Microwave-assisted, montmorillonite K-10 catalyzed three-component synthesis of 2H-indazolo[2,1-b]phthalazine-triones under solvent-free conditions

Nitrogen-bridgehead compounds: overview, synthesis, and outlook on applications

The nitrogen-bridgehead is a common structural motif present in a multitude of natural products. As many of these abundant compounds exhibit biological activities, e.g. against cancer or bacteria, these derivatives are of high interest. While natural products are often associated with problematic characteristics, such as elaborate separation processes, high molecular complexity and limited room for derivatization, purely synthetic approaches can overcome these challenges. Many synthetic procedures have been reported for preparation of artificial nitrogen bridgehead compounds, however, to our surprise only a fraction of these has been tested for their bioactivity. This review is therefore meant to give an overview of existing synthetic methods that provide scaffolds containing bridgehead nitrogen atoms, covering the period from 2000 to 2023. Reviews which cover subunits of this topic are referenced as well.

Montmorillonite-catalysed coupling reactions: a green overview

Coupling reactions are widely significant in organic synthesis, and within the green chemistry perspective the utilization of montmorillonite clay as a catalyst offers a viable alternative to traditional coupling protocols. Montmorillonite clay is an effective, eco-friendly, economic and recyclable catalyst, and its heterogeneous nature facilitates easy isolation and reusability. The majority of coupling reactions executed with montmorillonite catalysts offer notable advantages over their homogeneous counterparts, including enhanced efficiency, selectivity, operational simplicity, elimination of toxic solvents and ligands, maintenance of mild reaction conditions, and cost-effectiveness. This review gives a comprehensive summary of the literature to date on coupling reactions catalysed by montmorillonite clay, while also outlining future prospects in this area.

Montmorillonite clay-based heterogenous catalyst for the synthesis of nitrogen heterocycle organic moieties: a review

The use of montmorillonite clay as solid catalyst has grabbed much attention in the liquid phase reactions for organic synthesis. In recent years, there has been a lot of interest in organic synthesis using montmorillonite-based composites, especially in the synthesis of heterogeneous nanoparticles. Due to the robust and green nature of montmorillonite-based nanocatalysts, it has been widely used in N-heterocyclic reactions. In this review, we have concentrated on the reports pertaining the use of montmorillonite-based nanocatalyst in the synthesis of N-heterocycles, a category of organic compounds with excellent biological properties. This manuscript is arranged by the types of N-containing heterocycles synthesized using montmorillonite-based composite as catalysts including polycyclic spirooxindoles, heterocyclic propargylamine, indole-based heterocycles, quinoline and its derivatives, six-membered N-heterocyclic-based compounds and five-membered N-heterocyclic-based compounds. Special attention was given to the structural stability under experimental parameters of the montmorillonite-based composite with the incidence of metal leaching and reusability. Finally, along with recent developments, new findings in heterogeneous montmorillonite (Mt)-based catalysis have also been addressed.

Sulfonated β-cyclodextrins: efficient supramolecular organocatalysts for diverse organic transformations

The present review summarizes various organic transformations carried out by using sulfonated β-cyclodextrins such as β-cyclodextrin sulfonic acid, β-cyclodextrin propyl sulfonic acid, and β-cyclodextrin butyl sulfonic acid as an efficient, supramolecular reusable catalyst under diverse reaction conditions.

Benzodiazines: recent synthetic advances

This review provides a comprehensive overview of the recent developments in synthetic strategies for benzodiazines, important scaffolds in medicinal chemistry.

Multicomponent Facile Synthesis of Highly Substituted [1,2,4]Triazolo[1,5-a] Pyrimidines

A simple and convenient method for one-pot synthesis of a series of potentially biologically active [1,2,4]triazolo[1,5- a]pyrimidine-6-carboxamide derivatives has been developed in solvent-free conditions using maltose as a commercially available, cheap and eco-friendly catalyst. The salient features of the present protocol are mild reaction conditions, good to excellent yields, high atom economy, benign environmental conditions, easy isolation of products without column chromatography and clean reaction profiles.

Synthesis and characterization of Ni(ii)–Vanillin–Schiff base–MCM-41 composite as an efficient and reusable nanocatalyst for multicomponent reactions

Ni(ii)–Vanillin–Schiff base–MCM-41 has been synthesized and characterized by XRD, TGA, BET, EDS, SEM, ICP-OES, TEM and FT-IR spectroscopy. This nanostructural catalyst has been applied for multicomponent reactions.

A mesoporous SBA-15 silica catalyst functionalized with phenylsulfonic acid groups (SBA-15-Ph-SO3H) as a novel hydrophobic nanoreactor solid acid catalyst for a one-pot three-component synthesis of 2H-indazolo[2,1-b]phthalazine-triones and triazolo[1,2-a]indazole-triones

Phenyl sulfonic acid functionalized mesoporous SBA-15 silica was prepared through the silanization of activated mesoporous SBA-15 with diphenyldichlorosilane followed by silylation and sulfonation.

Molybdate sulfuric acid (MSA): an efficient reusable catalyst for the synthesis of tetrahydrobenzo[4,5]imidazo[2,1-b]quinazolin-1(2H)-ones under solvent-free conditions and evaluation of their in vitro bioassay

The attractive features of this methodology are green and easy workability with high product yields. All the title compounds have good to excellent anti-oxidant and anticancer activity.

A highly efficient and recyclable cobalt ferrite chitosan sulfonic acid magnetic nanoparticle for one-pot, four-component synthesis of 2H-indazolo[2,1-b]phthalazine-triones

A novel magnetical cobalt ferrite chitosan sulfonic acid (CoFe₂O₄-CS-SO₃H) was prepared and identified as an efficient catalyst for synthesis of 2H-indazolo[2,1-b]phthalazine-triones by one-pot, four-component reaction.