Ionic Liquid–Mediated Knoevenagel Condensation of Meldrum's Acid and Aldehydes

A simple, efficient, and green protocol for Knoevenagel condensation of Meldrum's acid and aldehydes in ionic liquid at room temperature without any catalyst is described. The reaction has been performed in different ionic liquids. The enhancement in the rate is observed in Brönsted acidic ionic liquid 1‐methylimidazolium trifluoroacetate [Hmim]Tfa, which furnishes quantitative yields with 4–30 min in most of the cases. Furthermore, ionic liquid is easily reused without any appreciable loss in activity.     

Dicyano-Functionalized MCM-41-Supported Palladium Complex as An Efficient Catalyst for Allylation of Aldehydes and Ketones

Dicyano-functionalized MCM-41-supported palladium complex was prepared from dicyano-functionalized MCM-41 and palladium chloride. This complex exhibited high catalytic activity in the allylation of aldehydes and ketones with allylic chlorides in the presence of SnCl2. This polymeric palladium complex can be recovered and reused without noticeable loss of activity.     

Envirocat Epzg® as an Efficient Heterogenous Catalyst for Thioacetalization of Carbonyl Compounds

The reaction of carbonyl compounds with 1,2-ethanedithiol was efficiently catalyzed by Envirocat EPZG® to afford the corresponding dithioacetals in excellent yields.     

Brønsted Acid Ionic Liquid [(CH2)4SO3HMIM][HSO4] as Novel Catalyst for One-Pot Synthesis of Hantzsch Polyhydroquinoline Derivatives

1-(4-Sulfonic acid)butyl-3-methylimidazolium hydrogen sulfate ([(CH₂)₄SO₃HMIM][HSO₄]) efficiently catalyzed a four-component Hantzsch reaction of aldehyde, ethylacetoacetate, dimedone, and ammonium acetate to afford the corresponding polyhydroquinoline derivatives.     

Ambient Ionic Liquids Used in the Reduction of Aldehydes and Ketones

The sodium borohydride reduction of aldehydes and ketones to corresponding alcohols has been accomplished via the use of ionic liquids. The alcohols are easily obtained with excellent yields and the ionic liquid BMImBF4 could be reused.     

A Modified and Green Procedure for the Synthesis of β-Amido Ketones Using a BrΦnsted-Acidic Ionic Liquid as Novel and Reusable Catalyst

A green and improved method for the synthesis of β‐amido ketones through one‐pot multi‐component reaction of an enolizable ketone, aryl aldehyde, acetonitrile or benzonitrile in the presence of trimethylsilyl chloride using 3‐methyl‐1‐(4‐sulfonic acid)butylimidazolium hydrogen sulfate [(CH₂)₄SO₃HMIM][HSO₄], a Br?nsted‐acidic ionic liquid, as an effective and recyclable catalyst is described. The present methodology offers several advantages such as simple procedure with an easy work‐up, relatively short reaction time, and good to excellent yields.     

New Approach for the Synthesis of N‐Indolyl Ketones and Aldehydes

A new approach for the synthesis of N‐indolyl ketones and aldehydes was developed. In the reaction of N‐indolyl carboxylic acids with alkyl lithium, an interesting phenomenon appeared when using THF as solvent instead of ethyl ether.     

Heteropoly Acids as Heterogeneous and Reusable Catalyst for α-Thiocyanation of Ketones

Simple, efficient, and mild method for α-thiocyanation of ketones in presence of heteropolyacid has been developed. This methodology offered α-oxothiocyanates in good to excellent yields at room temperature in a highly selective manner. The catalyst could be efficiently recovered from the reaction and reused.     

[BPy]HSO4 Acidic Ionic Liquid as a Novel,Efficient, and Environmentally Benign Catalyst for Synthesis of 1,5‐Benzodiazepines under Mild Conditions

A novel and simple ionic liquid methodology for the synthesis of 1,5‐benzodiazepines is described. 1‐Butylpyridinium hydrogen sulphate ([BPy]HSO₄), an acidic room‐temperature ionic liquid, as a novel and efficient catalyst, was synthesized and used in the preparation of a series of 1,5‐benzodiazepine derivatives by the reaction of o‐phenylenediamine with chalcones under mild conditions. This method is easy, efficient, environmentally friendly, economical, free of toxic catalysts, and has good yields for the formation of 1,5‐benzodiazepines     

Reduction of Aldehydes and Ketones with Potassium Borohydride as Reductant

A series of aldehydes and ketones were reduced by potassium borohydride in an ionic liquid/water ([bmim]PF6/H2O) biphasic system to afford corresponding alcohol with high purity in excellent yields. The ionic liquid/water biphasic system could promote the chemoselectivity and the substituents such as nitro group and chlorine remained intact. Aromatic ketones were not as active as aromatic aldhydes and cyclic ketones owing to their higher steric hindrance. The ionic liquid could be recycled and reused. This protocol has notable advantages of no need of phase transfer catalyst and organic solvents, mild conditions, simple operation, short reaction time, ease work-up, high yields and recycling of the ionic liquid.     

Ionic Liquid as Catalyst and Reaction Medium: A Simple and Efficient Procedure for Paal–Knorr Furan Synthesis

The ionic liquid 1-butyl-3-methyl-imidazolium hydrogen sulfate, [bmim]HSO₄, efficiently catalyzes Paal–Knorr furan synthesis without any organic solvent. A wide range of aliphatic and aromatic 1,4-diketones easily undergo condensations to form furan derivatives, providing a general and convenient procedure. The Paal–Knorr reaction of ester-substituted 1,4-diketones is first reported. The ionic liquid can be recovered and reused for subsequent runs without any appreciable loss of efficiency.     

Preparation and Characterization of a Novel Benzimidazolium Bronsted Acid Ionic Liquid and Its Application in the Synthesis of Arylic Esters

A novel Brφnsted acid task specific ionic liquid 1-ethylbenzimidazolium tetrafluoroborate （[Hebim]BF4） with functional benzimidazolium cation was synthesized and characterized by ^1H NMR, IR, MS spectra and elemental analysis. This novel ionic liquid was successfully used as dual solvent-catalyst for the synthesis of arylic esters. Higher yields were obtained in the presence of [Hebim]BF4 in comparison with other imidazolium ionic liquids because of the good solubility of the aromatic alcohols and aromatic carboxylic acids in [Hebim]BF4. The product could be separated conveniently from the reaction system, and the ionic liquid could be easily reused after removal of water under vacuum. After 10 times reuse, the selectivity of the ester was still 100%.     

Organic Reactions in Ionic Liquids: Ionic Liquid Ethylammonium Nitrate–Promoted Knoevenagel Condensation of Meldrum's Acid With Aromatic Aldehydes

The Knoevenagel condensation of Meldrum's acid with aromatic aldehydes proceeded efficiently in a reusable ionic liquid, ethylammonium nitrate, at room temperature in the absence of any catalyst with high yields.     

Perchloric Acid–Doped Polyaniline as an Efficient and Reusable Catalyst for the Synthesis of 2-Substituted Benzothiazoles

2-Substituted benzothiazoles have been efficiently synthesized in good yields by the condensation reaction of o-aminothiophenol with aldehydes in the presence of a catalytic amount of perchloric acid–doped polyaniline (HClO₄/PANI). The low cost, simple recovery, and efficient reusability are remarkable characteristics of this catalyst.     

Brønsted Acidic Ionic Liquid as an Efficient and Reusable Catalyst for One-Pot,Three-Component Synthesis of Pyrimidinone Derivatives via Biginelli-Type Reaction Under Solvent-Free Conditions

A mild and efficient method has been developed for the preparation of pyrimidinone derivatives from the reaction of aromatic aldehydes with cyclopentanone and urea or thiourea in the presence of N-(4-sulfonic acid) butyl triethyl ammonium hydrogen sulfate ([TEBSA][HSO₄]) as the Brønsted acidic ionic liquid and effective catalyst under thermal and solvent-free conditions. Good yields, short reaction times, straightforward workup, reusability of the catalyst, and green conditions are the most obvious advantages of this procedure.

Sulfamic Acid as a Cost-effective Catalyst for Acetolysis of Cyclic Ethers

Sulfamic acid has been used as an efficient catalyst and green alternative for conventional acidic materials to promote the acetolysis reaction of THF to produce 1,4-diacetoxybutane. This method is also applicable in the acetolysis of other cyclic ethers, such as methyl substituted THF and tetrahydropyran and 1,4-dioxane which is less reactivity.     

Guanidinium Lactate Ionic Liquid： An Efficient and Recycling Catalyst for Michael Addition Reaction

A facile and efficient 1, 4-conjungate addition(Michael addition) reaction of active methylene compounds to α,β-unsaturated compounds, catalyzed by guanidinium lactate ionic liquid(IL9), has been developed. A range of chalcones and nitroalkenes together with active methylene compounds have been converted smoothly to the corresponding products in high yields.     

Thiazolium Salt Immobilized on Ionic Liquid: An Efficient Catalyst and Solvent for Preparation of α-Hydroxyketones

Aldehydes were efficiently converted to acyloins and benzoins using a new ionic liquid, 3-[2-(1-butyl-1H-imidazol-1,3-ium-3-yl)ethyl]-4,5-dimethyl-1,3-thiazol-3-ium dibromide 1 . This ionic liquid is introduced as a catalyst and a solvent. Acyloins and benzoins were easily isolated from the reaction mixture via simple extraction, and the ionic liquid could be recycled for further use. Also, α-hydroxy ketones with an aromatic and aliphatic substituent were prepared starting from aromatic and aliphatic aldehydes in the presence of ionic liquid 1 .     

Phosphotungstic Acid Nanoclusters Grafted onto High Surface Area Hydrous Zirconia as Efficient Heterogeneous Catalyst for Synthesis of Octahydroquinazolinones and β-Acetamido Ketones

Phostungstic acid (PWA) nanoclusters grafted onto high surface area polycrystalline hydrous zirconia powder (PWA/ZrO₂) was prepared by wet impregnation method. The zirconia particles were synthesized using a modified sol–gel route. The obtained material was characterized by X-ray diffraction (XRD), UV–Vis–diffuse reflectance spectroscopy (UV–Vis–NIR–DRS), infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and sorptometric techniques. XRD study revealed the presence of tetragonal phase of zirconia in the synthesized sample. TEM study indicates presence of small PWA clusters with size in the range of 5–15 nm well dispersed on the surface of the ZrO₂ particles. The characteristic UV and IR absorption feature of the PWA was retained in the PWA/ZrO₂ material. The PWA/ZrO₂ material was used as an efficient catalyst for the preparation of octahydroquinazolinones and β-acetamido ketones. The octahydroquinazolinones were synthesized by the multicomponent condensation of dimedones, urea and aryl aldehydes in ethanol. Similarly, β-acetamido ketones were synthesized with high yield and purity by four component condensation of aryl aldehydes, enolizable ketones, and acetyl chlorides in acetonitrile. The protocols developed in this investigation using the PWA/ZrO₂ catalyst is advantageous in terms of simple experimentation, high yield and purity of the products and recovery and reutilization of the heterogeneous catalyst.