Ionic liquid catalyzed synthesis of 7-phenyl-1,4,6,7-tetrahydro-thiazolo[5,4-d]pyrimidine-2,5-diones

A simple, green and catalyst free one pot synthesis of 7-phenyl-1,4,6,7-tetrahydro-thiazolo[5,4-d]pyrimidine-2,5-diones via a multicomponent reaction between thiazolidine-2, 4-dione (TZD), aromatic aldehyde and urea analogues is described. The ionic liquid has been used as a solvent as well as catalyst for this reaction. This reaction proceeded smoothly in good to excellent yields and offered several other advantages including short reaction time, simple experimental workup procedure and no by-products.     

Synthesis of bioactive heterocycles using reusable heterogeneous catalyst HClO4–SiO2 under solvent-free conditions

We are reporting a simple, efficient and green protocol for the synthesis of chromenes and dihydropyrimidines (products of Knoevenagel and Biginelli reaction, respectively) by the use of silica-supported perchloric acid (HClO₄–SiO₂) as an effective heterogeneous catalyst. Short reaction times, high product yields, simple procedure and reusability of the catalyst are the superior characteristics of this protocol.     

Aqueous media preparation of 2-amino-4,6-diphenylnicotinonitriles using cellulose sulfuric acid as an efficient catalyst

A convenient approach to the synthesis of 2-amino-4,6-diphenylnicotinonitriles via four-component reaction of aromatic aldehydes, acetophenone derivatives, malononitrile and ammonium acetate is described. The reactions were done in water as solvent using cellulose sulfuric acid as catalyst. This simple protocol offer advantages such as shorter reaction times, simple work-up procedure, excellent yields and catalyst recovery.     

Synthesis of aryl substituted quinones as β-secretase inhibitors: Ligand-free direct arylation of quinones with aryl halides

The simple ligand-free direct arylation of quinones with aryl halides applying Pd(OAc)₂ as a catalyst in accordance with Heck reaction was studied. This reaction provided a simple and efficient synthetic approach to efficient inhibitors of β-secretase aryl-substituted quinones.     

Cooperative catalysis: Condensation-aromatization for synthesis of 2-(4-nitrophenyl)-1H-benzimidazole by silica immobilized Brønsted-Lewis acidic ionic liquid (Si-BLAIL)

Herein, pleasing the advantageous of both Brønsted and Lewis acidic site of Si-BLAIL the condensation-aromatization reaction has been carried out. The striking distinctiveness of work is optimum reaction condition, easy work-up, high yield, catalyst recyclability, non-inertness of reaction flask, simple catalyst loading method. The decreases in the amount of catalyst and reaction time shows good to high (71%–93%) yield suggests about the involvement of some interesting mechanism such as cooperative catalysis. The mechanism has been hypothesizes as, the Si-BLAIL increase the efficiency of condensation reaction possibly by providing the proton in 2-position of cationic imidazolium ring of BLAIL through the hydrogen bond interaction with carbonyl group and nucleophilic activation during aromatization by hydrogen bond acceptor ability of Lewis adduct anion of BLAIL. The catalyst Si-BLAIL shows massive affirm for industrial applications. The Si-BLAIL has identified as the best acid catalyst for 2-(4-nitrophenyl) benzimidazole synthesis with additional benefits of cooperative catalysis.     

Al(HSO4)3: an efficient and heterogeneous reusable catalyst for the synthesis of 1-amidoalkyl-2-naphthols under thermal solvent-free conditions

An efficient green protocol for the synthesis of 1-amidoalkyl-2-naphthols using a three-component, one-pot condensation reaction of 2-naphthol, aromatic aldehyde and amides in the presence of Al(HSO₄)₃ as heterogeneous catalyst under thermal solvent-free conditions has been described. The present procedure offers advantages such as shorter reaction times, simple work-up procedure, excellent yields, recovery and reusability of catalyst.     

Cellulose sulfuric acid catalyzed one-pot three-component synthesis of imidazoazines

Imidazoazines have been synthesized by a one-pot three-component condensation reaction of an aldehyde, a 2-aminoazine and an isocyanide in the presence of the cellulose sulfuric acid, as an effective bio-supported catalyst in excellent yields. The reaction work-up is simple and the catalyst can be easily separated from the product and reused in several times.     

Catalytic asymmetric dihydroxylation using phenoxyethoxymethyl-polystyrene (PEM)-based novel microencapsulated osmium tetroxide (PEM-MC OsO4)

[reaction: see text]. A phenoxyethoxymethyl-polystyrene (PEM)-based novel polymer-supported osmium catalyst has been developed. The catalyst was readily prepared from PEM polymer based on a microencapsulation technique, and asymmetric dihydroxylation of olefins has been successfully performed using (DHQD)2PHAL as a chiral ligand and K3Fe(CN)6 as a cooxidant in H2O/acetone. The catalyst was recovered quantitatively by simple filtration and reused without loss of activity several times.     

Environmentally Friendly Preparation of 3,4-Dihydropyrimidin-2(1H)-thiones Catalyzed by Al(H2PO4)3

An efficient, facile, simple, and green synthetic protocol for the Biginelli reaction has been developed for the preparation of 3,4-dihydropyrimidin-2(1H)-thione derivatives under thermal and microwave irradiation, solvent-free conditions, in the presence of aluminum hydrogen phosphate, Al(H₂PO₄)₃, as an environmentally friendly heterogeneous recyclable catalyst, in high to excellent yields and short reaction time. In addition, the catalyst could be easily recovered from the reaction mixture by simple filtration and reused several times without any loss of activity.     

全氟磺酸钯树脂催化的芳基卤与烯烃或炔烃的反应

全氟离子交换树酯[Perfluoririnted ion-exchange resin(PFIER)]由于其化学稳定性极好,因此用它作为高分子载体具有独特的优越性。全氟磺酸树脂作为强酸性催化剂,在有机合成中的应用已有广泛的研究。近年来,用高分子载体催化剂代替传统的小分子催化剂进行反应,由于后处理和催化剂回收方便而受到重视。但是,用含金属或金属阳离子的离子交换树脂作为金属催化剂参与的反应却研究得很少。     

Reusable nano-sized chiral bisoxazoline catalysts

The nano-sized gold particle-based chiral catalyst having two kinds of alkyl thiol spacers, one of which is substituted with the chiral bisoxazoline/copper(II) complex at the end, behaves as reusable homogeneous catalyst. This gold particle complex acts as nearly homogeneous catalyst in the ene reaction between 2-phenylpropene and ethyl glyoxylate in dichloromethane, while it undergoes dense aggregation when diluted with hexane so as to be separated by simple filtration. Thus, the catalyst can be recovered after the completion of reaction by the repeated sequences of solvent exchange, centrifugal treatment, and decantation, followed by the recharge of substrates, and the situation is ready for the second reaction.     

水溶性salen-Co(Ⅲ)配合物催化的端炔水合反应

报道了一种用于端炔水合反应的水溶性salen-Co(III)配合物催化剂,在使用硫酸作为共催化剂的条件下能高效得到产物甲基酮.该催化剂用量少,反应结束后可利用简单的萃取实现产物与催化剂分离,简化了后处理过程.此外,催化剂还可回收重复使用,但催化剂活性会略有下降.     

SnCl2/nano SiO2：A green and reusable heterogeneous catalyst for the synthesis of polyfunctionalized 4H-pyrans

A highly efficient and general method for the synthesis of polyfunctionalized 4H-pyrans is established through a one-pot multicomponent cyclocondensation of aromatic aldehydes with CH acids, malononitrile and ethyl acetoacetate using nano silica supported tin (Ⅱ) chloride as a catalyst. In this method SnCl2/nano SiO2 was used as green and reusable catalyst. Excellent yields, short reaction times, simple workup, and inexpensiveness and commercially availability of the catalyst are the advantages of this method.     

Sonochemical synthesis of 2,3-dihydro-4(1<Emphasis Type="Italic">H</Emphasis>)-quinazolinones and 1-amidoalkyl-2-naphthols using magnetic nanoparticle-supported ionic liquid as a heterogeneous catalyst

Ultrasound-promoted synthesis of 2,3-dihydro-4(1H)-quinazolinones and 1-amidoalkyl-2-naphthols were carried out using magnetic nanoparticle-immobilized ionic liquid (IL@MNP) as a magnetically separable catalyst. Ultrasound accelerates the reaction at ambient temperature making the protocol clean, simple and greener compared to conventional procedures. The catalyst showed high activity and stability during the reaction. The heterogeneous nature of the catalyst enabled easy recovery through an external magnet and it was reused up to six times without the loss of its activity. The synergistic effect of IL@MNP and ultrasound facilitate the reaction with excellent isolated yield in a shorter reaction time.     

One-pot synthesis of dihydropyrimidiones catalyzed by strontium(II) triflate under solvent-free conditions

A simple, efficient and practical procedure for the Biginelli reaction using strontium(II) triflate [Sr(OTf)₂] as a novel catalyst is described under solvent-free conditions in high yields. The catalyst exhibited remarkable reactivity and it is reusable. Some of dihydropyrimidiones showed strong pesticidal activity.     

水介质中N-芳基-N'-(2-苯并呋喃甲酰基)硫脲及1-芳甲酰基-4-(2'-苯并呋喃甲酰基)氨基硫脲的合成

苄基三乙基氯化铵(TEBA)存在的水介质中, 2-苯并呋喃甲酰氯、硫氰酸铵与芳胺或芳甲酰肼在室温条件下经一步反应合成N-芳基-N'-(2-苯并呋喃甲酰基)硫脲或1-芳甲酰基-4-(2'-苯并呋喃甲酰基)氨基硫脲, 其中前者尚未见文献报道. 与其它合成方法相比, 该法操作简单、反应条件温和、环境友好.     

由2-羟基-1,4-萘醌合成2-乙氧基-1,4-萘醌

由2-羟基-1;4-萘醌合成2-乙氧基-1;4-萘醌;乙氧基萘醌; 羟基萘醌; 乙醇; 硝酸; 回流     

Sustainable synthesis of [1]benzopyran azo dyes using CuCr2O4 NPs

In this study, copper chromite nanoparticles (CuCr₂O₄ NPs) were prepared by a simple hydrothermal method. This nanomaterial was found as an efficient heterogeneous catalyst for the synthesis of a new class of [1]benzopyran azo dyes via pseudo-three-component reaction of (E)-1,2-diphenyl-1-diazene with 4-hydroxycoumarin in the ratio 1:2. The aim of the present work was to provide a practical and high yielding protocol that offers several advantages such as simple procedure with an easy work-up, mild reaction conditions, and the use of CuCr₂O₄ NPs as an efficient and easily recoverable catalyst.     

Green synthesis of 3,4-dihydropyrimidinones using nano Fe3O4@meglumine sulfonic acid as a new efficient solid acid catalyst under microwave irradiation

Design, synthesis and characterization of nano Fe₃O₄@meglumine sulfonic acid as a new solid acid catalyst for the simple and green one pot multicomponent synthesis of 3,4-dihydropyrimidin-2(1H)-ones/thiones was studied. New solid acid catalyst was prepared through a clean and simple protocol and characterized using FTIR, VSM, TGA, SEM, elemental analysis (CHN) and XRD techniques. Heterogenization of homogeneous catalyst as a green approach is a useful method for enhancing the efficiency of catalyst. Presented study was a new method for attachment of homogeneous highly soluble catalyst (meglumine sulfate) to the magnetite nanoparticle surfaces for preparing a heterogeneous and effective catalyst. Obtained heterogeneous and reusable solid acid catalyst has high performance in the synthesis of Biginelli compounds. The reaction was performed under microwave irradiation as a rapid and green condition. Easy work up as well as excellent yield (90–98%) of products in short reaction times (40–200 s) and reusable catalyst are the main advantages of presented procedure. Reaction products were characterized in details using physical and chemical techniques such as melting point, ¹H NMR, ¹³C NMR and FTIR.     

ZrO2催化无溶剂条件下醇的液相氧化反应

采用一种环境友好的方法,以分子氧为氧化剂,以ZrO2为催化剂,在无溶剂的条件下实现了醇的选择性氧化.苯甲醛、环己酮和辛醛等是相应醇的主要氧化产物.考察了不同反应条件(搅拌速度、反应时间和温度)、催化剂制备参数(焙烧温度和负载量)及氧分压等的影响.结果发现,对于醇氧化生成相应羰基化合物,1 223 K焙烧的ZrO2比723 K焙烧的ZrO2显示出更高的催化活性.催化剂在反应混合物中不溶解,可以通过简单的过滤使其分离并重复使用.当搅拌速度大于900 r/min时,对醇的转化速率无明显的影响.