A simple and efficient method for solvent-free iodination of hydroxylated aromatic aldehydes and ketones using iodine and iodic acid by grinding method

<正>Green,mild and efficient iodination of hydroxylated aromatic aldehydes and ketones using iodine and iodic acid in the solidstate by grinding under solvent-free conditions at room temperature.This method provides several advantages such as environmentally friendly,short reaction times,high yields,non-hazardous and simple work-up procedure.     

Nano-Fe3O4-encapsulated silica particles bearing sulfonic acid groups as a magnetically separable catalyst for green synthesis of 1,1-diacetates

Sulfonic acid-functionalized silica-coated nano-Fe₃O₄particles (Fe₃O₄@SiO₂–SO₃H) serve as a novel heterogeneous catalyst for the synthesis of acylals by direct condensation of aldehydes with acetic anhydride under solvent-free conditions at room temperature in short reaction times and excellent yields. The catalyst could be easily separated from the final product using an external magnet and reused several times without consequential loss of reactivity.     

Protic guanidinium ionic liquid as a green and highly efficient catalyst for the synthesis of functionalized spirochromenes under solvent-free conditions

A simple and efficient method for the synthesis of functionalized spirochromenes is explained using protic guanidinium ionic liquid as a catalyst under solvent-free conditions at room temperature. This procedure is simple, clean, and excellent yields are obtained in short reaction times.     

N-磺酸基聚(4-乙烯吡啶)硫酸氢铵作为新型、高效、可重复使用的固体酸催化剂用于无溶剂条件下酰化反应(英文)

N-Sulfonic acid poly(4-vinylpyridinum) hydrogen sulfate has been developed as a recyclable solid acid catalyst for the acetylation of alcohols, phenols, thiols, and amines, as well as the 1,1- diacetylation of aldehydes under solvent-free conditions at room temperature. The acetylated products were formed in good to excellent yields over short reaction times, and the catalyst could be readily recovered by filtration and used several times without any discernible loss in activity. The hydrogen sulfate anion of the catalytic system was found to play a critical role in enhancing the reaction time and yield of the acetylation reaction.     

BF3·SiO2-catalyzed one-pot synthesis of α-aminophosphonates in ionic liquid and neat conditions

α-Aminophosphonates were synthesized in a simple and efficient method from the three-component condensation reaction of 5-amino 2,2-difluoro-1,3-benzodioxole, aromatic aldehydes, and diethyl phosphite by silica-supported boron trifluoride (BF₃·SiO₂) in ionic liquid ([bmim][HCl]) under solvent-free conditions at room temperature in good to excellent yields and short reaction times. The catalyst can be recovered and reused for several times without any significant loss of activity. It was observed that a homogeneous reaction medium proved beneficial for the yield of the reaction.     

ZnO-nanoparticle-promoted synthesis of polyhydroquinoline derivatives via multicomponent Hantzsch reaction

Abstract  

Zinc oxide nanoparticles are used as an effective and reusable catalyst for one-pot, four-component couplings of aldehydes, dimedone, active methylene compounds, and ammonium acetate to produce polyhydroquinoline derivatives under solvent-free conditions at room temperature. Compared with other methods, satisfactory results are obtained with high yields, short reaction times, and simplicity in the experimental procedure. The catalyst could easily be recycled and reused four times without noticeable decrease in catalytic activity.     

An expeditious synthesis of cyanohydrin trimethylsilyl ethers using tetraethylammonium 2-(carbamoyl)benzoate as a bifunctional organocatalyst

Phthalimide and tetraethylammonium hydroxide react via an unusual pathway to afford tetraethylammonium 2-(carbamoyl)benzoate (TEACB) which is of interest as a bifunctional organocatalyst. TEACB (0.5 mol %) was found to catalyze the addition of trimethylsilyl cyanide (TMSCN) to carbonyl compounds under solvent-free conditions at room temperature with very short reaction times. A wide variety of aldehydes and ketones were transformed into the corresponding cyanohydrin trimethylsilyl ethers in high to quantitative yields.     

Facile and green synthesis of triarylmethanes using silica sulfuric acid as a reusable catalyst under solvent-free conditions

A facile and environmentally-benign protocol has been developed for the synthesis of triarylmethanes (TAMs) from the reaction of different arenes and aldehydes in the presence of silica sulfuric acid (SSA) as a heterogeneous and reusable catalyst under solvent-free conditions. Easy work-up, short reaction times, high yields, high selectivity, mild and green conditions are other salient features of this method.     

Pseudo five-component process for the synthesis of functionalized tricarboxamides using CuI nanoparticles as reusable catalyst

An efficient and multicomponent method has been developed for the synthesis of functionalized tricarboxamides at room temperature using CuI nanoparticles as catalyst. This method involved fivecomponent coupling reactions of Meldrum's acid, isocyanides with aromatic aldehydes and amines at room temperature. Atom economy, wide range of products, excellent yields in short time and mild reaction conditions are some of the important features of this protocol. Notably, this catalyst could be recycled and reused for several times without significantly decreasing the catalytic activity.     

Copper(II) tetrafluoroborate as a novel and highly efficient catalyst for acetal formation

Commercially available copper(II) tetrafluoroborate hydrate has been found to be a highly efficient catalyst for dimethyl/diethyl acetal formation in high yields from aldehydes and ketones by reaction with trimethyl/triethyl orthoformate at room temperature and in short period. Acetalisation was carried out under solvent-free conditions with electrophilic aldehydes/ketones. For weakly electrophilic aldehydes/ketones (e.g., benzaldehyde, cinnamaldehyde and acetophenone) and for aldehydes having a substituent that can coordinate with the catalyst, the corresponding alcohol was used as solvent.     

Cupric Sulfate Pentahydrate: A Mild and Efficient Catalyst for the Chemoselective Synthesis of 1,1-Diacetates from Aldehydes in a Solvent-Free System

Cupric sulfate pentahydrate was found to be an efficient catalyst for the protection of aldehydes as 1,1-diacetates in high yields in a solvent-free system at room temperature. Ketones are not affected under these reaction conditions.     

Cupric Sulfate Pentahydrate: A Mild and Efficient Catalyst for the Chemoselective Synthesis of 1,1-Diacetates from Aldehydes in a Solvent-Free System

Summary. Cupric sulfate pentahydrate was found to be an efficient catalyst for the protection of aldehydes as 1,1-diacetates in high yields in a solvent-free system at room temperature. Ketones are not affected under these reaction conditions.     

An efficient, catalyst- and solvent-free, four-component, and one-pot synthesis of polyhydroquinolines on grinding

An efficient synthesis of polyhydroquinolines is achieved via a four-component reaction of aldehydes, dimedone, active methylene compounds, and ammonium acetate in one-pot under solvent-free conditions at room temperature on grinding. The present method does not involve any hazardous organic solvent or catalyst. The key advantages are the short reaction time, high yields, simple workup, and purification of products by non-chromatographic methods, i.e., by simple recrystallization from ethanol.     

One-pot, solvent-free regioselective addition reactions of propargyl bromide to carbonyl compounds mediated by Zn-Cu couple

A Barbier-type propargylation of carbonyl compounds with propargyl bromide has been achieved with reactive zinc-copper couple under solvent-free conditions. The reaction of aldehydes with propargyl bromide produced the unique homopropargyl alcohols in excellent yields at room temperature without the formation of homoallenyl alcohols. The ketones reacted with propargyl bromide to give the corresponding homopropargyl alcohols in good to excellent yields at −14 to −16 °C. The advantages of this method are excellent yields, short reaction time, high regioselectivity, and avoidance of the use of organic solvents.     

Efficient One-Pot Synthesis of Benzimidazoles Under Solvent-Free Conditions

A green, efficient method for the synthesis of various 2-aryl-benzimidazoles in the presence of hypervalent iodine as the oxidant at room temperature under solvent-free conditions is reported. The salient features of this method include mild conditions, short reaction times (3–5 min), excellent yields, and simple procedure.     

A facile one-pot synthesis of β-keto sulfones from ketones under solvent-free conditions

An easy solvent-free method is described for the conversion of ketones into β-keto sulfones in high yields that involves the in situ generation of α-tosyloxyketones, followed by nucleophilic substitution with sodium arene sulfinate in the presence of tetra-butylammonium bromide at room temperature. The salient features of this one-pot protocol are short reaction times, cleaner reaction profiles, and simple work-up that precludes the use of toxic solvents.     

Solvent-free synthesis of dihydropyrimidinones catalyzed by alumina sulfuric acid at room temperature

A simple, efficient and practical procedure for the Biginelli reaction using alumina sulfuric acid (ASA) as a novel acid catalyst is described under solvent-free conditions. The catalyst exhibited remarkable reactivity at room temperature. The method offers several advantages including high yields, environmentally friendly procedure, short reaction times and simple work up procedure.     

Highly efficient and green synthesis of 14-aryl(alkyl)-14H-dibenzo[a,j]xanthene and 1,8-dioxooctahydroxanthene derivatives catalyzed by reusable zirconyl triflate [ZrO(OTf)2]under solvent-free conditions

An efficient,convenient and green method has been introduced for the preparation of 14-aryl（alkyl）-14H-dibenzo[a,j]xanthene and 1,8-dioxooctahydroxanthene derivatives by the reaction of aldehydes with 2-naphthol and 5,5-dimethyl-1,3-cyclohexanedione, respectively,in the presence of ZrO（OTf）₂ as a reusable catalyst under solvent-free conditions.In addition,very short reaction times, excellent yields,straightforward procedure,and relatively non-toxicity of the catalyst are other noteworthy advantages of the present method.     

Synthesis of gem-Dihydroperoxides from Ketones and Aldehydes Using Silica Sulfuric Acid as Heterogeneous Reusable Catalyst

Silica sulfuric acid (SSA) was found to efficiently catalyze the conversion of aldehydes and ketones directly into the corresponding gem-dihydroperoxides (DHPs) on treatment with aqueous 30% H₂O₂ at room temperature. Mild reaction conditions, good to excellent yields, short reaction times, low environmental impact, and recyclability of the catalyst are the main advantages of this synthetic method.     

Urea nitrate–catalyzed C-N and C-S bond formation: A mechanochemical approach for 5-chloro-2-arylbenzo[d]thiazole derivatives

A series of substituted 5-chloro-2-arylbenzo[d]thiazoles were synthesized using 4-chloro-2-aminothiophenol and aromatic aldehydes in the presence of urea nitrate as a catalyst using the mechanochemical grindstone technique. This protocol was effectively carried out under metal-free conditions at room temperature, and the desired products were obtained in high to excellent yields in short reaction time (30–60 s). The structure of all the synthesized derivatives was confirmed by spectral characterization. The designed protocol has several benefits like eco-friendly, solvent-free, high yields, easy workup, and recyclability of catalyst. The catalyst was reusable at least four times without significant loss of activity. The good functional group tolerance with a series of derivatives has been demonstrated.