Microwave-assisted heteropolyanion-based ionic liquids catalyzed transamidation of non-activated carboxamides with amines under solvent-free conditions

An environmentally benign and highly efficient protocol for the transamidation of non-activated carboxamides with amines using heteropolyanion-based ionic liquids as catalysts under microwave-assisted and solvent-free conditions has been developed. As evaluated by the reactions of a structurally diverse set of amides and amines, the scope and utility of the transamidation proved to be quite general. Operational simplicity, solvent-free media, the potential reusability of catalysts and wide functional group tolerance are attractive features. This method provides a much improved protocol over the existing methods.     

Efficient method for the direct preparation of amides from carboxylic acids using tosyl chloride under solvent-free conditions

A simple, clean and highly efficient solvent-free procedure for the preparation of primary, secondary, tertiary and aromatic amides is described from the direct reaction of carboxylic acids and silica-supported ammonium salts, triethylamine (TEA) and tosyl chloride (TsCl) as condensing agent. The reaction proceeds rapidly in high yields at room temperature.     

Highly efficient three-component Strecker-type reaction catalyzed by MgI2 etherate under solvent-free conditions

A concise, straightforward and efficient method has been developed for the synthesis of α-aminonitriles by an one-pot three-component condensation of aldehydes or ketones, amines and trimethylsilyl cyanide catalyzed by MgI₂ etherate under solvent-free conditions. This protocol has some advantages such as mild reaction condition, simple work-up, short reaction time and high product yields.     

Protic guanidinium ionic liquid as a green and highly efficient catalyst for the synthesis of functionalized spirochromenes under solvent-free conditions

A simple and efficient method for the synthesis of functionalized spirochromenes is explained using protic guanidinium ionic liquid as a catalyst under solvent-free conditions at room temperature. This procedure is simple, clean, and excellent yields are obtained in short reaction times.     

One-pot synthesis of various xanthene derivatives using ionic liquid 1, 3-disulfonic acid imidazolium hydrogen sulfate as an efficient and reusable catalyst under solvent-free conditions

In this study, 1,3-disulfonic acid imidazolium hydrogen sulfate （DSIMHS） is used as an efficient and reusable ionic liquid for the green, mild, and efficient synthesis of xanthenes under solvent-free conditions. Simple and easy work-up, low cost, green process, short reaction times and excellent yields of the products are the advantages of this procedure. Further, the catalyst can be recycled and reused at least for four times without a noticeably decrease in its catalytic activity.     

Efficient microwave-assisted direct C-benzoylation of phenols and naphthols with benzoic acid catalyzed by bismuth triflate under solvent-free or ionic liquid conditions

An efficient and simple route for the synthesis of ortho-hydroxyaryl ketones has been developed. The microwave-assisted direct C-benzoylation of phenols and naphthols in the presence of metal triflates afforded the corresponding ortho-hydroxyaryl ketones in moderate to excellent yields. Bismuth triflate showed the best catalytic performance compared to other metal triflates. The protocol has advantages including short reaction times, high chemoselectivity towards C-acylation, and simple work-up. Additionally, bismuth triflate can be easily recovered and reused several times without significant loss of catalytic performance.     

Immobilized ionic liquid on superparamagnetic nanoparticles as an effective catalyst for the synthesis of tetrasubstituted imidazoles under solvent-free conditions and microwave irradiation

The ionic liquid 1-methyl-3-(3-trimethoxysilylpropyl) imidazolium chloride was immobilized on superparamagnetic Fe₃O₄ nanoparticles (IL-MNPs) and used as an efficient heterogeneous catalyst for the one-pot synthesis of 1,2,4,5-tetrasubstituted imidazoles under solvent-free conditions using microwave irradiation. The reactions in conventional heating conditions were compared with the microwave-assisted reactions. The combined merits of microwave irradiation and immobilized ionic liquid on superparamagnetic nanoparticles make the four-component condensation with safe operation, low pollution, and rapid access to products and simple work-up.     

An efficient and green preparation of 5-aminophosphonate substituted pyrimidine nucleosides under solvent-free conditions

<正>An environmentally benign and highly efficient one-pot preparation ofα-aminophosphonates under solvent-free conditions was developed.By employing this method,5-aminophosphonate substituted pyrimidine nucleosides were synthesized in good to excellent yields starting from 5-formyl-2'-deoxyuridine,aniline and dimethylphosphite.     

Selenonium ionic liquid as an efficient catalyst for the synthesis of thioacetals under solvent-free conditions

Acidic ionic liquid butyl ethyl phenyl selenonium tetrafluoroborate, [BEPSe]BF₄, was successfully employed as a catalyst for the synthesis of several dithioacetals in the absence of a solvent. The method is general and selectively afforded thioacetals derived from aldehydes and ketones in good yields.     

无溶剂条件下碳基固体酸催化一锅法合成酰胺烷基萘酚(英文)

An efficient, environmentally friendly procedure for the synthesis of amidoalkyl naphthols through the one‐pot, three‐component reaction of β‐naphthol, aryl aldehydes, and acetamide in the presence of a carbon‐based solid acid under thermal solvent‐free conditions is described. The beneficial fea-tures of this new synthetic approach include short reaction time, high yields, clean reaction profiles, and a simple work‐up procedure. Furthermore, the catalyst can be readily recycled and reused four times without obvious significant loss of activity. The structure of the catalyst was confirmed by Fourier transform infrared spectroscopy, N2 adsorption/desorption analysis, and X‐ray diffraction.     

An efficient procedure for the synthesis of coumarin derivatives using TiCl4 as catalyst under solvent-free conditions

The ability of titanium(IV) chloride as a catalyst to promote the Pechmann condensation reaction with a range of phenols and β-keto esters is described.The reaction was carried out by addition of TiCl₄ to a mixture of the phenol and the β-keto ester with thorough stirring in the absence of a solvent and represents an improvement on the classical Pechmann conditions. The yields of coumarins obtained via this novel protocol were significantly higher than those using the conventional method and the reaction duration was reduced to a few minutes or even a few seconds.     

Catalysis by ionic liquids: cyclopropyl carbinyl rearrangements catalyzed by [pmim]Br under organic solvent free conditions

Aryl substituted cyclopropyl carbinol derivatives undergo stereoselective rearrangements catalyzed by the ionic liquid, 1-methyl-3-pentylimidazolium bromide, under sonication, without any organic solvent, to produce the substituted conjugated all-trans-butadienes.     

Highly efficient aza-Michael reactions of aromatic amines and N-heterocycles catalyzed by a basic ionic liquid under solvent-free conditions

A task-specific basic ionic liquid, [Bmim]OH, has been introduced as a catalyst for the aza-Michael addition of aromatic amines and N-heterocycles to cyclic or acyclic ketones under neat conditions. The catalyst can be recycled for subsequent reactions without any appreciable loss of efficiency.     

Simple and practical procedure for Knoevenagel condensation under solvent-free conditions

The Knoevenagel condensation reaction between araldehyde and active methylene using gallium chloride catalyst under solvent-free conditions has been described. The reaction takes place at room temperature by grind stone method and offers good purity of product in high yield. Work-up is very simple and the products do not need further purification. The reaction conditions are very mild and this protocol is applicable to various aldehydes such as araldehydes and heteroaromatic aldehydes as well as active methylene compounds, namely, malononitrile or ethyl cyanoacetate.

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A simple,efficient and green procedure for Michael addition catalyzed by [C_4dabco]OH ionic liquid

A dabco-based basic ionic liquid,1-butyl-4-aza-1-azaniabicyclo[2.2.2]octane hydroxide,has been developed as a catalyst for a convenient and rapid method for the Michael addition of active methylene compounds to a b-unsaturated carboxylic esters and nitriles.The method is very simple,and the yields are very high.The catalyst can be recycled several times without much loss of activity.     

乙酸功能化离子液体作为高效、可回收的催化剂用于2-萘酚与芳醛缩合反应(英文)

An efficient solvent‐free protocol for the synthesis of 14‐aryl‐14H‐dibenzo[a,j]xanthenes from the condensation of 2‐naphthol with arylaldehydes, using acetic acid functionalized imidazolium salts (1‐carboxymethyl‐3‐methylimidazolium bromide ([cmmim]Br) and 1‐carboxymethy1‐3-me-thylimidazolium tetrafluoroborate([cmmim]BF4) as reusable catalysts, has been developed. The turn over frequency on the catalysts is several times higher than the other previously reported catalysts. Also, thermal gravimetric analysis and powder X‐ray diffraction pattern of the catalysts have been studied.     

An efficient and novel method for the synthesis of sulfinate esters under solvent-free conditions

The present letter describes a reliable one-stage process for the preparation of sulfinate esters from the corresponding sulfinic acid and alcohols in the presence of N,N′-dicyclohexylcarbodiimide (DCC) under solvent-free conditions.     

Iron catalyzed Michael addition: Chloroferrate ionic liquids as efficient catalysts under microwave conditions

The iron containing ionic liquid 1-butyl-3-methylimidazolium tetrachloroferrate ([C4mim]Cl/FeCl3; = 0.5) proved to be an efficient catalyst for the solvent-free metal catalyzed Michael addition of β-keto esters and enones. Due to the ionic structure of the catalyst, a significant acceleration of the reaction rate was observed under microwave conditions. Furthermore, recycling of the ionic liquid catalyst could be performed after simply distilling off the products.     

Pyrrole synthesis in ionic liquids by Paal-Knorr condensation under mild conditions

Paal-Knorr condensation of 2,5-hexandione with primary amines was successfully carried out in ionic liquids. Through investigating different ionic liquids, different reaction times, the reaction, using ionic liquids as solvent, exhibited simple product isolation procedure, improved yields and exclusive selectivity and the mild conditions and the avoidance of using toxic catalysts are also its special features. Recovery and reuse of ionic liquid are also satisfactory.     

Methanolysis of poly(lactic acid) (PLA) catalyzed by ionic liquids

Poly(lactic acid) (PLA) was depolymerized by methanol in the presence of a novel catalyst: ionic liquids. It was found that the purification method of the main products in the methanolysis catalyzed by ionic liquids was simpler than that of traditional compounds, such as sulfuric acid. Qualitative analysis indicated that the main product in the methanolysis process was methyl lactate. The influences of experimental parameters, such as the amount of ionic liquids, methanolysis time, reaction temperature, and dosages of methanol on the conversion of PLA, yield of methyl lactate were investigated. Under the optimum conditions, using ionic liquid 1-butyl-3-methylimidazolium acetate ([Bmim][Ac]) as catalyst, results showed that the ionic liquid could be reused up to 6 times without apparent decrease in the conversion of PLA and yield of methyl lactate. The kinetics of the reaction was also investigated. The results indicated that the methanolysis of PLA was a first-order kinetic reaction with activation energy of 38.29 kJ/mol. In addition, a possible catalysis mechanism of the methanolysis of PLA was proposed.