Bis Indolyl Methanes Research Articles

Correction: Metal-free oxidative coupling of arylmethylamines with indoles: a simple, environmentally benign approach for the synthesis of 3,3′-bis(indolyl)methanes

Correction for ‘Metal-free oxidative coupling of arylmethylamines with indoles: a simple, environmentally benign approach for the synthesis of 3,3′-bis(indolyl)methanes” by Vikas D. Kadu et al., RSC Adv., 2020, 10, 23254–23262, DOI: 10.1039/D0RA03221B.

Solar light degradation of organic dye pollutants and preparation of bis(indolyl)methanes using core-shell Fe3O4@SiO2@CuO nanocomposite.

In this research, a new ferromagnetic-recoverable core-shell Fe3O4@SiO2@CuO nanocomposite of a certain size (20-25 nm) has been synthesized based on Cu(II) complex coated on Fe3O4@SiO2 nanoparticles by facile and fast solid state microwave irradiation method. The photocatalytic activity of the nanocomposite was investigated for degradation of methylene blue (MB) and methyl orange (MO) dye pollutants in aqueous media under solar light irradiation. The nanocomposite could destroy these dyes with high efficiency in short time. With comparison of degradation percentages can be concluded that the nanocomposite shows better photocatalytic activity for MB dye (97% in 180 s). Kinetic study revealed higher rate constant for degradation of MB (k= 3.6×10-3 s-1) with pseudozero-order model. Also, Fe3O4@SiO2@CuO nanocomposite was an efficient magnetically recoverable catalyst for the preparation of bis(indolyl)methanes (BIMs) through the condensation of an aldehyde with 2 equivalents of indole in EtOH/H2O as green solvents.

Seralite SRC-120 resin catalyzed synthesis of bis(indolyl)methanes using indoles and low/high boiling point carbonyl compounds under solvent free conditions

A highly inexpensive, and operationally simple seralite SRC-120 (strongly acidic cation exchange resin) catalyzed synthesis of 3,3′-bis(indolyl)methanes (BIMs) from indoles and low/high boiling point carbonyl compounds under solvent-free condition is reported. Synthesis of BIMs with low boiling point carbonyls at room temperature takes prolonged reaction time and give low yields at high temperature. The reported method overcomes these limitations and works remarkably well with low/high boiling point aldehydes/ketones in shorter reaction times (5–10 min) under microwave irradiation conditions and provides moderate to excellent yields (65–94%). Moreover, the recyclability of the catalyst for at least five times without notable loss in activity makes the whole process attractive and green protocol.

Magnetically recyclable CuFe2O4 catalyst for efficient synthesis of bis(indolyl)methanes using indoles and alcohols under mild condition

Bis(3-indolyl)methanes (BIM) are highly valuable and appear in the core structure of many natural products and pharmacologically active compounds (anticancer, anti-inflammatory, antiobesity, antimetastatic, antimicrobial, etc.). Herein, we have disclosed an air stable and highly efficient CuFe2O4 heterogeneous catalyst for alkylation of indoles with alcohols to give bis(3-indolyl)methanes in very good yields. The CuFe2O4 catalyst has been found to be magnetically recycled at least five times without losing significant catalytic activity.

Chitosan-supported copper salt and copper metal nanoparticles/copper (I) oxide microcrystals: Efficient and recyclable heterogeneous catalysts for the synthesis of bis(indolyl)methanes

Chitosan (CTS)-supported-CuSO4 (CTS-CuSO4) and CTS-supported-Cu metal nanoparticles/Cu2O microcrystals (CuNPs/Cu2OMCs) heterogeneous catalysts were developed through a simple, eco-friendly, efficient, and homogeneous immobilization methodology, by exploiting the chelation capacity of CTS. Notably, the CTS-CuSO4 and CTS-CuNPs/Cu2OMCs catalysts lead to process intensification for the synthesis of bis(indolyl)methanes (BIMs) through the promotion of catalyst recovery and reusability in up to five catalysis/recovery cycles, solvent-free reactions under mild conditions, high product yields, low amounts of catalysts, and no metal waste, owing to catalyst recovery and reuse. Different crystal structures of Cu2OMCs are obtained in combination with CuNPs through the chemical reduction of CuSO4 using ascorbic acid as a reducing agent, which is a simple procedure that can be conducted under mild reaction conditions. Moreover, we establish that the CTS-CuNPs/Cu2OMCs heterogeneous catalyst is an effective alternative to CTS-CuSO4 in BIM synthesis when aliphatic aldehydes are used. This is the first report on the use of CTS-CuSO4 and CTS-CuNPs/Cu2OMCs catalysts for the synthesis of BIMs through a low-cost, simple, eco-friendly, and sustainable approach.

Convenient Synthesis and Anticancer Activity of Bis(aryl)alkanes and Bis(indolyl)methane Alkaloid Analogs

An efficient metal free high yield method of synthesis of bis(indolyl)methanes (BIMs) and bis(aryl)alkanes analogs in the presence of B(C6F5)3 by condensation of primary amines with pyruvates has been successfully developed. Some analogs of BIMs display good in vitro antitumor activity, screened by MTT assay. Compound 3b demonstrates the best anti-cancer activity against lung carcinoma cell A549 cells with IC50 of 4.52 µM.

Synthesis and Catalytic Application of Bimetallic and Trimetallic Magnetic Nanoalloys for the Preparation of Bis(indolyl)methanes

Synthesis and Catalytic Application of Bimetallic and Trimetallic Magnetic Nanoalloys for the Preparation of Bis(indolyl)methanes

Synthesis of silica chemisorbed bis(hydrogensulphato)benzene (SiO2–BHSB) as a new hybrid material and it's utility as an efficient, recyclable catalyst for the green synthesis of bis(indolyl)methanes

Synthesis of silica chemisorbed bis(hydrogensulphato)benzene (SiO2-BHSB) was achieved as a new hybrid catalytic material, its structure, stoichiometry and stability was established using modern analytical techniques such as CP-MAS 13C NMR, CP-MAS 29Si NMR, EDX, FT-IR, TGA and DTG. The synthesised material SiO2–BHSB was observed as an environmentally benign, recyclable catalyst for the synthesis of bis(indolyl)methanes (BIMs) via an electrophilic substitution reaction of indoles by aldehydes or ketones under solvent free grinding condition. A range of structurally diverse aldehydes, ketones and indoles were smoothly undergone the developed catalytic protocol to offer good to excellent yields of corresponding bis(indolyl)methane derivatives in shorter reaction times. The synthesised material SiO2–BHSB showed a sustained catalytic activity up to five cycles of its reuse for the synthesis of BIMs. The catalytic protocol offered a chemo-selective route for the synthesis of BIMs, in which aldehydes are pushed exclusively in presence of ketones to undergo the reaction. Simple working procedure, ease of isolation of the catalyst, environmentally compatible energy conditions and no side products are the additional salient features of this protocol.

Selectivity Control in Gold-Catalyzed Hydroarylation of Alkynes with Indoles: Application to Unsymmetrical Bis(indolyl)methanes.

Gold-catalyzed hydroarylation of unactivated alkynes with indoles have previously been reported to proceed with double indole addition to produce symmetrical bis(indolyl)methanes (BIMs). We demonstrate for the first time that the selectivity of the gold-catalyzed reaction can be fully switched to allow for isolation of the vinylindole products instead. Furthermore, this selective reaction can be utilized to synthesize the more difficult to access unsymmetrical BIMs from readily available starting materials.

“Inorganic Polymer Flocculation Catalyst”—Polyaluminum chloride as highly efficient and green catalyst for the Friedel-crafts alkylation of bis(indolyl)methanes

The classic inorganic polymer flocculant—polyaluminum chloride (PAC)—was used as an environmentally friendly, efficient, and recyclable catalyst in the synthesis of Bis(indolyl)methanes (BIMs) compounds for the first time. The strategy of catalysis is to use PAC as a Lewis acid, which contains different structures of Al–O polynuclear cations. These Al atoms may have a special synergistic catalytic effect for synthesis of BIMs compounds. PAC exhibits excellent catalytic activity in both solution (Yield: 95%) and solid phase (Yield: 99%). In addition, the PAC catalyst possesses outstanding stability and can be reused at least 4 times. Therefore, PAC may have wider applications in the synthesis of other organic compounds.

Site reactivity of indole derivatives with pentachloropyridine

The reaction of pentachloropyridine with indoles and bis(indolyl)methanes (BIMs) were investigated. Indoles in basic medium exclusively react with pentachloropyridine to give the corresponding N-perhalopyridine substituted indoles. Furthermore, BIMs in reaction with pentachloropyridine gave N-perfluoropyridinated BIMs and N,N´-bis(perfluoropyridyl) bis(indolyl)methane derivatives, as major and minor products, respectively. The structures of all the compounds were confirmed by elemental analysis, IR, 1H NMR and 13C NMR spectroscopy.

Bisindolization Reaction Employing Phthalimide-N-sulfonic Acid as an Efficient Catalyst

Background: Bis(indolyl) methanes (BIMs) have a wide spectrum of applications in biomedicine and agriculture as well as are present in natural products. These bisheterocyclic compounds possess vast pharmacological, including antifungal, antitubercular, anti-inflammatory, antibacterial, anticancer, anticonvulsant, antibiotic, antiviral, antimalarial, analgesic, and antidiabetic properties. BIMs scaffolds have also been employed as selective optical chemosensors for detection of some anions and cations with the naked eye. Because of the importance of these bisheterocycles, various methods have been reported for their synthesis through reaction of indole derivatives and aldehydes or ketones. Therefore, the synthesis of BIMs through different methodologies has received widespread attention in the field of organic synthesis and medicinal chemistry. Objective: In this study, the catalytic activity of phthalimide-N-sulfonic acid (PISA) as an efficient and safe solid acidic organocatalyst toward the synthesis of BIMs derivatives in ethanol is described. Methods: Indole derivatives (2 mmol), aryl/heteroaryl aldehydes (1 mmol), and PISA (10 mol%) were mixture in ethanol. The reaction mixture was stirred at room temperature for the appropriate times. After workup and separation of catalyst, the corresponding heterocyclic products were obtained through recrystallization from hot ethanol. Results: The BIMs derivatives were easily obtained via Bisindolization Reaction (BIR) of two indoles (2-methylindole and indole) with a series of aryl and heteroaryl aldehydes. The BIR was efficiently catalyzed at room temperature using PISA as an excellent organocatalyst under optimized reaction conditions. Conclusion: The reactions were implemented in simple manner and were completed within acceptable reaction times. The expected BIM products were obtained in satisfactory yields. The catalyst can be recovered and reused several times in the template reaction. This approach provides the benefits of convenience, simple operational procedure, no use of hazardous organic solvents, cheapness and ease of preparation of catalyst.

Synthesis, Characterization, and Properties of Highly Hydrophilic Polyaniline Sulfonic Acid

A hollow spherical highly hydrophilic polyaniline sulfonic acid catalyst has been successfully prepared by emulsion polymerization and SO3 liquid sulfonation using modified polystyrene microspheres (PS) as a template. Acid value of the solid acid catalyst is 2.516 mmol/g. Morphology, structure and thermal stability of the catalyst have been studied by XRD, SEM, TEM, FT-IR, X-ray photoelectron spectroscopy (XPS), and TGA. It has been proven that doping and sulfonation of PANI and SO3 lead to new molecule that retains the PANI matrix material. In view of close structure-activity relationship, it has been applied to the efficient synthesis of bis(indolyl)methanes (BIMs) in water-ethanol phase.

Perfluoropyridylation of indoles via reaction of perfluorinated pyridines with indole compounds

The reaction of perfluoropyridines with indoles and bis(indolyl)methanes (BIMs) was investigated. The aromatic nucleophilic substitution of pentafluoropyridine with indoles occurs at the 4-position of pyridine ring by nitrogen site of indolyl anion, while reaction with 2,3,5,6-tetrafluoro-4-(phenylsulfonyl)pyridine gave a mixture of products arising substitution at 2-position of pyridine ring and replacement of phenylsulfonyl group. Furthermore, the reaction of pentafluoropyridine with BIMs yielded mixture of mono- and bis-perfluoropyridyl products.

First, in situ generated Mannitol-Boron or Sorbitol-Boron chelate complex as a novel, recyclable catalyst for the highly efficient synthesis of bis(indolyl)methanes, tris(indolyl)methanes and diindolyl (carbazolyl)methanes.

Abstract The first report on in situ generated Mannitol-Boron or Sorbitol-boron chelate complex, as a novel, recyclable homogenous, eco-benign catalyst for the liquid phase electrophilic substitution reactions of indoles with aromatic aldehydes or indole aldehydes or carbazole aldehydes to afford the corresponding bis(indolyl)methanes or tris(indolyl)methanes or di(indolyl) carbazolyl methanes in ethanol or aqueous ethanol at ambient temperature in good to excellent yields. This methodology is mild, highly efficient using minor quantities of catalyst with no side products and a very simple work-up procedure. The effect of solvent, the effect of substituents and the influence of mole ratio are also investigated. The addition of mannitol or sorbital to boric acid in excess formed mainly a 2, 2-di-borate ester which can be effectively removed from reaction waste water (> 97%) by subjecting the reaction waste water to reverse osmosis.

The impact of metal coordination on the assembly of bis(indolyl)methane-naphthalene-diimide amphiphiles.

The self-assembly and coordination of amphiphiles comprised of naphthalenediimide (NDI) and bis(indolyl)methane (BIM) chromophores were investigated as a function of pH and metal. As observed by TEM, SEM and AFM imaging, the self-assembly of NDI-BIM 1 produced irregular nanostructures at neutral pH in CH3CN-H2O (1 : 1); whereas, well-defined nanotubes were observed at pH 2. Conversely, Fmoc-protected, NDI-BIM 2 formed nanotubes at neutral pH and nonspecific aggregates at pH 2. Upon coordination of Cu2+ ions to the bis(indoyl)methane moiety, a reorganization from nanotubes to vesicular structures was observed.

C‐C Bond Cleavage by the Reaction of Cyclic Amines or Indoles with Activated Olefins: A Redox‐Neutral Mechanism for the Reducing Action of Tetrahydroisoquinolines

AbstractHere we report the C−C bond cleavage through the reaction of tetrahydroisoquinolines (THIQs) or indoles with activated olefins. THIQ reacts with olefins under catalyst‐ and solvent‐free condition resulting the formation of N‐benzyltetrahydroisoquinoline via the C−C bond cleavage followed by reduction of iminium ion. Here, THIQ behaves as a reducing agent. On the other hand, when indole is used in place of THIQ in presence of ceric ammonium nitrate as catalyst under solvent‐free condition, symmetrical bisindolylmethanes (BIMs) are obtained. The methodology could be further extended to synthesize unsymmetrical BIMs.

Copper‐Phosphine Supported Fe3O4@SiO2 as a Novel Reusable Nanocatalyst‐Catalyzed Tandem Reaction of Indole and Alcohols to Bis(indolyl)methanes under Blue LED Light

AbstractNano Fe3O4@SiO2@TPP−Cu as a novel heterogeneous nanocatalyst was prepared and authenticated by usual analytical and spectroscopic techniques. The prepared Fe3O4@SiO2@TPP−Cu was applied to preparation of bis(indolyl)methane derivatives via a three‐component reaction of aromatic alcohols with indoles under blue led lights. The advantages of this method are the selective oxidation of alcohols under mild conditions. In addition, the recycling studies revealed that catalyst could be easily recovered using an external magnet and reused for five times without significant loss of its catalytic activity.

Natural deep eutectic solvents in the hetero-Diels–Alder approach to bis(indolyl)methanes

For the first time, the use of natural deep eutectic solvents (NADES) as reaction media to carry out hetero-Diels–Alder reactions is disclosed. This allowed to improve the efficiency and sustainability of the synthetic approach to bis(indolyl)methanes (BIMs) based on bis-hetero-Diels–Alder/conjugate addition reactions of nitroso- and azoalkenes with indoles. The ternary mixture of H2O with choline chloride/glycerol allowed the tuning of the physical properties of this NADES leading to a better solvent system, affording the target hydroxyiminomethyl- and hydrazonomethyl-BIMs, in much shorter reaction times, higher efficiency and easier isolation procedures. Furthermore, the direct access to carbonyl-BIMs was possible when 3-methyl-1-tert-butoxycarbonyl azoalkenes were used.

Supported Iridium Catalyst for the Green Synthesis of 3,3′-Bis(indolyl)methanes Using Methanol As the Bridging Methylene Source

The first example of a heterogeneous catalyst based on hydrotalcite-derived Mg–Al oxides supported iridium (Ir/MgxAlO) for activation of methanol in the synthesis of bis(indolyl)methanes (BIMs) is ...