Solvent‐free Chemoselective Synthesis of 1,1‐diacetates Catalyzed by Iron Zirconium Phosphate

In the present study, a mild, rapid, and efficient method for the protection of aldehydes with acetic anhydride (AA) in the presence of iron zirconium phosphate (ZPFe), at room temperature is reported. Selective conversion of aldehydes was observed in the presence of ketones. Under these conditions, different aldehydes bearing electron‐withdrawing and electron‐donating substituents were reacted with AA and the corresponding 1,1‐diacetates (acylals) were obtained in high to excellent yields. The steric and electronic properties of the different substrates had a significant influence on the reaction conditions. Also, the deprotection of 1,1‐diacetates has been achieved using this catalyst in water. The catalyst was characterized by several physico‐chemical techniques. It was recovered easily from the reaction mixture, regenerated, and reused at least 7 times without significant loss in catalytic activity. This protocol has the advantages of easy availability, stability, reusability of the eco‐friendly catalyst, chemoselectivity, simple experimental and work‐up procedure, solvent‐free conditions and only a stoichiometric amount of AA is needed.     

Al(HSO4)3 as an Efficient Catalyst for the Acetylation of Alcohols in Solution and Under Solvent Free Conditions

Summary. Alcohols are acetylated in a mild, clean, and efficient reaction with acetic anhydride in the presence of a catalytic amount of Al(HSO₄)₃ in solution and under solvent free conditions. All reactions were performed at room temperature in good to high yields.     

Brönsted Acidic Ionic Liquid as an Efficient Catalyst for Acetylation of Alcohols and Phenols

A novel Brönsted acidic room temperature ionic liquid (1‐H‐3‐methyl‐imidazolium bisulfate) is found to catalyze efficiently the acetylation of a wide rang of alcohols as well as phenols with acetic anhydride in good to excellent yields at 50°C under solvent‐free conditions. Products are easily isolated by extraction with ether and the protocol is mild and green, compared to the existing method based on toxic solvents.     

Vanadyl Sulfate (VOSO4.3H2O). An Efficient Catalyst for Acylation of Alcohols and Phenols under Solvent Free Condition

Alcohols and phenols were efficiently acylated with acetic anhydride in the presence of vanadyl sulfate (VOSO₄.3H₂O) at room temperature in high yields.     

Solvent‐Free Preparation of 1,1‐Diacetates from Aldehydes Mediated by Zirconium Hydrogen Sulfate at Room Temperature

A mild and efficient method has been developed for the preparation of acylals in good yields through a reaction of aldehydes with acetic anhydride using Zr(HSO₄)₄ as catalyst at room temperature and under solvent‐free conditions.     

N‐Bromosuccinimide (NBS): A Mild and Efficient Catalyst for Tetrahydropyranylation of Alcohols and Phenols under Solvent‐Free Conditions

Different types of alcohols and phenols are tetrahydropyranylated in the presence of NBS catalyst in good to excellent yields under mild, neutral and solvent‐free conditions.     

Efficient Acetylation of Alcohols,Phenols, and Amines Catalyzed by Melamine Trisulfonic Acid (MTSA)

Melamine trisulfonic acid (MTSA) was easily prepared by the reaction of melamine with neat chlorosulfonic acid at room temperature. This reagent can be used as an efficient catalyst for the acetylation of alcohols, phenols, and amines with Ac₂O under mild and completely heterogeneous reaction conditions.     

Efficient Acetylation of Alcohols and Phenols Catalyzed by Recyclable Lithium Bis(perfluoroalkylsulfonyl)imide

An efficient acetylation of alcohols and phenols catalyzed by lithium bis(perfluoroalkylsulfonyl)-imide was developed. This acetylation features good yields, mild reaction condtions, and simple workup procedures. Furthermore, the catalyst bearing a long perfluoroalkyl chain is recoverable and readily reusable without losing any activity.     

An Efficient Selective Oxidation of Alcohols with Zinc Zirconium Phosphate under Solvent‐free Conditions

Zinc zirconium phosphate (ZPZn) nanoparticles have been used as an efficient catalyst for the selective oxidation of a wide range of alcohols to their corresponding ketones or aldehydes using H₂O₂ as an oxidizing agent without any organic solvent, phase transfer catalyst, or additive. The steric factors associated with the substrates had a significant influence on the reaction conditions. The results showed that this method can be applied for chemoselective oxidation of benzyl alcohols in the presence of aliphatic alcohols. The catalyst used in the current study was characterized by ICP‐OES, XRD, N₂ adsorption‐desorption, NH₃‐TPD, Py‐FTIR, SEM, and TEM. These analyses revealed that the interlayer distance in the catalyst increased from 7.5 to 8.7 Å when Zn²⁺ was intercalated between the layers, whereas the crystallinity of the material was reduced. This nanocatalyst could also be recovered and reused at least seven times without any discernible decrease in its catalytic activity. This new method for the oxidation of alcohols has several key advantages, including mild and environmentally friendly reaction conditions, excellent yields and a facile work‐up.     

Carbon-Based Solid Acid as An Efficient and Reusable Catalyst for One-Pot Synthesis of Tetrasubstituted Imidazoles under Solvent-Free Conditions

Carbon‐based solid acid catalyst was found to be highly efficient, eco‐friendly and recyclable heterogeneous catalyst for the multicomponent reaction of benzil, aromatic aldehyde, primary amine and ammonium acetate, giving rise to 1,2,4,5‐tetrasubstituted imidazoles in good to excellent yields. The present methodology offers several advantages, such as high yields, short reaction time, mild reaction condition and a recyclable catalyst with a very easy work up.     

Chloroferrate(III) Ionic Liquid as Recyclable Catalyst for the Acetylation of Alcohols and Phenols and for 1,1‐Diacylation of Aldehydes

A Lewis acidic ionic liquid, [bmim][FeCl₄], was employed to catalyze acetylation of alcohols and phenols, and the conversion of aldehydes to corresponding 1,1‐diacetates without conventional organic solvents. The catalyst is easily available, water‐tolerant, recoverable and easy to handle.     

Phosphomolybdic Acid: An Efficient and Recyclable Solid Acid Catalyst for the Synthesis of 4,4′-(Arylmethylene)bis(1H-pyrazol-5-ols)

An efficient and environmentally friendly method has been developed for synthesis of 4,4′-(arylmethylene)bis(1H-pyrazol-5-ols) by condensation reaction of aromatic aldehydes with 3-methyl-l-phenyl-5-pyrazolone in the presence of phosphomolybdic acid as a recyclable catalyst in ethanol at ambient temperature in excellent yields.     

An Eco‐friendly Three Component Manifold for the Synthesis of α‐Aminophosphonates under Catalyst and Solvent‐free Conditions,X‐ray Characterization and Their Evaluation as Anticancer Agents

A series of α‐aminophosphonates were synthesized through one‐pot condensation of aryl aldehydes, aryl amines and diethyl phosphite in the absence of any catalyst and organic solvents. All the synthesized α‐aminophosphonates were characterized by spectral and elemental analysis and in the case of compound 4j by X‐ray crystallography. Some of these new α‐aminophosphonate derivatives were found to have cytotoxic activity on the cancer cell line DU145 in vitro by the MTT method.     

Synthesis of Pyrimidinone and 5‐unsubstituted 4, 6‐diarylpyrimidine‐2(1H)‐ones by Using Nano Magnetic Catalyst under Solvent Free Condition

Nano magnetic‐supported sulfonic acid is found to be a powerful and reusable heterogeneous catalyst for the efficient synthesis of pyrimidinones. In this study we use various ketones such as acetophenone and cyclopentanone instead of β‐keto ester in one‐pot synthesis of pyrimidinone at biginelli like reaction. Our objective is to improve conditions for the synthesis of multicomponent reactions using nano magnetic catalyst under solvent free condition. A number of excellent and significant results have been developed that lead our perspective understanding the effect of the magnetic nanoparticles when they are used as catalysts.     

Eco‐friendly and Efficient Synthesis of 2,3‐Dihydroquinazolin‐4(1H)‐ones

A simple and facile method for the synthesis of 2,3‐dihydroquinazolin‐4(1H)‐ones through the direct cyclocondensation of one‐pot three‐component cyclocondensation of isatoic anhydride, ammonium acetate (or primary amines) and aldehydes; and anthranilamide and aldehydes using silica supported ferric chloride (SiO₂‐FeCl₃) as catalyst under solvent‐free conditions is described.     

Fe3+‐Montmorillonite: An Efficient Solid Catalyst for One‐Pot Synthesis of Decahydroacridine Derivatives

Fe³⁺‐montmorillonite was used as a solid acidic catalyst for the synthesis of decahydroacridine derivatives through the condensation of aromatic aldehydes, dimedone and aniline in ethanol. The influence of reaction time, reaction temperature, and the amount of catalyst were studied. All the compounds were characterized by IR, Mp, ¹H NMR and ¹³C NMR analysis.     

Catalytic Synthesis of Chalcones and Pyrazolines Using Nanorod Vanadatesulfuric Acid: An Efficient and Reusable Catalyst

Nanorod vanadatesulfuric acid (VSA NRs ), as a recyclable and ecologically benign catalyst, was used for the one‐pot synthesis of chalcones and 1,3,5‐triaryl‐2‐pyrazolines (TAPs ). Chalcones were prepared via the condensation of substituted acetophenones with aryl‐aldehydes under solvent‐free conditions. Subsequently, the synthesized chalcones were used for the catalytic synthesis of TAPs via two‐component condensation with phenyl hydrazine in refluxing ethanol. VSA is easily prepared by a simple reaction of chlorosulfonic acid and sodium metavanadate of high purity. Compared to conventional procedures, the present protocol offers several advantages such as simplicity of the procedure, appropriate reaction times, high to excellent yields, easily work‐up, recoverability, and reusability of the catalyst, and simple purification of the products.     

A Highly Efficient and Recyclable Solid Acid Catalyst for Synthesis of Spiro-oxindole Dihydroquinazolinones Under Ultrasound Irradiation

A simple,efficient and green procedure for the synthesis of spiro-oxindole dihyfroquinazolinones was developed by multi-component condensation of isatoic anhydride,aniline and isatin in the presence of a novel solid acid catalyst under ultrasound irradiation.The present environmentally benign protocol offers several advantages, such as shorter reaction time,a wide range of fimctional group tolerance,the use of an inexpensive heterogeneous catalyst,and a high yield of products via a simple experimental and work-up procedure.The mesoporous solid acid catalyst was directly prepared from phytic acid by microwave-sulfonation method without template.The phytic acid based solid acid was fully characterized by means of Fourier transform infrared spectroscopy(FTIR),Raman spectroscopy,X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),and transmission electron imcroscopy(TEM).The catalyst can be recovered and reused for at least five runs without significant impact on the product yields.     

One‐pot Solvent Free Synthesis of Some Tert‐indolylmethane Amine Derivatives by Fe(HSO4)3 as a Recyclable Catalyst

Solvent‐free synthesis of 3‐substituted indole derivatives by a one‐pot three‐component coupling reaction between aldehyde, N‐alkyl aniline and indole by Fe(HSO₄)₃ catalyzed is described. The noticeable features of this protocol are the simplicity of the procedure, easy synthesized, recyclable and inexpensive catalyst, no organic solvent and high yields in relatively short reaction times.