PEG‐Supported Sulfonic Acid as an Efficient and Recyclable Catalyst for the Synthesis of 1,1‐Diacetates under Solvent‐Free Conditions

An operationally simple, efficient, and environmentally benign synthesis of 1,1‐diacetates in good yields by reaction of different aldehydes with acetic anhydride in the presence of PEG‐supported sulfonic acid under solvent‐free conditions is described.     

Uncatalyzed and Solvent‐Free Process for the Synthesis of 1,4‐Diarylquinoline Derivatives

The uncatalyzed and three‐component reaction of arylaldehyde, malonodinitrile, and 3‐arylamino‐5,5‐dimethylcyclohex‐2‐enone at 160 °C under solvent‐free conditions gave 1,4‐diarylquinoline derivatives in high yields.     

InCl3 as an Efficient Catalyst for Cyclotrimerization of Aldehydes: Synthesis of 1,3,5‐Trioxane Under Solvent‐Free Conditions

1,3,5‐Trioxanes derived from aldehydes were synthesized using indium trichloride as a catalyst. Cyclotrimerization of the aldehydes gave excellent yields under neat conditions within a short span of time.     

Sulfamic Acid as a Cost‐Effective and Recyclable Catalyst for Protection of Carbonyls to Acetals and Ketals Under Mild Conditions

Abstract

An efficient H₂NSO₃H‐catalyzed protection of various carbonyl compounds at room temperature was investigated. The features of mild conditions, cost‐efficient catalyst, simple workup, and the recyclability of the catalyst were represented in this process.     

Porous Calcium Hydroxyapatite as an Efficient Catalyst for Synthesis of Pyrazolines via 1,3‐Dipolar Cycoloaddition Under Solvent‐Free Microwave Irradiation

Adsorbed on porous calcium hydroxyapatite, 1,3‐dipolar cycloaddition of diphenylnitrilimine on olefins is readily catalyzed under solvent‐free microwaves irradiation. The pyrazolines are obtained in few minutes with high yields. Specific surface of porous calcium hydroxyapatite and microwaves effects are discussed.     

Synthesis of New β-Acetamido Carbonyl Derivatives Using Cellulose Sulfuric Acid as an Efficient Catalyst

New β-acetamido ketone derivatives are synthesized through a one-pot, four-component reaction of benzaldehyde, dimedone, acetyl chloride, and acetonitrile in the presence of cellulose sulfuric acid as an efficient reusable catalyst. The procedure offers advantages in terms of good yields, short reaction times, mild reaction conditions, and reusability of the catalyst.     

Solvent‐Free Synthesis of Benzothiazolines in the Presence of Alumina

o‐Aminothiophenol reacted with ketones and β‐keto esters in the presence of alumina under mild and solvent‐free conditions to afford the corresponding benzothiazolines in high yields. Alumina can be reused for subsequent reactions without any loss of the activity.     

Microwave‐Assisted Efficient Synthesis of Dihydropyrimidines in Solvent‐Free Condition

Abstract

An efficient synthesis of 3,4‐dihydropyrimidinones from an aldehyde, a ketoester, and a urea or thiourea using a catalytic amount of ferric chloride hexahydrate is described. Microwave irradiation has been used to accelerate the synthesis of the Biginelli compounds under solvent‐free conditions and in a short reaction time and with good yield.     

Microwave-prompted Rapid and Efficient Synthesis of Diacyl Thiosemicarbazides and Semicarbazides in Solvent and Catalyst Free Condition

Eighteen 1-aroyl-4-（2-iodobenzoyl）thiosemicarbazides and corresponding semicarbazides were synthesized in excellent yield under microwave irradiation in solvent and catalyst free condition.     

Solvent‐Free Synthesis of Arylamides and Arylimides,Analogues of Acetylcholine

Abstract

Several arylamides and arylimides, novel inhibitors of acetylcholinesterase, were obtained under solventless conditions; the target molecules were produced with a good overall yield and short reaction times.     

Convenient and Regioselective One‐Pot Solvent‐Free Synthesis of ß‐Hydroxyphosphonates

A simple, efficient, regioselective, and solvent‐free method has been developed for the synthesis of β‐hydroxyphosphonates from epoxides and triethyl phosphite using ZnCl₂ in high yields under mild conditions.     

Dodecatungstophosphoric Acid (H3PW12O40): A Novel and Efficient Recyclable Catalyst for Synthesis of 1,1‐Diacetates from Aromatic Aldehydes in Solvent‐Free System and Their Deprotection

A facile and efficient method for the formation of 1,1‐diacetates from a variety of aldehydes in the presence of a catalytic amount of H₃PW₁₂O₄₀ and acetic anhydride was achieved in good yields at room temperature. The deprotection of the resulting acylals is achieved using the same catalyst in acetone.     

A Mild and Efficient Synthesis of bis‐Indolylmethanes Catalyzed by Sulfamic Acid

A mild and efficient electrophilic substitution reaction of indoles with various aldehydes under catalysis of sulfamic acid afforded biologically important bis‐indolymethanes in good yields.     

Microwave‐Assisted Solvent‐Free Regiospecific Synthesis of 5‐Alkylidene and 5‐Arylidenehydantoins

Hydantoins have become a well‐known class of structures that have found significant applications as agrochemicals and therapeutics. This structural motif is of interest in the synthesis of small building blocks suitable for the preparation of potentially bioactive molecules. In this sense, 5‐alkylidene and 5‐arylidenehydantoins constitute nice examples of precursors of synthetic α‐amino acids. The microwave‐assisted synthesis of these compounds under green chemistry conditions is reported in this article. The method has proved to afford yields of 74–96%.     

Synthesis of β‐Phenylchalcogeno‐α,β‐unsaturated Ketones via Hydrochalcogenation of Acetylenes using Microwave and Solvent‐Free Conditions

A simple, clean, and efficient solvent‐free protocol was developed for hydrochalcogenation of 3‐organyl‐3‐butyn‐2‐ones with phenylchalcogenolate (Se, Te, S) anions generated in situ from the respective diphenyl dichalcogenide using alumina‐supported sodium borohydride (Se, Te) or commercially available (S). This efficient and improved method is general and furnishes the (Z)‐β‐phenylchalcogeno‐α,β‐unsaturated ketones in good yield with higher selectivity compared with those that use organic solvent and an inert atmosphere. The use of microwave (MW) irradiation facilitates the procedure and accelerates the reaction.     

Solvent‐Free Synthesis of Ethyl α‐Cyanocinnamate in the Presence of CaO

Abstract

Ethyl α‐cyanocinnamate can be prepared by grinding in the presence of CaO at room temperature. This method is simple, efficient, economical, and environmentally benign.     

One‐Pot Synthesis of Iminoimidazolines under Microwave Irradiation in Solvent‐Free Conditions

Substituted iminoimidazolines were synthesized from a one‐pot reaction of aromatic or hetero‐aromatic amines with imidazolidine‐2‐thione under solvent‐free conditions using microwave irradiation with good to excellent yields.     

Catalyst‐free Efficient Synthesis of 3‐Thio‐2‐deoxysugar Derivatives in Water

3‐Thio‐ and 3‐dithiocarbamoyl‐2‐deoxy carbohydrate derivatives have been synthesized using water as solvent without using a catalyst. In most of the cases yields obtained were excellent.     

Diammonium Hydrogen Phosphate as a Neutral and Efficient Catalyst for Synthesis of 1,8‐Dioxo‐octahydroxanthene Derivatives in Aqueous Media

A new and efficient method to synthesize a 3,3,6,6,9‐aryl‐1,8‐dioxo‐octahydroxanthene derivative using diammonium hydrogen phosphate as catalyst was performed in water at room temperature in a short periods.     

Solvent‐Free Rapid Deprotection of Ketone and Aldehyde Oximes using Periodic Acid

Abstract

Ketone and aldehyde oximes can be readily converted to the corresponding carbonyl compounds in high yields under solvent‐free conditions when treated with periodic acid. Oximes bearing aliphatic C?C bonds can be selectively deoximated. The advantages of this protocol include a rapid reaction rate and a simple workup procedure. No volatile organic solvents are required in the reaction processes.