On Water: Br?nsted Acidic Ionic Liquid [(CH2)4SO3HMIM][HSO4] Catalysed Synthesis of Oxindoles Derivatives

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.

Silica-Coated Magnetic-Nanoparticle-Supported DABCO-Derived Acidic Ionic Liquid for the Efficient Synthesis of Bioactive 3,3-Di(indolyl)indolin-2-ones

In this work, biologically significant 3,3-di(indolyl)indolin-2-ones have been synthesized using a silica-coated magnetic-nanoparticle-supported 1,4-diazabicyclo[2.2.2]octane (DABCO)-derived and acid-functionalized ionic liquid as the catalytic entity. The fabricated nanocomposite catalyzes the pseudo-three-component reaction of isatins and indoles explicitly via hydrogen-bonding interactions between substrates and the catalyst. The nanocatalytic system utilizes water as the green reaction medium to obtain a library of indolinones in good to excellent yields under mild reaction conditions. Besides, the catalyst could be easily recovered from the reaction mixture through simple external magnetic forces, which enables excellent recyclability of the catalyst for successive runs without appreciable loss in catalytic activity. Hence, the outcomes of the present methodology make the nanocatalyst a potential candidate for the development of green and sustainable chemical processes.

Nano-SiO2: a heterogeneous and reusable catalyst for the one-pot synthesis of symmetrical and unsymmetrical 3,3-di(aryl)indolin-2-ones under solvent-free conditions

Symmetrical and unsymmetrical 3,3-di(aryl)indolin-2-ones have been synthesized by nano-SiO2 as green, heterogeneous, and reusable catalyst under solvent-free conditions at room temperature via magnetic stirring and grinding methods. A plausible mechanism of condensation has also been presented.

An efficient synthesis of 3-indolyl-3-hydroxy oxindoles and 3,3-di(indolyl)indolin-2-ones catalyzed by sulfonated β-CD as a supramolecular catalyst in water

Sulfonated-β-cyclodextrin (β-CD-SO3H) promoted efficient and fast electrophilic substitution reaction of indoles with various isatins reflux in water is reported affording various 3-indolyl-3-hydroxy oxindoles and 3,3-di(indolyl)indolin-2-ones in good to excellent yields in short reaction time.