A new practical synthesis of triaryl and trisindolylmethanes under solvent-free reaction conditions

An efficient and practical synthesis of triaryl and trisindolylmethanes is reported via the bisarylation of aryl aldehydes with activated arenes. The new method features mild solvent-free reaction conditions, in most cases nearly stoichiometric reagent ratios, catalytic amount of the readily available, easily-handled, recoverable and reusable Br?nsted acid catalyst o-benzenedisulfonimide.     

Efficient and one‐pot catalytic synthesis of 2‐imidazolines and bis‐imidazolines with p‐toluenesulfonic acid under solvent free conditions

A practical, efficient, and inexpensive method for the synthesis of 2‐imidazoline from the reaction of nitriles with ethylenediamine or 1,2‐propanediamine using p‐toluenesulfonic acid or pyridinium p‐toluenesulfonate under reflux conditions is reported. This catalyst can be successfully applied for the chemoselective conversion of dicyanobenzenes to corresponding mono‐ and bis‐imidazolines. The applications of these catalysts are feasible because of easy preparation, easy handling, stability, inexpensive, good activity, and eco‐friendly. J. Heterocyclic Chem., (2011).     

A new biarylphosphine ligand for the Pd-catalyzed synthesis of diaryl ethers under mild conditions

A new bulky biarylphosphine ligand (L8) has been developed that allows the Pd-catalyzed C-O cross-coupling of a wide range of aryl halides and phenols under milder conditions than previously possible. A direct correlation between the size of the ligand substituents in the 2', 4', and 6' positions of the nonphosphine containing ring and the reactivity of the derived catalyst system was observed. Specifically, the rate of coupling increased with the size of these substituents.     

A new method for the synthesis of cinnamonitriles by catalytic olefination

Catalytic olefination of hydrazones of aromatic aldehydes with dibromoacetonitrile affords cinnamonitriles.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 247–249, January, 2005.     

A convenient one‐pot method for the synthesis of symmetrical dialkyl trithiocarbonates using NH4OAc under mild neutral conditions

A facial, new, one‐pot method for the preparation of symmetrical organic trithiocarbonates from various alkyl halides and carbon disulfide is described. This is a convenient, clean, and mild procedure, which involves the use of the neutral, nontoxic, commercially available, and inexpensive reagent NH₄OAc in the preparation of the trithiocarbonate ion from carbon disulfide.     

A mild method for extracting amines under neutral conditions

Copper (II) ion-exchanged zeolites are highly active reagents for selective complexation of amines in aqueous or organic solution.     

Kinetics of synthesis of bis‐(benzoxazolyl‐2‐methyl) sulfide under phase‐transfer catalysis conditions

Kinetics of synthesis of bis‐(benzoxazolyl‐2‐methyl) sulfide (BBMS) is investigated under phase‐transfer catalysis conditions. Thus, the reaction of 2‐chloromethylbenzoxazole and sodium sulfide is carried out in a two‐phase (organic/water) medium, and quaternary ammonium salt and quaternary phosphonium salt are used as phase‐transfer catalyst (PTC) in the reaction. The conversion of 2‐chloromethylbenzoxazole is dramatically enhanced by adding a small quantity of PTC and is also greatly affected by the reaction conditions. The effects of various reaction variables on the kinetics are investigated, including the amount of catalyst, the temperature, the kinds of catalysts, the kinds of solvents, and the agitation speed. An interfacial reaction mechanism is proposed to explain the characteristics of the reaction. A pseudo‐first‐order rate model is established to describe the relationship between the fractional conversion and the reaction time. The kinetics data demonstrate that the model is suitable to the reaction of synthesis of BBMS. © 2009 Wiley Periodicals, Inc. Int J Chem Kinet 41: 296–302, 2009     

A new catalytic method for the synthesis of boroxanes

A new Ru-H complex catalyzed O-borylation of boronic acids with vinylboronates leading to boroxane bond formation with evolution of ethylene is described. Under the optimum conditions, when [Ru(CO)Cl(H)(PPh₃)₃] and excess vinylboronate are used, the reaction gives exclusively the corresponding boroxane in high yield. The proposed mechanism of catalysis is supported by the results of the equimolar reaction of Ru-B complex with 1,3,2-dioxaborinan-2-ol.     

A new mild method for the one-pot synthesis of pyridines

Polysubstituted pyridines are prepared in good yield and with total regiocontrol by the one-pot reaction of an alkynone, 1,3-dicarbonyl compound and ammonium acetate in alcoholic solvents. This new three-component heteroannulation reaction proceeds under mild conditions in the absence of an additional acid catalyst and has been used in the synthesis of dimethyl sulfomycinamate, the acidic methanolysis degradation product of the sulfomycin family of thiopeptide antibiotics.     

An efficient one‐pot synthesis of bis‐indolylmethanes containing pyrazolyl catalyzed by Brønsted acidic ionic liquid under solvent‐free conditions

Brønsted acidic ionic liquid [PyNCH₂CO₂H][HSO₄] was found to be an effective catalyst for the condensation reactions of indoles with various 4‐formylpyrazoles to afford the corresponding bis‐indolylmethanes containing pyrazole under solvent‐free conditions. The satisfactory results were obtained with excellent yields, short reaction time, and simplicity in the experimental procedure. J. Heterocyclic Chem., (2011).     

Bulk and supported tungstophosphoric acid as friendly,efficient, recyclable catalysts for the synthesis of bis‐indolylmethanes under solvent‐free conditions

The treatment of indole with structurally diverse aldehydes in the presence of catalytic amount of inorganic‐supported polyoxometalates, heterogeneous, reusable and efficient catalysts at room temperature gave the corresponding bis‐indolylmethanes in excellent yields and shorter reaction times under solvent‐free conditions. The catalyst can be reused for several times, but it will be less active. © 2009 Wiley Periodicals, Inc. Heteroatom Chem 20:325–331, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20554     

Claycop/hydrazine: A new and highly efficient recyclable/reusable catalytic system for 1,4‐disubstituted‐1,2,3‐triazole synthesis under solvent‐free conditions

Clay‐supported copper(II) nitrate (claycop) has been used as an efficient catalyst for azide–alkyne cycloaddition reactions leading to 1,4‐disubstituted 1,2,3‐triazoles. The highly efficient claycop/hydrazine hydrate catalytic system affords triazoles in a few minutes (1–20 min) at room temperature, under mild and solvent‐free conditions. High regioselectivity, excellent yields, ease of claycop synthesis and recyclability/reusability of the catalyst are considered as practical merits of the protocol.     

Catalytic synthesis of cyclic carbonates from epoxides and carbon dioxide by magnetic UiO‐66 under mild conditions

The catalytic activity of UiO‐66@Fe₃O₄@SiO₂ catalyst was investigated in the fixation of carbon dioxide with epoxides under mild conditions. In this manner, a facile magnetization of UiO‐66 was achieved simultaneously by simply mixing this metal–organic framework and silica‐coated Fe₃O₄ nanoparticles in solution under sonication. The prepared catalyst was characterized using Fourier transform infrared and UV–visible spectroscopies, X‐ray diffraction, transmission and field emission scanning electron microscopies, N₂ adsorption and inductively coupled plasma atomic emission spectroscopy. This new heterogeneous catalyst was applied as a highly efficient catalyst in the coupling of carbon dioxide with epoxides at mild temperatures and pressures. Furthermore, it could be easily recovered with the assistance of an external magnetic field and reused three consecutive times without significant loss of activity and mass.     

Theoretical study of catalytic dinitrogen reduction under mild conditions

Density functional theory results on key steps of Schrock's catalytic cycle are presented. The quantum chemical modeling of the dinitrogen-reducing reaction steps is conducted without simplifying the bulky HIPT [HIPT = 3,5-(2,4,6-iPr(3)C(6)H(2))(2)C(6)H(3)] substituents at the triamidoamine ligand.     

Homolytic alkylation of some 3,4‐quinolinediyl bis‐sulfides under minisci reaction conditions

Reaction of hydrogen sulfate of 3,4‐quinolinediyl bis‐sulfides 1a , 2a , 3a , and 4a with isopropyl and cyclohexyl radicals formed from alkyl iodide/hydrogen peroxide/DMSO/Fe⁺⁺ salt system took place at α‐quinolinyl position and led to the respective mono‐ and dialkyl derivatives 1b‐e , 2b‐e , 3b,c , and 4b,c . Action of sodium methoxide towards isopropyl derivatives 1b,c and 2b,c caused the 1,4‐dithiin ring opening to form (after S‐methylation) derivatives of 3,4′‐ and 3,3′‐diquinolinyl sulfides 6a,b and 7a,b .     

A stereoselective three‐component reaction: One‐pot synthesis of cis‐isoquinolonic acids catalyzed by silica sulfuric acid under mild and heterogeneous conditions

A mild and stereoselective three‐component one‐step synthesis of cis‐isoquinolonic acid using silica sulfuric acid as a heterogeneous catalyst from an aldehyde, amine and homophthalic anhydride in acetonitrile is described. This new method produces pure products in high yields (81‐91%).     

A highly efficient Pd-C catalytic hydrogenation of pyridine nucleus under mild conditions

A synergistic Pd-C catalytic hydrogenation of 4-pyridinecarboxamides straightforward to 4-piperidinecarboxamide hydrochlorides was developed in the presence of ClCH₂CHCl₂. It provided a novel strategy for highly efficient hydrogenation of pyridine nuclear by using low-cost Pd-C catalyst under mild conditions.     

Melamine–formaldehyde resin supported H a mild and inexpensive reagent for synthesis of coumarins under mild conditions

Melamine-formaldehyde resin supported H~+ is used as an efficient catalyst in the Pechmann condensation reaction of phenols withβ-ketoesters,in solvent-free media leading to the formation of coumarin derivatives using conventional heating and microwave irradiation in excellent yields with good purity.     

A catalytic system for the selective conversion of cellulose to 5-hydroxymethylfurfural under mild conditions

Russian Chemical Bulletin - Conversion of cellulose to 5-hydroxymethylfurfural (5-HMF), one of the most promising products derived by conversion of renewable raw materials, has been studied. When...