N-Sulfonic acid poly(4-vinylpyridinium) chloride as a highly effcient and reusable catalyst for the Biginelli reaction简

A mild, simple and efficient procedure for the preparation of 3,4-dihydropyrimidin-2（1H）-ones and -thiones is described using N-sulfonic acid poly（4-vinylpyridinium） chloride （NSPVPC） as a heterogeneous and efficient catalyst under solvent-free conditions. Simple methodologies, easy work-up procedure, easy preparation of the catalyst, excellent yields and very short reaction times are among the other advantages of this work. Further, the catalyst can be reused and recovered for several times without significant decrease in its activity.     

Efficient and green synthesis of dihydropyrimido[4,5-b]quinolinetriones using MWCNTs@TEPA/Co (II) as a novel and eco-friendly catalyst

A new heterogeneous nanocatalyst [MWCNTs@TEPA/Co (II)] was successfully prepared using multiwall carbon nanotubes (MWCNTs) as a suitable and efficient support for covalent anchoring of tetraethylene pentaamine (TEPA)/Co (II). The new heterogeneous catalyst was prepared through an easy and applicable method, and characterized by various techniques such as Fourier transform-infrared, thermogravimetric analysis, energy-dispersive X-ray spectroscopy, mapping, field emission-scanning electron microscopy, inductively coupled plasma-optical emission spectrometry and Brunauer−Emmett−Teller. Synthesized catalyst was used efficiently for the preparation of dihydropyrimido [4,5-b]quinolinetrione derivatives via the four-components reaction of barbituric acid, dimedone, aryl aldehyde and amines under thermal conditions. The nanostructure catalyst was easily recovered by filtration and reused several times without noticeable loss of its catalytic activity. Low amounts of catalyst (0.005 g), short reaction times and green conditions are some merits of the presented method.     

A novel polymeric catalyst for the one-pot synthesis of xanthene derivatives under solvent-free conditions

A simple, efficient, and environmentally benign route was developed for the preparation of 14-aryl or alkyl-14H-dibenzo[a,j]xanthene, 1,8-dioxo-octahydroxanthene and 12-aryl??8,9,10,12-tetrahydrobenzo[a]xanthene-11-ones from condensation of various aldehydes with (i) ??-naphthol, (ii) cyclic 1,3-dicarbonyl compounds and (iii) ??-naphthol and cyclic 1,3-dicarbonyl compounds, using novel polymeric catalyst [poly(AMPS-co-AA)] under solvent-free conditions. Use of easily available catalyst, shorter reaction times, better yields, simplicity of the reaction, heterogeneous system, and easy work-up are the advantages of the present method.     

Nucleophilic substitution reactions using Polyacrylamide-Based phase transfer catalyst in organic and aqueous media

Poly [N-(2-aminoethyl) acrylamido] trimemethyl ammonium chloride was prepared and used as an effective heterogeneous phase-transfer catalyst. This modified polyacrylamide catalyzed nucleophilic displacement of alkyl halides for easy preparation of alkyl thiocyanates, alkyl cyanides, alkyl azides, and alkyl aryl ethers in high yields and short reaction times in organic and aqueous media under two-phase and triphase conditions. The catalyst can be recovered and reused several times.     

Fe3O4–cysteamine hydrochloride magnetic nanoparticles: New,efficient and recoverable nanocatalyst for Knoevenagel condensation reaction

Fe₃O₄ magnetic nanoparticles (MNPs) were obtained using a reduction–precipitation method. These MNPs were modified with cysteamine hydrochloride. This catalyst was characterized using a number of physicochemical measurements. The Fe₃O₄–cysteamine MNPs, as an efficient and heterogeneous catalyst, were successfully used for Knoevenagel condensation under mild conditions. The activity of this nanomagnetic catalyst in the Knoevenagel condensation of aromatic aldehydes and malononitrile is described. Easy preparation of the catalyst, easy work‐up procedure, excellent yields and short reaction times are some of the advantages.     

Poly(vinylpyrrolidonium) perchlorate catalyzed one-pot synthesis of tricyclic dihydropyrimidine derivatives

A simple and efficient procedure for the synthesis of benzo[4,5]imidazo[1,2-α]pyrimidine and 2-amino-4-substituted-1,4-dihydrobenzo[4,5]imidazolo[1,2-α]pyrimidine-3-carbonitrile derivatives using poly(vinylpyrrolidonium) perchlorate {[PVPH]ClO₄} as a newly reported, modified polymeric catalyst is reported. Some of the advantages of this novel synthetic method are: easy preparation of the catalyst, simple and easy work-up procedure, short reaction times, high to excellent yields of the products and reusability of the catalyst.     

A general synthetic method for the formation of arylaminotetrazoles using natural natrolite zeolite as a new and reusable heterogeneous catalyst

An efficient method for preparation of arylaminotetrazoles is reported using natrolite zeolite as a natural catalyst. Generally, isomer of 5-arylamino-1H-tetrazole can be obtained from arylcyanamides carrying electron-withdrawing substituent on aryl ring and as the electropositivity of substituent is increased, the product is shifted toward the isomer of 1-aryl-5-amino-1H-tetrazole. This method has the advantages of high yields, simple methodology, short reaction times and easy work-up. The catalyst can be recovered by simple filtration and reused in good yields.     

NaY zeolite functionalized by sulfamic acid/Cu(OAc)2 as a new and reusable heterogeneous hybrid catalyst for efficient solvent-free formylation of amines

NaY zeolite functionalized by sulfamic acid/Cu(OAc)_2[NaY/SA/Cu(Ⅱ)] was synthesized and used as a new,efficient and recyclable catalyst for preparation of formamides. This novel organic-inorganic hybrid catalyst was characterized by several techniques such as FT-IR, XRD, SEM, EDX and TG analysis.Chemoselectivity, easy procedure, excellent yields, very short reaction times, solvent-free and mild reaction conditions are some benefits of this new protocol.     

N-Protection of amines using pyridinium 2, 2, 2-trifluoroacetate ionic liquid as an efficient and reusable catalyst

A simple, green, and efficient method for the N-tert-butoxycarbonylation of amines by pyridinium 2,2,2- trifluoroacetate （[Py][OTf]） as an efficient and reusable catalyst is reported. In general, electron donating groups on aryl group give rise to the higher yields than electron withdrawing groups. Clean reaction, short reaction times, high yields, reusability of catalyst, and easy preparation of it are some advantages of this work.     

Efficient four‐component synthesis of spiroindole derivatives catalysed by a versatile and reusable nano‐paramagnetic catalyst

A simple, efficient and environmentally benign route was developed for the preparation of spiro(indoline‐3,4‐pyrano[2,3‐c ]pyrazole) derivatives with good yields from condensation of isatins, malononitrile (or ethyl cyanoacetate), hydrazine hydrate and ethyl acetoacetate catalysed by PFu@Fe₃O₄ nanocomposite. The use of easily available catalyst, shorter reaction times, better yields, simplicity of reaction, heterogeneous system and easy work‐up are the advantages of the method presented. Characterization of the catalyst was performed using Fourier transform infrared spectroscopy, X‐ray diffraction and transmission electron microscopy.     

Silica Sulfate,an Efficient Catalyst for the Trimethylsilylation of Alcohols

An easy method for the preparation of trimethylsilyl ethers from alcohols and 1,1,1,3,3,3‐hexamethyl‐disilazane (HMDS) using silica sulfate as a catalyst under mild conditions in excellent yields is described.     

First sonochemical,simple and solvent-free synthesis of chiral tert-butanesulfinimines using silica supported p-toluenesulfonic acid

A solvent-free, versatile procedure has been developed for the effective synthesis of tert-butanesulfinylimines of a variety of aldehydes using chiral tert-butanesulfinamides under green, sonochemical conditions. This method utilizes silica supported p-toluenesulfonic acid (pTSA·SiO₂) as an efficient, safer and inexpensive catalyst under aerobic conditions. The practicable simplicity, easy preparation of the catalyst from readily available substances, high substrate scope, excellent yields of products in short reaction times and environmentally benign (solvent-free sonochemical) conditions are the exceptional assets of this finding.     

Polystyrene-supported TiCl4 as a novel,efficient and reusable polymeric Lewis acid catalyst for the chemoselective synthesis and deprotection of 1,1-diacetates under eco-friendly conditions

Copolymer beads of styrene and divinylbenzene (5–7%) were synthesized and combined with titanium tetrachloride in CS₂ to form a stable complex. The PS/TiCl₄ complex was used as a mild and efficient polymer-supported Lewis acid catalyst for the preparation of 1,1-diacetates from various types of aldehydes under heterogeneous conditions at room temperature. Deprotection of the resulting 1,1-diacetates has also been achieved using the same catalyst in methanol. This new protocol has the advantages of easy availability, stability, reusability of the eco-friendly catalyst, high to excellent yields, chemoselectivity, simple experimental and work-up procedure. Moreover, this polymeric catalyst could be recovered easily and reused several times without significant loss in activity.     

Magnetically‐recoverable Schiff Base Complex of Pd (II) Immobilized on Fe3O4@SiO2 Nanoparticles: An Efficient Catalyst for Mizoroki‐Heck and Suzuki‐Miyaura Coupling Reactions

The activity of Pd(II)‐Schiff base complex molecules grafted on the surface of Fe₃O₄@SiO₂ particles were investigated in the palladium‐catalyzed coupling reactions of aryl halides with alkenes (Mizoroki‐Heck reaction) and phenylboronic acids (Suzuki‐Miyaura reaction) in the absence of phosphorous ligands. This method shows notable advantages such as heterogeneous nature of the catalyst, excellent yields, short reaction times, easy preparation, simplicity of operation, and cleaner reaction profiles. The catalyst can be separated from the reaction mixture by applying a permanent magnet externally and can be reused for several times without significant loss of activity. Also, the amount of palladium leaching has been determined by ICP analysis.     

Sonosynthesis of spiroindolines using functionalized SBA-15

Functionalized SBA-15 (immobilization of Pd on the modified SBA-15) has been used as an efficient catalyst for the preparation of spiroindolines by multi-component reactions of isatins, cyclic-1,3-diketones, and 6-amino-1,3-dimethyluracil under ultrasonic irradiation in water. The catalyst has been characterized by X-ray diffraction spectroscopy (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), N₂ adsorption analysis, temperature-programmed desorption (TPD), and thermogravimetric analysis (TGA). The advantages of this method include the reusability of the catalyst, low catalyst loading, excellent yields in short reaction times and easy separation of products, and use of ultrasonic irradiation as a valuable and powerful technology.

     

Preparation and application of SBA-15-supported palladium catalyst for Heck reaction in supercritical carbon dioxide

A new method for the preparation of SBA-15-supported palladium catalyst for Heck reaction in supercritical carbon dioxide was presented.The newly formed SBA-15-supported palladium catalyst（Ph-SBA-15-PPh₃-Pd） exhibited high catalytic activity for the Heck reaction of 4-nitrobromobenzene with methyl acrylate.The catalyst can be reused several times without a loss of activity.     

ZnO as an Effective and Reusable Heterogeneous Catalyst for the Synthesis of Arylaminotetrazoles

ZnO is an effective heterogeneous catalyst for the reaction between arylcyanamides with sodium azide to synthesize the arylaminotetrazoles in good yields. This method has advantages of good yields, simple methodology, short reaction times, and easy workup. Furthermore, the catalyst can subsequently be reused for several times without any significant loss of activity.     

Integration of high speed microwave chemistry and a statistical ‘design of experiment’ approach for the synthesis of the mitotic kinesin Eg5 inhibitor monastrol

The rapid preparation of the mitotic kinesin Eg5 inhibitor monastrol has been performed using multicomponent chemistry and combining microwave-assisted synthesis and a statistical design of experiments (DoEs) approach. By variation of the solvent, catalyst type and concentration, reaction time, and temperature a matrix of experiments for the DoE method was derived. As a result of 29 experiments with reaction times ranging from 10 to 30 min, an optimized procedure was derived that allowed the preparation of monastrol in 82%.     

氧化镁负载三聚氰胺缩甲醛高分子钯配合物催化剂催化加氢制备葡辛胺的研究

以氧化镁负载三聚氰胺缩甲醛高分子钯配合物为催化剂, 对葡萄糖与正辛胺催化加氢制备葡辛胺进行了研究. 结果表明在以60 mL乙醇为溶剂, 三乙胺为添加剂(1.0 mL), 于60 ℃的反应温度, 1.5 MPa反应氢压, 0.7 g催化剂用量下反应6 h, 37.2 mmol葡萄糖与31 mmol正辛胺催化加氢可得产率为57.6%的葡辛胺. 相对于雷内镍催化剂, 该催化剂制备简单,制备过程无污染、对环境友好,产物纯度高,并具有适当的可重复使用,因此氧化镁负载三聚氰胺缩甲醛高分子钯配合物是葡辛胺制备的良好催化剂.     

从醛无溶剂制备1,1-二乙酸酯的催化剂Cu3/2PMo12O40/SiO2

芳香醛和脂肪醛在温和条件下经乙酸酐和Cu3/2PMo12O40/SiO2催化可转变成 1,1-二乙酸酯. 发现Cu3/2PMo12O40/SiO2是在无溶剂存在下制备 1,1-二乙酸酯的有效催化剂. 使用同一催化剂和乙腈作溶剂可使生成的 1,1-二乙酸酯发生逆反应脱保护生成醛. 这种新的方法具有反应时间短和收率高的优点,而且催化剂重复使用几次不丧失活性.