Xanthan sulfuric acid: An efficient and biodegradable solid acid catalyst for the synthesis of bis(indolyl)methanes under solvent-free conditions

Xanthan sulfuric acid (XSA) is found to be an efficient catalyst for the electrophilic substitution reaction of indole with aromatic aldehydes to afford the corresponding bis(indolyl)methanes at room temperature under solvent-free conditions. The catalyst was characterized for the first time with the help of powder XRD, SEM–EDX and DSC–TGA. The attractive features of this green, new methodology are excellent yield of products, clean reaction profile, reusability of the catalyst, energy sustainable protocol, simple experimental and easier work-up procedures.     

One-pot three-component synthesis of bis(indolyl)methanes under solvent-free condition using heteropoly-11-tungsto-1-vanadophosphoric acid supported on natural clay as catalyst

One-pot three-component condensation reaction of two moles of indole and one mole of aromatic aldehyde for the synthesis of bis(indolyl)methanes in the presence of new catalytic material, heteropoly-11-tungsto-1-vanadophosphoric acid, H₄[PV^VW₁₁O₄₀] (HPV) supported on activated natural clay under solvent-free reaction condition has been proposed. The catalysts were prepared by incipient wetness impregnation method. The physicochemical characterizations of the HPV (20%) supported on natural clay (HPVAC-20) have also been discussed. Solvent-free heterogeneous reaction condition, simple workup procedure, short reaction time, high yield of products, and reusability of the catalyst are the advantages of the protocol.     

Facile synthesis of bis(indolyl)methanes using catalytic amount of iodine at room temperature under solvent-free conditions

Efficient electrophilic substitution reactions of indoles with various aromatic aldehydes were carried out using a catalytic amount of I₂ under solvent-free conditions to afford the corresponding bis(indolyl)methanes in excellent yields.     

Synthesis of bis(indolyl)methanes under catalyst-free and solvent-free conditions

Abstract

Condensation of indole with aromatic aldehydes has been carried out without using any catalyst and solvent to give bis(indolyl)methanes.     

An efficient and clean synthesis of bis(indolyl)methanes in a protic solvent at room temperature

Electrophilic substitution reactions of indoles with various aldehydes were carried out in a protic solvent at room temperature in the absence of any other catalyst to afford bis(indolyl)-methanes in excellent yields.     

Base-promoted three-component cascade approach to unsymmetrical bis(indolyl)methanes

Here we report a base-catalyzed reaction of two different indoles with aldehydes under heating to produce unsymmetrical bis(indolyl)methanes (BIMs), in which one of the indole ring must be N-substituted. Mixture of EtOH-H₂O is used as solvent. The reaction did not give symmetrical BIMs of N-substituted indoles or N–H indoles. However, traces of latter were formed in few cases, especially when electron-rich aldehydes were used. Diversely substituted indoles and aldehydes were used for the reaction. The reaction proceeds via 3-indolylalcohol, which we confirmed through isolation. The method also gives good yield on multigram scale reaction.     

Surfactant-assisted synthesis of bis(indolyl)methanes in water

An environmentally friendly synthesis method for bis(indolyl)methanes has been developed in the presence of sodium lauryl ether sulfate(SLES),electrophilic substitution reactions of indoles with aldehydes were accomplished in water as solvent at room temperature without any Bronested or Lewis acid catalysts.     

Molecular iodine-catalyzed efficient and highly rapid synthesis of bis(indolyl)methanes under mild conditions

Highly rapid and efficient electrophilic substitution reactions of indoles with various aldehydes and ketones were carried out using I₂ in CH₃CN to afford the corresponding bis(indolyl)methanes in excellent yields.     

Efficient synthesis of bis(indolyl)methanes catalyzed by(PhCH2PPh3)+Br3-under solvent-free conditions

<正>Benzyltriphenylphosphonium tribromide(BTPTB) has been applied as an efficient catalyst for the preparation of bis(indolyl)-methanes (BIMs) via electrophilic substitution of indoles with aldehydes in the absence of solvent.     

Silica supported perchloric acid (HClO4-SiO2): a green,reusable, and highly efficient heterogeneous catalyst for the synthesis of thioethers under solvent-free conditions at room temperature

Abstract

A highly efficient and clean procedure is described for the synthesis of thioethers with excellent yields under solvent-free conditions at room temperature using a catalytic amount of HClO₄-SiO₂. The catalyst is easily prepared, stable, and reusable without much loss of catalytic activity, and is efficient under the reaction conditions.     

Synthesis of Bis(indolyl) Methanes in Catalyst- and Solvent-Free Reaction

Efficient synthesis of bis(indolyl) methanes by the reaction of indoles with various carbonyl compounds in the absence of catalyst and solvent afforded the corresponding bis(indolyl) methanes in excellent yields.     

CuBr2‐Catalyzed Synthesis of Bis(indolyl)methanes

Abstract

Copper(II) bromide is found to be an efficient catalyst for the electrophilic substitution reaction of indole with aldehydes to afford the corresponding bis(indolyl)methanes in good yields.     

A versatile and practical synthesis of bis(indolyl)methanes/bis(indolyl)glycoconjugates catalyzed by trichloro-1,3,5-triazine

A practical and efficient electrophilic substitution reaction of indoles with a variety of aldehydes was carried out using catalytic trichloro-1,3,5-triazine (10 mol %) in acetonitrile to furnish the corresponding bis(indolyl)methanes in excellent yields. Similarly, sugar derived aldehydes gave hitherto unknown bis(indolyl)glycoconjugates in very good yields.     

Ionic liquid promoted synthesis of bis(indolyl) methanes

1-benzyl-3-methyl imidazolium hydrogen sulphate [bnmim][HSO₄] was found to be an effective catalyst for the condensation reaction of indoles and derivatives with benzaldehydes in microwave irradiation with lower reaction time and higher yields to give bis(indolyl) methanes.      

Synthesis,antibacterial and anti-inflammatory activity of bis(indolyl)methanes

A series of bioactive bis(indolyl)methanes are synthesized by one-pot green reaction of indole with various substituted aldehydes by microwave irradiation under solvent free conditions. The antibacterial activity against Staphylococcus aureus and anti-inflammatory activity of the synthesized bis(indolyl)-methanes are evaluated in vitro and compared to standard drugs tetracycline and diclofenac, respectively. The majority of the compounds showed good antibacterial and anti-inflammatory activity. Interestingly, compounds 3j, 3i, 3k and 3g exhibited much higher anti-inflammatory activity than the standard diclofenac drug and thus qualify for clinical trials to be used as an anti-inflammatory compound.     

Novel method for synthesis of unsymmetrical bis(indolyl)alkanes catalyzed by ceric ammonium nitrate (CAN) under ultrasonic irradiation

The reaction of indole with (1H-indol-3-yl)(alkyl) methanol was catalyzed efficiently by ceric ammonium nitrate under ultrasonic irradiation to afford the unsymmetrical bis(indolyl)alkane in good to excellent yields.     

Diversity-oriented TsOH catalysis-enabled construction of tanshinone-substituted bis(indolyl/pyrrolyl)methanes and their biological evaluation for anticancer activities

We have developed an efficient and straightforward methodology for the synthesis of novel tanshinone-substituted bis(indolyl/pyrrolyl)methane scaffolds 3 through TsOH catalysis-enabled addition of indoles or pyrroles 1 with tanshinones 2 based on molecular hybridization strategy. Products were smoothly obtained in good yields (up to 81% yield). This protocol also represents the first construction of tanshinone skeleton-fused bis(indolyl/pyrrolyl)methane scaffolds, thus leading to new knowledge in the fields of both molecular complexity and diversity-oriented synthesis and the lead compound discovery. Furthermore, their biological activities against human leukemia cells K562, human prostate cancer cells PC-3, and human lung cancer cells A549 have been preliminarily demonstrated by in vitro assays. The results demonstrated that most of these compounds 3 obtained by this protocol showed comparable activity to the positive control of cisplatin.     

Antimony Trichloride Catalyzed Condensation of Indole and Carbonyl Compounds: Synthesis of Bis(indolyl)methanes

A mild and efficient condensation reaction of indoles with various aldehydes and ketones under catalysis of antimony trichloride (SbCl₃) afforded biologically important bis(indolyl)methanes in good yield. The structures of all the newly synthesized compounds were elucidated on the basis of IR, ¹H NMR and mass spectral data.     

Synthesis of bis(indolyl)methanes using silica gel as an efficient and recyclable surface

Here we describe a simple, clean, and efficient solvent-free protocol for the synthesis of bis(indolyl)methanes promoted by silica gel. The products were obtained in good to excellent yields through the reaction of indoles with cyclohexanone and a range of aldehydes. The silica gel was easily recovered and utilized for further reactions without loss of activity.     

Glycerin and CeCl3·7H2O: a new and efficient recyclable medium for the synthesis of bis(indolyl)methanes

Glycerin and CeCl₃·7H₂O were successfully used in recyclable catalytic system for the synthesis of several bis(indolyl)methanes in good to excellent yields through the reaction of indoles with aldehydes. The method is applicable to aliphatic and aromatic aldehydes, and the mixture of glycerin and CeCl₃·7H₂O can be reused up to five times without special treatment and with comparable yields.