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A library of pyran-2H-one-3-ylmethylidene and chromene-2H-one-3-ylmethylidene derivatives of the titled heterocyclic framework was synthesized from 3-acyl-4-hydroxypyran/chromene-2H-one via sequential reaction with thiosemicarbazide and dialkyl acetylenedicarboxylates. The syntheses were carried out under efficient catalysis of a new binary ionic liquid mixture [L-prolinium chloride][1-methylimidazolium-3-sulfonate] in one pot and solvent-free conditions. Calculations based on density functional theory displayed that the barrier energy for interconversion of the two possible diastereomeric isomers of each product is less than the thermal energy of molecules at room temperature, as only one product can be resolved from a given reaction mixture. This seems to be the case for the previously reported hydrazonothiazolidines. The binary ionic liquid mixture melts at near room temperature and can be considered as a solution of HCl in 1:1 mixture of two zwitterionic species. It proved to be more efficient than its constituents in catalyzing the above synthesis in one-pot operation. Some of the synthesized products have shown pronounced antibacterial activities. The ionic liquid is virtually stable in air and moisture, as can be retrieved several times without appreciable decrease in its catalytic activity.

Benzylation of DBU followed by anion exchange of the resulting salt with trifluoroacetate gave nearly quantitatively the ionic liquid [Bn-DBU][TFA]. It is shown here to be an efficient catalyst for the synthesis of 1H-pyrazolo[1,2-b]phthalazine-5,10-diones via the three-component reaction of phthalhydrazide, aromatic aldehydes, and active α-methylene nitriles. DFT calculations at the B3LYP/SVP level and the experimental results are in agreement with a three-step mechanism for this reaction. Based on the DFT calculations, the catalytic effect largely arises from the intrinsic ionic properties of the ionic liquid rather than its action as a simple base. These calculations also predict the existence of two close-in-energy activated complexes whose rate determining roles and energies depend on their interaction with the anionic component of the ionic liquid, as [Bn-DBU][TFA] has shown a higher catalytic activity than [Bn-DBU][OAc]. This mechanistic approach opens up new and promising insights into the rational design of ionic liquid catalysts for the synthesis of 1H-pyrazolo[1,2-b]phthalazine-5,10-diones. The synthetic method presented here has several prominent advantages. [ABSTRACT FROM AUTHOR]

A nearly neutral but protic chiral ionic liquid was prepared via neutralization of (1 S)‐(+)‐camphor‐10‐sulfonic acid with N,N‐dimethyl‐n‐octylamine. The structure of this room temperature ionic liquid was confirmed by NMR spectroscopy. It was proved to be an efficient mild promoter for the synthesis of some novel spiro‐oxindoles. The ionic liquid has shown a high asymmetric induction potential, as the spiro‐oxindoles were obtained in high optical purities. All the synthesized spiro‐compounds are new. [ABSTRACT FROM AUTHOR]

An active imidazolium-based ionic liquid mixture was developed for efficient synthesis of some novel 4,6-diaryl-3-(chlorosulfonyl)-1,2-oxathiine-2,2-dioxides (chlorosulfonyl-δ-sultones) from simple acetophenones at room temperature. The ionic liquid mixture acts as a catalyst to condense two molecules of an acetophenone derivative and as a mild sulfonating agent to convert the resulting condensate into 4,6-diaryl-1,2-oxathiine-2,2-dioxides, and finally as a chlorosulfonating reagent to deliver the desired fully unsaturated chlorosulfonyl-δ-sultones in onepot. The products were separated easily from the reaction mixture and showed valuable fluorescence properties. The structures of these products are in good agreement with their 1 H NMR, 13 C NMR, and mass spectral data. All rights reserved. [ABSTRACT FROM AUTHOR]

An acidic liquid 1,3-ionene was synthesized from co-oligomerization of epichlorohydrin and imidazole followed by subjecting the resulting light oligomer to anion exchange with concentrated sulfuric acid and subsequent sulfonylation with chlorosulfonic acid. The 1 H and 13 C NMR spectra of the synthesized oligo(ionic liquid) displayed significant chemical shifts on transferring the oligomer from D 2 O to DMSO. This observation was interpreted as resulting from a conformational change in the multicationic oligomer. Application of this oligo(ionic liquid) as both solvent and acidic promoter to the synthesis of pyrano[3,2- c ]quinolines and pyrano[2,3- d ]pyrimidines gave fairly high yields of the products in short reaction times. The oligo(ionic liquid) is virtually stable, as could be stored for several months at room temperature and can be easily recycled several times in the synthesis of pyrano[3,2- c ]quinolines and pyrano[2,3- d ]pyrimidines at 80 °C without appreciable loss of activity. [ABSTRACT FROM AUTHOR]

Novel pyrazole-fused spiro[4H-pyridine-oxindoles] were synthesized under the catalysis of the binary ionic liquid mixture [1,1,3,3-tetramethylguanidinium chloride][1-methylimidazolium-3-sulfonate] in solvent-free conditions. The hitherto unreported binary ionic liquid (BIL) was synthesized via an acid–base reaction and has a melting point much lower than that of the moderate temperature ionic liquid, [1,1,3,3-tetramethylguanidinium chloride], it is made from. The synthesis of the spiro-products was realized via a thermodynamically-favored three-component domino reaction between isatins, 1-phenyl-1H-pyrazol-5(4H)-ones, and 4-aminocoumarin. The domino reaction was highly convergent and functional group tolerant, providing a rapid route to synthesize spiro[4H-pyridine-oxindoles] in fairly high yields from simple bench-stable starting materials. No by-products could be resolved from the reaction mixtures under the optimized conditions. [ABSTRACT FROM AUTHOR]

Addition of chlorosulfonic acid to N -methyl-2-pyrrolidone (NMP) resulted in the formation of a low-melting solid with the advantages of being reasonably stable for at least 4 months at ambient temperature and easy to handle. This solid forms homogeneous solutions with acetophenone derivatives, which on heating in the absence of any additional solvent and catalyst lead to production of the desired 1,3-dienic δ-sultones in fairly high yields and short reaction times. Beside its role as a solvent, the NMP-ClSO 3 H salt efficiently catalyzes the self-condensation of acetophenones and plays as a mild sulfonating agent in conversion of the resulting condensates into δ-sultones. The reaction protocol is simple and follows a green work-up procedure that enables to recover the reaction residues and prevent the emission of wastes into the environment. [ABSTRACT FROM AUTHOR]

A class of sulfonic ionic liquids, with the supremacy of methylsulfonylimidazolium triflate hydrochloride, was found to be efficient for catalyzing the self-condensation of acetophenone derivatives and sulfonating the resulting condensates in a one-pot rapid reaction leading to the synthesis of 4,6-diaryl-1,2-oxathiine-2,2- dioxides (diaryl-δ-sultones). [ABSTRACT FROM AUTHOR]

The ionic liquid [BMIm]BF4 doped with LiBF4 was found to efficiently catalyze the three-component reaction between isocyanides, acetylenic esters and enols or phenols at room temperature, leading to rapid synthesis of 2-aminopyran-annulated systems in fairly high yields. Efficiency of this catalysis and its benefits in terms of improved yields and reaction times could be ascribed to involvement of relatively stable organolithium intermediates which make the reaction more feasible. The ionic solution tolerates a significant amount of dissolved LiBF4, while remaining fluid at room temperature to serve as solvent for the organic substrates. It retains its initial integrity after use and recovery, as it could be recycled several times without appreciable catalytic decrements. The catalytic activity of the ionic composite is completely lost in the absence of LiBF4. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Abstract: The synthesis of novel 4-substituted-3,4-dihydro-6H-pyrano[3,2-c]quinoline-2,5-diones was accomplished efficiently via a three-component reaction between 4-hydroxyquinoline-2-one, Meldrum’s acid, and an alkyl or arylaldehyde under catalysis by [Bmim]HSO4. The ionic liquid catalyst offers the advantage of realizing the synthesis of the title products at ambient temperature and widens the scope of the reactants to include aliphatic aldehydes with respect to the catalysts already applied for similar syntheses. [Copyright &y& Elsevier]

Abstract: A homogeneous ionic liquid made up of 0.5mol% Mg(BF4)2 doped in [BMIm]BF4 was obtained from a mixture of MgCl2 and [BMIm]Cl subjected to anion exchange with NaBF4. The ionic liquid efficiently catalyzes the synthesis of 1,8-dioxo-octahydroxanthenes, 14-aryl-14H-dibenzo[a,j]xanthenes, and 1,8-dioxo-decahydroacridines, giving excellent yields in short periods of time at 80°C. The integrity of the ionic liquid remains reasonably unchanged when it is separated from the reaction mixture by water extraction, as it can be recycled several times without any loss of activity in each of the title syntheses. Magnesium cation, though in low concentration, appeared as an essential element of this ionic liquid catalysis, perhaps due to its non-coordinated existence giving rise to a promoted Lewis acidic characteristic. Application of this new homogeneous catalyst system offered the advantages of high yields, short reaction times, and easy workup procedure compared to the conventional methods of the syntheses. [Copyright &y& Elsevier]

Abstract: The mildly basic ionic liquid N,N,N,N-tetramethylguanidinium triflate (TMGTf) was found to be a very effective solvent for the reaction between 4-hydroxy-6-methyl-2H-pyran-2-one, Meldrum''s acid, and aldehydes to afford some novel pyrano[4,3-b]pyran-2,5-diones in high yields at room temperature. The stages, through which these reactions might proceed, depend largely on the nature of the aldehyde substrates. The reaction of aliphatic aldehydes has given access to some novel carboxylated products. [Copyright &y& Elsevier]

Abstract: A simple and efficient one-pot approach for assembling some fused spiro[4H-pyran-oxindole] heterocycles by means of three-component reactions between isatins, malononitrile or ethyl cyano-acetate, and 1,3-dicarbonyl compounds is reported. The combinatorial syntheses were achieved for the first time without applying extra activation energy at ambient temperature while making use of [BMIm]BF4 as an ionic liquid catalyst. Good functional group tolerance and broad scope of usable substrates are other prominent features of the present methodology. [Copyright &y& Elsevier]

Abstract: Three ionic liquids, [BMIM][BF4] doped with 60mol% of LiCl ([BMIM][BF4]–LiCl), N,N,N,N-tetramethylguanidinium trifluoroacetate (TMGT), and N,N,N,N-tetramethylguanidinium triflate (TMGTf) were found useful as catalyst solvents for controlled 3-indolylation of isatins. Our investigation revealed that the reaction between isatin and indoles in [BMIM][BF4]–LiCl or TMGTf media stops at the step of addition of the two components providing 3-indolyl-3-hydroxyindolin-2-ones while the ionic liquid TMGT runs the reaction further through accompanying Friedel–Crafts substitution to afford symmetrical 3,3-di(indol-3-yl)indolin-2-ones. To take advantage of the difference between the effects of these ionic liquids on the reaction progress, we planned a two-step protocol for the efficient synthesis of unsymmetrical 3,3-di(indol-3-yl)indolin-2-ones. [Copyright &y& Elsevier]

Abstract: Two ionic liquids, N,N,N,N-tetramethylguanidinium trifluoroacetate (TMGT) and the unprecedented N,N,N,N-tetramethylguanidinium triflate (TMGTf), were used as catalyst solvents in condensations between indoles and arylaldehydes or 1,3-diketones providing a simple and efficient method for synthesis of bis(3-indolyl)methanes or casually 3-alkenylindoles due to stereoelectronic concerns of reactants. The ionic liquids are easily separated and reused for several times. [Copyright &y& Elsevier]

The reaction of triethyl(sulfonyl)ammonium chlorosulfonate with 1,1,3,3-tetramethylguanidine (TMG) gave a low-melting complex salt with amphipathic and acidic characters. The salt has a great tendency towards solvation of organic substrates upon slight heating, so it was employed as a homogeneous acidic and functional ionic liquid catalyst in the expedient synthesis of benzo b pyrans, pyrano[4,3- b pyrans, pyrano[3,2- c quinolones, and pyrido[2,3- d pyrimidines. The catalytic activity of the complex salt is much better than the simple salts composing it. Spectroscopic studies and chemical analysis of the salt revealed that its empirical formula is in agreement with neutralization of TMG by two H 2 SO 4 molecules. The HSO 4 − anions of the salt seem to form extensive H-bonding with the constituting ammonium cations and Cl−, resulting in melting point depression of the complex salt due to the melting points of pure triethylamine and TMG hydrochloride salts. Another significant feature of this solid salt is that it can preserve its composition even after several times of separation from aqueous extracts and can be handled easily without danger. Unlabelled Image • A novel complex salt with mp of 118 °C and amphipathic character was prepared. • The salt is a solid solution of HCl trapped in a network of H-bonded ions. • The salt do not change chemical composition on successive melting and wetting. • It is a powerful amphipathic solvent, so can fuse with org substrates at <100 °C. • It was successfully tested as an acid catalyst in some representative syntheses. [ABSTRACT FROM AUTHOR]

Chemical formulas explaining the synthesis of pyran-annulated heterocycles using an ionic-liquid metal composite and homogeneous catalyst are presented.

The use of [bmim]HSO4 renders possible the preparation of the title compounds at ambient temperature via three component reaction between hydroxyquinolinone (I), Meldrum′s acid, and aldehydes. [ABSTRACT FROM AUTHOR]

Abstract: An unexpected condensation profile was observed for the three-component reaction of 5,5-dimethyl-1,3-cyclohexadione (dimedone), various anilines, and isatin leading to the synthesis of novel 2-arylpyrrolo[2,3,4-kl]acridin-1(2H)-ones in the ionic liquid [HMIm]HSO4. Regeneration of the enamine group after the initial condensation reaction associated with participation of the restored amine group in translactonization with the pyrrolidone ring are suggested as the main differentiating events being favored over addition of the second dimedone molecule, with respect to similar reported reactions. [Copyright &y& Elsevier]

• DBU based dicationic and monocationic ionic liquids were synthesized and characterized. • Thermal stability of DBU based ionic liquids was determined. • Structural properties of DBU based ionic liquids were studied. • Interaction energy in DBU based ionic liquids was explored. In this study, the new dication ionic liquids (DILs) based on para-xylyl linked bis-1,8-diazobicyclo [5.4.0] undec-7-ene ([p-C 6 H 4 (CH 2 DBU) 2 ]2+) dication and their corresponding monocation ionic liquids (MILs) containing the bis(trifluoromethanesulfonyl) imide [NTf 2 ]− and trifluoromethanesulfonate [OTF]− anions are synthesized. The method is based on the functionalization reaction of DBU salts using a simple procedure under microwave irradiation, followed by anion exchange. The obtained ILs are characterized by 1H-NMR, 13C-NMR, and FT-IR spectroscopy. The thermal decomposition of [p-C 6 H 4 (CH 2 DBU) 2 ][NTf 2 ] 2 , [p-C 6 H 4 (CH 2 DBU) 2 ][OTF] 2 , [C 6 H 5 −CH 2 DBU][NTf 2 ] and [C 6 H 5 −CH 2 DBU][OTF] ILs are measured using thermogravimetric (TGA) analyses and differential scanning calorimetry (DSC) in the temperature range from 25 to 800 °C. The thermal behavior confirmed that the DILs and MILs including [NTf 2 ]− are more stable than the DILs and MILs including [OTF]− that is in good agreement with the greater dispersion energy calculated for [NTf 2 ]− based ILs. The [p-C 6 H 4 (CH 2 DBU) 2 ][NTf 2 ] 2 DIL shows good thermal stability up to 435°C which makes them suitable for thermal application. Finally, the cation-anion interactions were investigated in both DILs and MILs using DFT-M06-2X functional in conjunction with the 6-311++G(d,p) basis set. The results indicate that hydrogen bonding is stronger in the IL containing [OTF]− anion. The calculations in the solution phase with COSMO-RS method show that the ILs including [OTF]− anion have greater solvation energy and for the DILs are larger than those of MILs. [ABSTRACT FROM AUTHOR]

The experimental approaches coupled with computational methods are powerful tools to understand the physicochemical properties of ionic liquids. The 1,8-diazobicyclo[5.4.0]undec-7-ene-8-benzylium ([Bn-DBU]+) cation is a N-substituted DBU cation that was joined with various anions for production of [Bn-DBU][Y 1-8 , (Y 1-8 = CH 3 CO 2 −, PhSO 2 −, PhSO 3 −, HCO 3 −, HSO 4 −, CF 3 CO 2 −, BF 4 −, and SCN−) ionic liquids (ILs). In this study, at first, several aprotic ionic liquids composed of [Bn-DBU]+ cation and various anions were synthesized and characterized experimentally by the combined of 1HNMR and FTIR spectroscopies, and thermogravimetric analysis (TGA). Then, density functional theory (DFT) at M06–2X/6–311++G(d,p) level of theory was used for calculation of the molecular electrostatic potential (MESP), interaction energies, structural parameters, vibrational frequencies, topological properties, charge transfer (CT) values and non-covalent interaction index. • Bn-DBU based ionic liquids were synthesized and characterized. • Thermal stability of Bn-DBU based ionic liquids was determined. • Structural properties of Bn-DBU based ionic liquids were studied. • Interaction energy in Bn-DBU based ionic liquids was explored. • The interionic interactions were characterized. [ABSTRACT FROM AUTHOR]