Al(H2PO4)3 as an efficient and reusable catalyst for the multi-component synthesis of highly functionalized piperidines and dihydro-2-oxypyrroles

Extremely facile and efficient procedures have been developed for the synthesis of highly functionalized piperidines and dihydro-2-oxypyrroles via one-pot multi-component reactions in the presence of Al(H₂PO₄)₃ as a heterogeneous and eco-friendly catalyst under mild conditions. The multi-component reaction of aromatic aldehydes, aromatic amines, and β-keto esters catalyzed by Al(H₂PO₄)₃ in EtOH at room temperature provides highly functionalized piperidines in good to excellent yields. The structure as well as the relative stereochemistry of these functionalized piperidines was confirmed by single X-ray crystallographic analysis. The same catalyst was found useful for the synthesis of polyfuntionalized dihydro-2-oxypyrroles using a four-component reaction of amines, dialkyl acetylenedicarboxylates and formaldehyde in MeOH at ambient temperature. It is found that the catalyst is recyclable and can be used up to five times without significant loss of its activity.     

A metal-free C–C/C–O bond formation for the synthesis of 2-amino-5-oxo-4-aryl-4H,5H-pyrano[3,2-c]chromene-3-carboxamide catalyzed by polystyrene-supported p-toluenesulfonic acid (PS-PTSA)

An efficient and eco-friendly procedure for the synthesis of 2-amino-5-oxo-4-aryl-4H,5H-pyrano[3,2-c]chromene-3-carboxamide has been developed through a one-pot three-component condensation of 4-hydroxycoumarin with aldehydes and cyanoacetamide, in the presence of catalytic amount of polystyrene-supported p-toluenesulfonic acid (PS-PTSA) as a highly active and reusable heterogeneous acid catalyst in EtOH at 80?°C conditions. This new procedure offers several advantages such as shorter reaction times, excellent yields, a wide range of functional group tolerance, easy experimental work-up procedure, operationally simple under metal-free reaction conditions and C-C/C-O bond formation. The catalyst can be recovered and reused for at least four runs without any significant impact on the product yields.     

P2O5 mediated rapid condensation of 2-aminothiophenol with aromatic aldehydes at ambient temperature

<正>2-Arylbenzothiazoles formed in good yields(65-90%) by the condensation of aminothiophenols with aromatic aldehydes using P_2O_5 at ambient temperature.     

Strontium chloride-catalyzed one-pot synthesis of 4(3H)- quinazolinones under solvent-free conditions

<正>Strontium chloride was used as an efficient and recyclable catalyst in one-pot condensation of anthranilic acid,ortho esters and amines leading to the formation of 4(3H)-quinazolinone derivatives in good yields at room temperature under solvent-free conditions.     

Nano-tube TiO_2 as a new catalyst for eco-friendly synthesis of imines in sunlight

Nanomaterials are considered as suitable heterogeneous catalysts for many organic reactions.Herein nano-tube TiO₂ has been reported as a heterogeneous catalyst,for synthesis of imines in sunlight at room temperature under solvent-free conditions.The condensation of less electrophilic carbonyl compounds with poorly nucleophilic amines was afforded imines in excellent yields.     

Synthesis of 2,3-dihydroquinazolin-4(1H)-ones catalyzed by zirconium (IV) chloride as a mild and efficient catalyst

2, 3-Dihydroquinazolin-4 (1H)-ones have been synthesized in the high to excellent yields via condensation of 2-aminobenzamide with aldehydes and ketones in the presence of catalytic amount of ZrCl₄ in EtOH at room temperature. Mild reaction conditions, clean reaction media, simple workup and easy purification are advantages of this methodology.     

Rapid and straightforward one-pot expeditious synthesis of 2-amino-5-alkylidene-thiazol-4-ones at room temperature

A new methodology has been developed towards the room temperature synthesis of novel 2-amino-5-alkylidenethiazol-4-ones from aldehydes, amines and rhodanine in one-pot. A heterogeneous dipolar catalyst has been utilized for this reaction. The unique properties of this catalyst effectively synthesize such compounds at room temperature in contrast to all earlier reports.     

Synthesis of 2,3-dihydroquinazolin-4(1H)-ones catalyzed by zirconium(Ⅳ) chloride as a mild and efficient catalyst

2,3-Dihydroquinazolin-4(1H)-ones have been synthesized in the high to excellent yields via condensation of 2-aminobenzamide with aldehydes and ketones in the presence of catalytic amount of ZrCl_4 in EtOH at room temperature.Mild reaction conditions, clean reaction media,simple workup and easy purification are advantages of this methodology.     

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.     

A Ce(III)-catalyzed expeditious multicomponent stereoselective synthesis of 3-mercapto-2(1H)-pyridinones

A novel Ce(III)-catalyzed, convenient, expeditious, and diastereoselective synthesis of 3-mercapto-2(1H)-pyridinones via one-pot, [3+2+1] three-component coupling reactions of chalcones, 2-methyl-2-phenyl-1,3-oxathiolan-5-one, and amines is reported. The synthesis involves sequential Michael addition, condensation, and ring transformation. Ambient temperature, operational simplicity, use of an environmentally clean catalyst, high yields, and diastereoselectivity are the key features of the present synthetic protocol.     

ZrOCl2·8H2O as a highly efficient,eco‐friendly and recyclable Lewis acid catalyst for one‐pot synthesis of N‐substituted pyrroles under solvent‐free conditions at room temperature

A new and efficient method for the synthesis of a variety of N‐substituted pyrroles from condensation reactions of 2,5‐hexanedione with amines or diamines using ZrOCl₂·8H₂O as a water‐tolerant Lewis acid catalyst at room temperature is described.The use of nontoxic, inexpensive, easily available and reusable catalyst under solvent‐free conditions make this protocol practical, environmentally friendly and economically attractive. Copyright © 2011 John Wiley & Sons, Ltd.     

Facile synthesis of 2-carboxanilido-3-arylquinazolin-4-ones from N1-(2-carboxyphenyl)-N2-(aryl)oxalamides

A simple and efficient approach for the synthesis of novel 2-carboxanilido-3-arylquinazolin-4-ones via the one-pot condensation of readily available N¹-(2-carboxyphenyl)-N²-(aryl)oxalamides with various aromatic amines is described. Notably, this methodology allows us to synthesize 3-aryl-quinazolin-4-ones using aromatic amines with various substituents, both electron-donating and electron-withdrawing, which ensures structural diversity of the products and an atomic-economic process.     

Au/Al2O3催化剂的制备及其在CH4/CO2重整反应中的催化活性

采用浸渍法和沉积－沉淀法制备了四种不同的Au/Al2O3催化剂，测定了它们在氢气还原前后及催化反应后的金含量及比表面积，结果表明，制备方法明显影响催化剂的金含量，应用X－光粉末衍射技术研究了这些催化剂经还原处理及反应后的物相变化，金以Au^0物相存在，没有发现氧化态的金物相，考察了该催化剂在CH4／CO2重整反应中的催化活性，发现金催化剂的活性取决于金粒子的大小，浸渍法制备的金催化剂具有较大的金晶粒尺寸，催化活性低，沉积－沉淀法制备的金催化剂金晶粒尺寸较小，催化活性较高，以尿素为沉淀剂制备的催化剂给出1073K时的CH4和CO2转化率分别为8．1％和17．6％，高温反应不仅导致金晶粒的聚集，而且存在明显的金流失现象。     

NaHSO4•SiO2催化合成β-烯胺酮(酯)

NaHSO₄•SiO₂作催化剂, 1,3-二羰基化合物和伯胺在室温下反应合成了一系列β-烯胺酮(酯), 该法反应条件温和, 产率高, 催化剂能回收再利用.     

Magnetic CuO nanoparticles supported on graphene oxide as an efficient catalyst for A3-coupling synthesis of propargylamines

Magnetically separable CuO nanoparticles supported on graphene oxide (Fe₃O₄ NPs/GO-CuO NPs) is synthesized and characterized for the preparation of propargylamines in EtOH, at 90℃. Fe₃O₄ NPs/GO-CuO NPs is found to be an efficient catalyst for the A³-coupling of aldehydes, amines, and alkynes through C-H activation. Both aromatic and aliphatic aldehydes and alkynes are combined with secondary amines to provide a wide range of propargylamines in moderate to excellent yields.     

Sulfamic Acid as a Cost‐Effective and Recyclable Catalyst for β‐Amino Carbonyl Compounds Synthesis

Sulfamic acid was used as a catalyst in the synthesis of β‐amino carbonyl compounds from amines, acetophenone and aldehyde. The reaction was carried out at room temperature. High selectivity, mild reaction temperature, cost‐effective catalyst, simple product separation and catalyst recycle were notable achievements in the reaction. Another feature was that the reaction could be performed on a relatively larger scale to the model reaction (50 times), which also gave good yields. In particular, the first preparation of β, β'‐diamino diketone derivatives via the direct coupling of amines, acetophenone and isophthalic aldehyde promoted by sulfamic acid has been developed.     

Clean synthesis of 2-arylideneindan-1,3-diones in water

A high-yield synthesis of 2-arylideneindan-1,3-diones in water was achieved by the Knoevenagel condensation of indan-1,3-dione with aromatic aldehydes at ambient temperature avoiding the addition of any catalyst. The procedure is simple, efficient, as well as environmentally friendly.     

A cesium fluoride promoted efficient and rapid multicomponent synthesis of functionalized 2-amino-3-cyano-4H-pyran and spirooxindole derivatives

A rapid, one-pot and highly efficient protocol for the synthesis of pharmaceutically interesting functionalized 2-amino-3-cyano-4H-pyran and spirooxindole derivatives has been developed using commercially available Cs F as a catalyst in the reaction of malononitrile and aryl aldehydes or isatins with 1,3-cyclohexanediones. The major advantages of this methodology are excellent yield at ambient temperature, very short reaction time(5–10 min), and use of an inexpensive catalyst.     

Preparation of 2-amino-5,7-dimethoxy-4-aryl/alkyl-4H-chromene-3-carbonitriles using Na_2O-Al_2O_3-P_2O_5 glass–ceramic system

A highly efficient and environmentally benign protocol for the synthesis of 2-amino-5,7-dimethoxy-4-aryl/alkyl-4H-chromene-3-carbonitrile derivatives by one-pot three-component coupling reacting of aromatic aldehydes, malononitrile and 3,5-dimethoxy phenol under reflux condition has been developed in aqueous Et OH media using Na2O-Al2O3-P2O5glass–ceramic system.     

Nucleophilic Addition of Amines to N-Aryl-substituted Pyrrolin-2-ones

The nucleophilic addition of n-butyl- and benzylamines to 1-(4-nitrophenyl)-5H-pyrrolin-5-one and 1-(4-sulfamoylphenyl)-5H-pyrrolin-2-one at 50°C in an excess of the amines with the formation of N-substituted amides of 3-alkyl(benzyl)amino-4-(4-R-anilino)butyric acids was investigated. The N-substituted amides of 3-arylamino-4-hydroxybutyric and 4-hydroxy-2-butenoic acids were synthesized from 2(5H)-furanone and aromatic amines (1:3) at 180°C. 4-Alkylamino-1-(4-nitrophenyl)pyrrolid-2-ones were obtained in the reaction of 1-(4-nitrophenyl)-5-pyrrolin-2-one with ammonia or aliphatic, alicyclic, and aromatic amines (1:3, 90°C, in DMF).