Search

The efficient synthesis of novel fused pyridines via the three component condensation of aldehydes, kojic acid, and 6-amino-1,3-dimethyluracil, catalyzed by the ionic liquid aminopropyl-1,3,5-triazine-2,4-diphosphonium hydrogen sulfate supported on functionalized nano-silica, under solvent-free conditions is reported. Additionally, bis-derivatives of these compounds were smoothly synthesized from dialdehydes. This method has the advantages of mild conditions, high yields, short reaction times, easy work-up, and being environmentally friendly. Moreover, the catalyst can be easily separated from the reaction mixture, recycled, and reused several times without a noticeable decrease in catalytic activity.

An efficient and facile method for the synthesis of 2-arylindoles, 2-arylimidazo[1,2-a]pyridines and 2-arylquinoxalines by the reaction of various α-bromo ketones with anilines, 2-aminopyridine and 1,2-phenylenediamine, respectively, in the presence of N-methylimidazolium trifluoromethanesulfonate ionic liquid supported on nano-silica ([Hmim]OTf@nano-SiO2) as a reusable catalyst under solvent-free conditions has been developed. The bis-derivatives of these compounds were also prepared efficiently, for the first time, using this catalytic system. All products were obtained in high yields and in short reaction times.

A new supported phosphonium based ionic liquid, propylphosphonium hydrogen carbonate ionic liquid supported on nano-silica (PPHC–nSiO2), was prepared and characterized by FT-IR, TGA, SEM and ICP techniques. The resulting catalyst was used for the efficient synthesis of fully substituted pyridines via a one-pot multicomponent reaction of aldehydes, malononitrile, and thiols under solvent-free conditions. Expedient synthesis of bis-pyridines from dialdehydes and/or dithiols by using this catalytic system can be considered as a noteworthy advantage of this method. Furthermore, there was no obvious loss of catalytic activity even after 5th cycle.

The Lewis acidic room-temperature ionic liquid, [bmim][InCl 4 ], was found to be an efficient catalyst for the regio­selective synthesis of fully substituted pyrazoles and pyrazole-fused cyclohexanones through condensation of hydrazones with symmetrical and unsymmetrical 1,3-diketones. This procedure is simple, ­affording the corresponding products in good to high yields.

An efficient protocol for the excellent diastereoselective synthesis of pyrazolines via a three-component reaction of aldehydes, hydrazines and dimethyl acetylenedicarboxylate (DMAD) in the presence of a bifunctional Bronsted acidic ionic liquid as a reusable catalyst under solvent-free conditions is reported. Easy work-up, short reaction times, high yields of the products and an environmentally benign procedure avoiding toxic organic solvents are other significant features of this method.

The epoxidation of alkenes with hydrogen peroxide catalyzed by [PZnMo 2 W 9 O 39 ] 5- , ZnPOM, supported on ionic liquid-modified silica, Im-SiO 2 , is reported. The immobilized catalyst, [ZnPOM@Im-SiO 2 ] was characterized by elemental analysis, X-ray diffraction (XRD), scanning electron microscopy (SEM), FT-IR and UV–Vis spectroscopic methods. This new synthesized hybrid catalyst was applied for efficient epoxidation of various olefins with aqueous H 2 O 2 in acetonitrile under reflux conditions. This solid catalyst can be easily recovered by simple filtration and reused several times without significant loss of its catalytic activity.

The efficient synthesis of novel fused pyridines via the three component condensation of aldehydes, kojic acid, and 6-amino-1,3-dimethyluracil, catalyzed by the ionic liquid aminopropyl-1,3,5-triazine-2,4-diphosphonium hydrogen sulfate supported on functionalized nano-silica, under solvent-free conditions is reported. Additionally, bis-derivatives of these compounds were smoothly synthesized from dialdehydes. This method has the advantages of mild conditions, high yields, short reaction times, easy work-up, and being environmentally friendly. Moreover, the catalyst can be easily separated from the reaction mixture, recycled, and reused several times without a noticeable decrease in catalytic activity.

Preparation and characterization of vanadium-containing polyphosphomolybdates supported on ionic liquid-modified MCM-41, MCM-41-Im, are reported. The catalyst, [PVMo@MCM-41-Im], was characterized by elemental analysis, X-ray diffraction, scanning electron microscopy and also FT-IR, and UV-Vis spectroscopic methods. This heterogeneous catalytic system was applied for efficient epoxidation of various olefins in the presence of tert-BuOOH in 1,2-dichloroethane under reflux. The catalyst can be reused several times without apparent loss of its catalytic performance.

Di[1,6-bis(3-methylimidazolium-1-yl)hexane] decatungstate dihydrate ([C6(MIm)2]2W10O32. 2H2O) as a new family of polyoxometalate-based dicationic ionic liquids (POM-DIL) is synthesized and employed as a novel and powerful heterogeneous catalyst in the synthesis of 4-arylidene-2-phenyl-5(4)-oxazolones (azlactones) under ultrasound-assisted solvent-free condition. On the basis of the results, the products were obtained in excellent yields under mild condition. Utilization of easy work-up and purification make it very interesting from an economic perspective. Moreover, a recycling study confirmed that the catalyst can be reused multiple times without significant loss of its activity.

An efficient method for the synthesis of a series of 2,3-disubstituted-2,3-dihydroquinazolin-4(1H)-ones is described via one-pot condensation reaction of isatoic anhydride, aryl aldehydes, and primary amines using a Bronsted acidic ionic liquid, [Hmim][NO3], as a catalyst and medium. The present protocol enjoys convenient reaction and simple work-up, greenness, short reaction times, and reusable catalyst as well as mild reaction conditions. J. Heterocyclic Chem., (2011).

A new and practical promoter system for one-pot, efficient, chemoselective synthesis of 4-arylidene-2-phenyl-5(4H)-oxazolones using [(C14H24N4)2W10O32]-[bmim]NO3 under solvent-free conditions is described. The present work opens up a new and ecofriendly synthetic route to Erlenmeyer–Plochl adducts from primary benzyl alcohols in a one-pot operation.

A simple, green and chemoselective method for methoxymethylation and ethoxymethylation of primary and secondary alcohols using a Lewis acidic room temperature ionic liquid, [C4mim][InCl4], as catalyst and reaction medium under ambient temperature, microwave and ultrasonic irradiations is reported. In this catalytic system, the corresponding MOM-and EOM-ethers are obtained in excellent yields and in short reaction times. Furthermore, this catalytic system was used for mild and efficient transformations of these protected alcohols to their corresponding acetates and trimethylsilyl ethers under thermal conditions and microwave and ultrasonic irradiations.

A novel, clean and efficient tandem process has been established for the synthesis of 2,4,6-triarylpyridines from primary aryl alcohols or 1-arylethanols using 1-methylimidazolium nitrate in 1-butyl-3-methylimidazolium tetrafluoroborate as a binary task-specific ionic liquid under microwave irradiation.

A simple and efficient method for the synthesis of 2,4,5-triaryl-1 H-imidazole derivatives in good to excellentyields by reaction between hexamethyldisilazane and arylaldehydes,benzyl alcohols, benzyl halides in molten tetrabutylammonium bromideas an inexpensive and non toxic solvent has been developed. Theremarkable advantages of this method are the simple workup procedure, highyields of products, the use of an ionic liquid as a green solvent, andthe availability of reagents.

A simple, efficient, facile and eco-friendly process for the synthesis of thioamides from nitriles using 1,6-bis(3- methylimidazolium-1-yl)hexane chloride [C6(mim)2Cl2] as a dicationic ionic liquid (DIL) was developed. The ionic liquid was easily separated from the reaction mixture and was recycled at least four times without any loss of its activity.

1-Methylimidazolium hydrogensulfate, [Hmim][HSO4], a Bronsted acidic room temperature ionic liquid, is used as a catalyst and reaction medium for facile and eco-friendly deprotection of methoxymethyl (MOM) and ethoxymethyl (EOM) ethers to their corresponding alcohols under thermal conditions (Δ) and microwave irradiation (MW). Furthermore, one-pot interconversion to the respective acetates and trimethylsilyl (TMS) ethers was also achieved.

A mild, efficient, facile and eco-friendly procedure for the synthesis of 2,4-diarylthiazoles from arylthioamides and α-bromoacetophenones in 1-n-butyl-3-methylimidazolium tetrafluoroborate as a “green” media under ultrasound irradiation at room temperature is described. It is interesting to mention that only one product was obtained when two different α-bromoacetophenones were reacted with 1,3-phenyl dithioamide as the substrate. Work-up is very simple and there is no need to purify the product. A recycling study confirmed that the ionic liquid can be reused multiple times without a significant loss in its activity.

An efficient and green procedure for the synthesis of 2,4,5-trisubstituted imidazoles with various aldehydes using a catalytic amount of 1-methylimidazolium hydrogenesulfate as an active and low cost Brönsted acidic room temperature ionic liquid has been developed. The ionic liquid was easily separated from the reaction mixture and was recycled five times without any loss in activity.Key words: ionic liquid, 2,4,5-trisubstituted imidazoles, [Hmim]HSO4, aldehyde, benzil.

Alcohols were converted to the corresponding THP, THF or TMS ethers in high to excellent yields in 1-n-butylpyridinium chloroferrate media as a stable and low cost room temperature ionic liquid. In addition, oxidation of these ethers to their aldehydes or ketones without any overoxidation reactions in this ionic liquid was also performed.

A new and efficient method has been developed for the regio- and chemoselective synthesis of β -hydroxysulfides with the ring-opening reaction of 1,2-epoxides by diaryl disulfides and zinc powder in the presence of a catalytic amount of BiCl 3 in molten tetrabutyl phosphonium bromide as an ionic liquid.

The oxidation of benzyl halides to aldehydes with bismuth nitrate pentahydrate in an ionic liquid was studied. Also, an efficient one-pot synthesis of 3,4-dihydropyrimidin-2(1H)-ones from benzyl halides using bismuth nitrate pentahydrate in tetrabutylammonium fluoride (TBAF) as an in situ oxidant and catalyst is described.

A novel and efficient process for the synthesis of 3,5-diaryl-1,2,4-thiadiazoles from aryl nitriles in 1-butyl-3-methylimidazolium bromide promoted by (NH4)2S and TCT–DMSO is described.

Enamination of a wide various primary amines was successfully carried out in the presence of catalytic amounts of cerium chloride heptahydrate in ionic liquid and solvent-free conditions as 'green' media under mild reaction conditions.

A facile and efficient synthesis of β-amino alcohols by ring opening of epoxides with anilines in good to excellent yields in the presence of catalytic amounts of Bi(TFA) 3 or Bi(OTf) 3 via the use of molten tetrabutylammonium bromide (TBAB) as an ionic liquid is described. In addition, the observed chemoselectivity can be considered as a noteworthy advantage of this method.

The synthesis of a variety of 2,3-disubstituted quinolines has been achieved successfully via a one-pot three-component reaction of arylamines, arylaldehydes and aliphatic aldehydes in the presence of butylpyridinium tetrachloroindate(III), [bpy][InCl4], ionic liquid as a green catalyst and solvent. Mild conditions with excellent conversions, and simple product isolation procedure are noteworthy advantages of this method. The recyclability of the ionic liquid makes this protocol environmentally benign.

The Lewis acid room temperature ionic liquid, [bmim][InCl4], was found to be an efficient and green catalyst for the highly chemoselective and one-pot conversion of MOM- or EOM-ethers into their corresponding nitriles, bromides, and iodides under microwave irradiation. The procedures are simple, rapid, and high yielding. The catalyst exhibited a remarkable reactivity and is reusable.

An efficient procedure is elaborated for the synthesis of tetrasubstituted pyrazoles (IV) by cyclization—aromatization of aryl hydrazones (I) with aldehydes (II) and DMAD (III).

The combination of TiCl 3 OTf with 1-butyl-3-methylimidazolium bromide is found to be an efficient and novel catalytic system for chemoselective one-pot transformation of arylaldoximes to their corresponding thioamides in high to excellent yields.

A novel, environmentally benign, fast, and efficient three-component one-pot protocol for the synthesis of the title compounds (IV) is reported by using an ionic liquid as a safe, inexpensive, and reusable catalyst (four times).

A variety of pyrazolo[3,4-d]pyrimidine-6(7H)-thione derivatives were easily synthesized with a novel, simple, efficient, and regioselective method via three-component condensation reaction of 5-methyl-1H-pyrazol-3-amine, arylisothiocyanates, and aldehydes in the presence of catalytic amount of p-toluenesulfonic acid (p-TSA) in 1-butyl-3-methylimidazolium bromide ionic liquid with excellent yields and short reaction times.

Simple and efficient methods for the synthesis of the title compounds (II), by using available and inexpensive reagents, is developed in the ionic liquid Bu4NBr as a green solvent.

The ionic liquid acts both as catalyst and suitable solvent for the microwave-assisted reaction.

4(3 H )-Quinazolinones have been synthesized in high to excellent yields through the one-pot condensation of anthranilic acid, trimethyl orthoformate and primary amines in the presence of 5 mol % of Bi(TFA) 3 immobilized on [nbp]FeCl 4 as a room temperature ionic liquid.

A new and efficient method has been developed for the regio- and chemoselective synthesis of β -hydroxysulfides with the ring-opening reaction of 1,2-epoxides by diaryl disulfides and zinc powder in the presence of a catalytic amount of BiCl 3 in molten tetrabutyl phosphonium bromide as an ionic liquid.

The oxidation of benzyl halides to aldehydes with bismuth nitrate pentahydrate in an ionic liquid was studied. Also, an efficient one-pot synthesis of 3,4-dihydropyrimidin-2(1H)-ones from benzyl halides using bismuth nitrate pentahydrate in tetrabutylammonium fluoride (TBAF) as an in situ oxidant and catalyst is described.

A new, efficient, clean, and regioselective 'one-pot' procedure for thiolyzation of epoxides with aryl disulfides catalyzed by cerium(III) chloride heptahydrate immobilized on tetrabutyl phosphonium bromide as an ionic liquid is reported.

Enamination of a wide various primary amines was successfully carried out in the presence of catalytic amounts of cerium chloride heptahydrate in ionic liquid and solvent-free conditions as 'green' media under mild reaction conditions.

The Lewis acid room temperature ionic liquid, [n-Bu4P][CuBr3], was found to be an efficient and reusable catalyst for three component synthesis of fully substituted pyrazoles from the reaction of aldehydes, arylhydrazines and dimethyl acetylenedicarboxylate (DMAD). This catalytic system is simple and chemoselective with high yields.

A supported ionic liquid bearing sulfonic acid groups was synthesized by anchoring 3-sulfopropyl-1-(3-propyltrimethoxysilane)imidazolium hydrogen sulfate onto nano-silica and characterized by FT-IR spectroscopy, elemental analysis and scanning electron microscopy (SEM) techniques. This catalyst was used for the efficient one-pot multi-component synthesis of indazolophthalazine-triones and bis-indazolophthalazine-triones. Moreover, the catalyst could be reused at least seven times without any significant loss of activity.

A new, efficient, clean, and regioselective 'one-pot' procedure for thiolyzation of epoxides with aryl disulfides catalyzed by cerium(III) chloride heptahydrate immobilized on tetrabutyl phosphonium bromide as an ionic liquid is reported.

An elegant and efficient procedure with exceptionally mild conditions for the regioselective synthesis of pyrazoles by the reaction of various 1,3-diketones and hydrazines/hydrazides using a multi-SO 3H Bronsted acidic room temperature ionic liquid as a powerful catalyst in aqueous media has been developed. The ionic liquid was easily separated from the reaction mixture and was recycled and used for at least six consecutive runs without any loss of activity.

A new, simple and efficient procedure for the one-pot conversion of alcohols instead of aldehydes to the corresponding 3,4-dihydropyrimidin-2(1H)-ones (DHPMs) with Bi(NO 3 ) 3 .5H 2 O as a commercially available, inexpensive, stable and non-toxic reagent in two media, acetonitrile (as an organic solvent) and tetrabutylammonium bromide (as an ionic liquid) is described. This one-pot oxidation-cyclocondensation reaction is performed without isolation of any intermediate (aldehyde) and thus reducing time, saving energy and raw materials. On the other hand treatment of primary alcohols with this new one-pot method produce the dehydropyrimidinones in higher yields than those are obtained in the traditional method.

Diaryl disulfides undergo regioselective ring-opening of 1,2-epoxides in the presence of zinc powder and 3-4 mol-% of bismuth(III) trifluoroacetate or 1 mol-% of bismuth(III) triflate in molten tetrabutylphosphonium bromide (TBPB) to afford the corresponding β -hydroxy thioethers in good to excellent yields.