationship.

Chickpea leaf exudates: a green Brønsted acid type biosurfactant for bis(indole)methane and bis(pyrazolyl)methane synthesis

A clean and highly efficient protocol for green synthesis of bis(indole)methanes and bis(pyrazolyl)methanes has been successfully achieved by using a naturally sourced bio-surfactant, chickpea leaf exudates (CLE), as a Brønsted acid-type catalyst.

ZnII doped and immobilized on functionalized magnetic hydrotalcite (Fe3O4/HT-SMTU-ZnII): a novel, green and magnetically recyclable bifunctional nanocatalyst for the one-pot multi-component synthesis of acridinediones under solvent-free conditions

Herein, the catalytic activity of a novel synthesized Fe₃O₄/HT-SMTU-Zn^II nanocatalyst, in the green and efficient synthesis of acridinediones, is described.

Cu(ii)-grafted SBA-15 functionalized S-methylisothiourea aminated epibromohydrin (SBA-15/E-SMTU-CuII): a novel and efficient heterogeneous mesoporous catalyst

The catalytic activity of novel synthesized SBA-15/E-SMTU-Cu^II nanocatalyst was investigated for the green, one-pot, pseudo five-component synthesis of tetrahydropyridine derivatives.