A practical synthesis of bis(indolyl)methanes catalyzed by BF_3·Et_2O

Practical BF3Et2O catalyzed reactions between indoles and a series of carbonyl compounds at room temperature are described, which afford bis(indolyl)methanes with isolated yields up to 96%.     

An effective lactic acid-modified Hβ zeolite for synthesis of bis(indolyl)methanes

Excellent activity and stability have been observed for a lactic acid-modified Hβ (LA-Hβ) zeolite in the synthesis of bis(indolyl)methanes by Friedel–Crafts alkylation of indole with aldehydes. It is proposed that lactic acid treatment is appropriate for dealumination of Hβ zeolite, and results in a LA-Hβ zeolite with greater surface area, fewer weak acid sites, and more moderately-strong acid sites, as confirmed by the Brunauer–Emmett–Teller method, inductively coupled plasma emission spectrometry, and temperature-programmed desorption of NH₃. Moreover, both electronic and steric effects of substituents on the aromatic ring of the aldehydes were found to be important in this reaction.     

Synthesis of bis(indolyl) methanes catalyzed by Schiff base-Cu(Ⅱ) complex

Schiff base-Cu(Ⅱ) complex is found to be an effective catalyst for the condensation reaction of indole with aldehydes using ethanol as the solvent.The characterization of the catalysts was carried out using XRD and FT-IR.     

A facile synthesis of α-aminophosphonates catalyzed by ytterbium perfluorooctanoate under solvent-free conditions

Three-component reactions of aldehydes, amines and diethyl phosphite are efficiently catalyzed by ytterbium perfluorooctanoate [Yb(PFO)₃] under solvent-free conditions, giving the corresponding α-aminophosphonates in good to excellent yields. The catalyst can be recovered and reused for several times without any significant loss of activity. Furthermore, a possible mechanism for this transformation is also presented.     

Polyvinylsulfonic acid as a novel Brønsted acid catalyst for the synthesis of bis(indolyl)methanes

Abstract

Polyvinylsulfonic acid as a novel, biodegradable, and efficient Brønsted acid catalyst for the reaction of indoles with aldehydes to obtain bis(indolyl)methanes has been reported. The catalyst exhibited remarkable activity, recyclability, and tolerated a wide variety of functional groups providing the desired bis(indolyl)methanes in excellent yield (64–96%) at room temperature using ethanol as a solvent. The effect of different reaction parameters like solvent, temperature, catalyst doses, and recyclability were investigated for the title reaction.     

A facile synthesis of α,α′-bis(substituted benzylidene) cycloalkanones catalyzed by p-TSA under solvent-free conditions

Abstract

Various 2,6-dibenzylidene cycloalkanones were readily prepared in a few minutes with good yields by simply mixing aromatic aldehydes with cycloalkanones in the presence of catalytic amounts of p-toluenesulfonic acid as a solid heterogeneous catalyst under solvent-free condition.     

Bi(NO3)3 · 5H2O mediated synthesis of 4,4′-diaminotriarylmethane leuco malachite compounds under solvent-free conditions

In this report, we described the synthesis and characterization of a variety of diaminotriarylmethane derivatives with dimethylamino functional groups. These compounds were synthesized by the tandem regio-selective electrophilic aromatic substitution reaction of N,N-dimethylaniline with aryl aldehydes to form the corresponding diaminotriarylmethane compounds. In our strategy, Bi(NO₃)₃ was used as a catalyst under solvent free conditions to afford the desired products in good to excellent yields.      

Molybdenum trioxide catalyzed oxidative cross-dehydrogenative coupling of benzylic sp3 C–H bonds: synthesis of α-aminophosphonates under aerobic conditions

Molybdenum trioxide (MoO₃) catalyzed efficient oxidative cross-dehydrogenative-coupling (CDC) method for C–H functionalization of N-aryl tetrahydroisoquinolines has been explored. This user-friendly method of synthesizing α-aminophosphonates employs 1.1 equiv of dialkyl-H-phosphonate under aerobic condition. Formation of new C–P bonds from unfunctionalized starting materials under environmentally benign conditions provides an excellent avenue for the synthesis of biologically active α-aminophosphonates.     

Synthesis of Bis(indolyl)methanes using a Catalytic Amount of ZnO under Solvent‐Free Conditions

Efficient electrophilic substitution reactions of indoles with various aromatic aldehydes were carried out using a catalytic amount of ZnO under solvent‐free conditions to afford the corresponding bis(indolyl)methanes in excellent yields. Among the various methods published for the synthesis of bis(indolyl)methane, ZnO is a very cheap, environmentally friendly, and reusable catalyst that can be used for synthesis of a new range of bis(indolyl)methane derivatives.     

FeCl3·6H2O catalyzed diastereoselective synthesis of (L)-menthyl 4-oxo-2-arylpiperidine-3-carboxylates

An efficient diastereoselective synthesis of substituted piperidines is accomplished by using catalytic amount of FeCl₃·6H₂O via intramolecular aza-Michael addition of carbamate on alkylidene β-keto (L)-menthyl esters in a very short time.     

Facile Synthesis of Bis(indolyl)methanes Using LaCl3 · 7H2O as a Mild and Efficient Catalyst in Molten Salt Media

Efficient electrophilic substitution reaction of indole with various carbonyl compounds were carried out using a catalytic amount of LaCl₃ · 7H₂O in molten tetraethylammonium chloride as an ionic liquid to afford the corresponding bis(indolyl)methanes in excellent yields.     

Microwave-promoted total synthesis of N-(α-hydroxybenzyl)formamides using DMSO/H2O under neutral conditions

A total synthesis route toward N-(α-hydroxybenzyl)formamides by microwave-assisted reaction of dichloroaziridines and aqueous dimethyl sulfoxide is described. The corresponding products were obtained in excellent yields with reduced reaction times. The obtained formamides were characterized by various techniques such as Infra red (IR), Nuclear Magnetic Resonance (NMR) and mass spectroscopy data.     

Ruthenium(Ⅲ) chloride as an efficient catalyst for the synthesis of perimidine derivatives under mild conditions

Various biologically important perimidine derivatives have been synthesized efficiently from various ketones and naphthalene1,8-diamine by using a catalytic amount of RuC13 (1 mol%). This method is a very simple and high yielding reaction for the synthesis of perimidine derivatives.     

Glycerol assisted eco-friendly strategy for the facile synthesis of 4,4′-(arylmethylene)bis(3-methyl-1H-pyrazol-5-ols) and 2-aryl-2,3-dihydroquinazolin-4(1H)-ones under catalyst-free conditions

Research on Chemical Intermediates - This article describes glycerol mediated eco-friendly approaches for the convenient access of structurally diverse...     

One-pot conversion of aromatic compounds to the corresponding bis(indolyl)methanes by the Vilsmeier–Haack reaction

Various electron-rich aromatics could be smoothly converted into the corresponding bis(indolyl)methanes in good to moderate yields by treatment of electron-rich aromatics with POCl₃ and DMF, followed by treatment with indole at room temperature. The present article is the first report on a novel metal-free one-pot method for the preparation of bis(indolyl)methanes from electron-rich aromatics.     

Dimethylformamide as a convenient CO source for the facile preparation of rhodium-, iridium- or ruthenium-chlorocarbonyl complexes directly from RhCl3·3H2O,IrCl3·3H2O or RuCl3·3H2O

The anionic complexes [RhCl₂(CO)₂]⁻, [IrCl₂(CO)₂]⁻ or [RuCl₃(CO)₂(DMF)]⁻ can be obtained in high yields (up to 85 %) and in less than 60 min by refluxing dimethylformamide solutions of RhCl₃·3H₂O, IrCl₃·3H₂O or RuCl₃·3H₂O. Depending on the metal, the presence of small amounts of water and/or hydro- chloric acid greatly accelerates the reduction step. For rhodium, several intermediates have been trapped which allow us to propose a mechanism for this reaction.     

Combinatorial synthesis and characterization of metal-open frameworks in mild and friendly conditions: application to CO₂ adsorption

Combinatorial screening using precipitation methods at room temperature can lead to a great diversity of carboxylate based Metal Organic Frameworks (MOFs) including already known or original porous solids. The investigation of the synthesis of MOFs in different solvent and solvent mixtures includes the use of solvents such as alcohols and tetrahydrofuran (THF) which would greatly facilitate large scale production. We also show the application of Principal Component Analysis (PCA) and clustering techniques on large libraries of XRD diffraction files in order to identify classes of similar phases and peculiar phases. The combinatorial screening of 105 samples in the La/btc system has led to the identification of two phases which are solvent depending. On the La(btc) compound, the CO? adsorption measurements reveal a guest-host interactions as supported by XRD phase transformation upon thermal treatment. The mass transport can be assigned to a "single file diffusion" regime due to the one dimensional channel porous structure associated to small pore size.     

Macrocycles and medicine – facile synthesis of a bis(macrocycle) with pendent functionality

The crystal structure of the Cu(II) perchlorate complex of a functionalised bis(macrocycle) ligand, where the individual macrocycle units are of the cyclam type and adopt the trans-III configuration, is analysed in terms of its possible relationship to those of bis(macrocycle) complexes possessing anti-viral activity. To cite this article: P.V. Bernhardt et al., C. R. Chimie 8 (2005).     

Kinetic study of oxygen adsorption over nanosized Au/γ-Al₂O₃ supported catalysts under selective CO oxidation conditions

O? adsorption is a key process for further understanding the mechanism of selective CO oxidation (SCO) on gold catalysts. Rate constants related to the elementary steps of O? adsorption, desorption and surface bonding, as well as the respective activation energies, over a nanosized Au/γ-Al?O? catalyst, were determined by Reversed-Flow Inverse Gas Chromatography (RF-IGC). The present study, carried-out in a wide temperature range (50-300 °C), both in excess as well as in the absence of H?, resulted in mechanistic insights and kinetic as well as energetic comparisons, on the sorption processes of SCO reactants. In the absence of H?, the rate of O? binding, over Au/γ-Al?O?, drastically changes with rising temperature, indicating possible O? dissociation at elevated temperatures. H? facilitates stronger O? bonding at higher temperatures, while low temperature binding remains practically unaffected. The lower energy barriers observed, under H? rich conditions, can be correlated to O? dissociation after hydrogenation. Although, H? enhances both selective CO reactant's desorption, O? desorption is more favored than that of CO, in agreement with the well-known mild bonding of SCO reactant's at lower temperatures. The experimentally observed drastic change in the strength of CO and O? binding is consistent both with well-known high activity of SCO at ambient temperatures, as well as with the loss of selectivity at higher temperatures.