Solvent-free,four-component synthesis of 3,4,7,8-tetrahydro-3,3-dimethyl-11-aryl-2<Emphasis Type="Italic">H</Emphasis>-pyridazino[1,2-a]indazole-1,6,9(11<Emphasis Type="Italic">H</Emphasis>)-triones; using 1-butyl-3-methylimidazolium hydroxide ([bmim]OH) as a green and reusable catalyst

A series of 3,4,7,8-tetrahydro-3,3-dimethyl-11-aryl-2H-pyridazino[1,2-a]indazole-1,6,9(11H)-trione derivatives have been synthesized via one-pot, four-component reaction in the presence of 3-methyl-1-butyl imidazolium hydroxide as an efficient catalyst. A broad range of structurally diverse aldehydes (aromatic aldehydes bearing electron withdrawing and electron releasing groups) was applied successfully, and corresponding products were obtained in good to excellent yields without any by-product. The catalyst was stable during the reaction process and could also be reused several times with consistent activity.     

聚(4-乙烯基吡啶丁烷磺酸)硫酸氢盐:一个高效的多相聚(离子液体)固体酸催化剂用于无溶剂条件下一锅法合成1-酰氨基-2-萘酚和取代喹啉(英文)

Poly(4-vinylpyridinium butane sulfonic acid) hydrogen sulfate has been used as an efficient dual acidic catalyst for the one-pot preparation of 1-amidoalkyl-2-naphthols and substituted quinolines under solvent-free conditions.The catalyst was characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, and thermo-gravimetric analysis. The results revealed several advantages to our new catalyst system,including its reusability,facile work-up procedure, eco-friendly reaction conditions,short reaction time,and high product yields.     

KF负载氧化物高效催化缺电子烯与胺类的共轭加成反应

提供了一种新型高效的催化缺电子烯与胺类的共扼加成的反应体系。首先合成了一系列负载型氟化钾固体碱,并用于催化上述反应。通过对不同载体选择考察,筛选出氟化钾负载氧化镁固体碱为最佳催化剂。在进一步的催化反应过程中发现,该催化剂对反应具有很高的催化活性,能催化该反应在短短数分钟内完成。操作简单方便,不需要任何溶剂,催化剂价格低廉,反应收率高,可重复使用,具有化学选择性,适用范围广泛等均为该催化体系的主要特征。     

(Triazinediyl)bis sulfamic acid-functionalized silica-coated magnetite nanoparticles: Preparation,characterization and application as an efficient catalyst for synthesis of mono-, bis-, tris- and spiro-perimidines

(Triazinediyl)bis sulfamic acid-functionalized silica-coated magnetite nanoparticles have been prepared and applicated as an efficient catalyst for synthesis of mono-, bis-, tris- and spiro-perimidines. The desired products have been synthesized in high purity and good yields. The workup procedure of reaction is simple. The catalyst was easily separated from the reaction mixture with the assistance of an external magnetic field and reused for several runs without deterioration in catalytic activity. The core/shell nanoparticles were characterized by transmission electron microscopy, scanning electron microscope, powder X-ray diffraction, energy dispersive spectrometer, Fourier transform infrared spectroscopy and vibrating sample magnetometer.     

An efficient synthesis of 2-amino-4-aryl-6,7,8,9-tetrahydro-5H-benzo[7]annulene-1,3-dicarbonitriles in THF with DBU as catalyst

An efficient and convenient multicomponent reaction for preparation of 2-amino-4-aryl-6,7,8,9-tetrahydro-5H-benzo[7]annulene-1,3-dicarbonitrile derivatives, in THF, with DBU as catalyst is reported. These compounds are typical acceptor–donor–acceptor (A–D–A) systems comprising one electron donor and two electron acceptors with different important chemical properties. Excellent yields and the simplicity of the reaction procedure make this one of the most efficient methods for synthesis of these types of compound.     

TiO2ZrO2 composite: Synthesis,characterization and application as a facile,expeditious and recyclable catalyst for the synthesis of 2-aryl substituted benzoxazole derivatives

The activity of an efficient mesoporous TiO₂ZrO₂ composite catalyst for the synthesis of 2-aryl substituted benzoxazole derivatives using 2-aminophenol and substituted benzaldehydes/heterocyclic aldehydes at moderate temperature was studied. The catalyst was prepared by a co-precipitation method and characterized by X-ray diffraction, BET surface area and scanning electron microscopy. The effect of temperature, solvents and catalyst concentration on the synthesis of benzoxazole derivatives was systematically investigated. Short reaction times, green-reaction profiles, good to excellent yields, reliable cost efficiency, simple workup conditions and reusability of an eco-friendly catalyst are the noteworthy highlights of the reported method. The catalyst could be easily recovered and reused several times without any significant loss in the yield. The use of the present catalytic system to mediate the title chemical synthesis in a synthetic operation is important for the development of new atom-economic strategies and this is efficient in building complex structures from simple starting materials in an environmentally benign fashion.     

A Facile Procedure for Conjugate Addition of Amines to Electron Deficient Alkenes with Metal Oxide as Catalyst

A novel efficient procedure has been developed for the conjugate addition of amines to electron deficient alkenes. A series of metal oxides was synthesized for catalyzing the conjugate addition of amines and alkenes. After optimizing the reaction conditions, SrO was chosen as the most efficient catalyst for the reactions. The results show that the catalyst is very efficient for the conjugate addition of amines to electron deficient alkenes with the excellent yields in several minutes. Operational simplicity...     

纳米尺度NiLa2O4尖晶石催化NaBH4还原亚胺制仲胺

由溶胶-凝胶法制得的Ni-La化合物经热分解制备了纳米尺度NiLa2O4尖晶石，在750 oC焙烧后形成了结晶良好的尖晶石结构.采用差热分析、X射线衍射、透射电镜、扫描电镜和粒度分布分析等手段表征了该尖晶石的物理化学性质.结果表明，该纳米颗粒有规则的外形和确定的晶面，由平均粒径为40 nm的规整半球晶粒组成.精修的晶胞参数a=3.861205?和c=12.6793?.在NaBH4选择还原亚胺制相应仲胺的反应中，该新型纳米NiLa2O4尖晶石可用作高效多相催化剂，得到了较高的产物产率.所有反应可在室温和相对较短的时间内完成.在优化的反应条件下，均可得到带有不同芳基的，包括带有吸电子和供电子基团的仲胺.该催化剂回收简便，重复使用4次，其催化活性未见明显下降.     

Microwave‐Accelerated Pd‐Catalyzed Desulfitative Direct C2‐Arylation of Free (NH)‐Indoles with Arylsulfinic Acids

The rapid and efficient direct C2‐arylation of free (NH)‐indoles with arylsulfinic acids proceeded through a microwave‐accelerated palladium‐catalyzed desulfitation reaction. By using PdCl₂ as a catalyst, silver acetate as an oxidant, and H₂SO₄ as an additive, arylsulfinic acids with both electron‐donating and electron‐withdrawing groups underwent desulfitative coupling with an array of free (NH)‐indoles, thereby selectively providing C2‐arylindoles in good yields.     

Preparation of a novel,efficient, and recyclable magnetic catalyst,γ-Fe_2O_3@HAp-Ag nanoparticles,and a solvent- and halogen-free protocol for the synthesis of coumarin derivatives

In this protocol, Ag supported on the hydroxyapatite-core–shell magnetic γ-Fe_2O_3nanoparticles(γFe_2O_3@HAp-Ag NPs) as a novel, efficient, and magnetically recyclable catalyst is synthesized, and characterized by transmission electron microscopy(TEM), scanning electron microscopy(SEM), Fourier transform infrared spectroscopy(FT-IR), X-ray diffraction(XRD), and vibrating sample magnetometry(VSM). The use of the catalyst is described in the synthesis of coumarin derivatives by the Pechmann condensation of various phenols with β-ketoesters under solvent- and halogen-free conditions at 80℃.This novel and inexpensive method offers advantages, such as recyclability simple experimental protocol, short reaction time, minimal work-up procedure, and excellent yields of products, together with desirable, eco-friendly, green aspects by avoiding toxic elements and solvents, and ease of recovery from the reaction mixture using an external magnet.     

Efficient,Iron-Catalyzed Synthesis of 2-Mercaptobenzothiazole Through S-Arylation/Heterocyclization of 2-Haloaniline with Potassium Xanthate

A mild and practical method for the synthesis of 2-mercaptobenzothiazole has been developed by using iron as an efficient catalyst. The present tandem reaction process allows access to a wide range of 2-mercaptobenzothiazoles in good to excellent yields by the reaction of 2-haloaniline with potassium O-ethyl dithiocarbonate in the presence of FeF₃ as a catalyst and 2,2′-bis(diphenylphosphino)-1,1′-binaphthyl as a ligand under an atmosphere of argon.     

Synthesis of 1-amidoalkyl-2-naphthol derivatives using a magnetic nano-Fe3O4@SiO2@Hexamethylenetetramine-supported ionic liquid as a catalyst under solvent-free conditions

Hexamethylenetetramine-functionalized silica-coated nano-Fe₃O₄ particles (MNPs@Hexamethylenetetramine) were prepared as a reusable heterogeneous catalyst using a facile process. The catalyst was synthesized and characterized using infrared, X-ray diffraction, scanning electron microscopy, thermogravimetric analysis, and vibrating sample magnetometer. This magnetic nanocatalyst was employed as an efficient, reusable, and environmentally benign heterogeneous catalyst for the synthesis of amidoalkylnaphthol derivatives from a one-pot three-component condensation reaction of beta-naphthol, aldehydes, and amides in good to excellent yields, Moreover, this catalyst can be easily recovered by using a magnetic field and directly reused for at least seven runs without sign ificant loss of its activity.     

DABCO-catalyzed [2+2] cycloaddition reactions of allenoates and trifluoromethylketones: synthesis of 2-alkyleneoxetanes

DABCO was found to be an efficient catalyst for the formal [2+2] cycloaddition reaction of allenoates and trifluoromethylketones (Paterno-Buchi reaction) to give the corresponding 2-alkyleneoxetanes in good yields with good diastereoselectivities.     

Synthesis of benzimidazoles/benzothiazoles by using recyclable,magnetically separable nano-Fe<Subscript>2</Subscript>O<Subscript>3</Subscript> in aqueous medium

An efficient, simple, ecofriendly and cost-effective method has been developed for the synthesis of benzimidazole/benzothiazole derivatives by a two-component reaction, involving 1,2-diamino benzene/2-amino thiophenol and substituted aromatic aldehydes using recyclable nano-Fe₂O₃ catalyst (10 mol%) in water afforded with excellent yields (75–85%). The most important feature of this protocol is short reaction times, high yields, aqueous reaction medium, efficient recycling and high stability of the catalyst.     

Supramolecular synthesis of 3,4-dihydropyrimidine-2(1H)-one/thiones under neat conditions

An efficient solvent free method for the synthesis of various 3,4-dihydropyrimidin-2(1H)-one/thiones in excellent yields using sulfonatedβ-cyclodextrine as recyclable catalyst is described.Sulfonatedβ-cyclodextrine was found to be efficient,recyclable heterogeneous catalyst and showed rate enhancements,high yields and short reaction times in this transformation.     

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.     

Direct, regioselective synthesis of 2,2-dimethyl-2H-chromenes. Total syntheses of octandrenolone and precocenes I and II

Herein is reported an efficient method for the synthesis of 2,2-dimethyl-2H-chromenes in a single step from the corresponding phenol and 3-methyl-2-butenal via microwave irradiation in CDCl₃. This protocol features a mild reaction environment (neutral, no added catalyst) which yields regioselective formation of the chromene and displays tolerance toward acid- and base-sensitive protecting groups.     

SO4−2/SnO2–catalyzed cyclocondensation for the synthesis of fully functionalized pyridines

An efficient and promising synthetic approach to assemble skeletons of multifunctionalized pyridine derivatives in presence of recyclable heterogeneous sulfated tin oxide (STO) catalyst has been evolved. The STO catalyst was used as a promoter for the cyclocondensation process in ethanol at 70°C. Overall performance of this catalyst was attributed to the cooperative contribution of its Lewis and Brønsted-Lowry acidic sites. Nanosized STO catalyst was synthesized by using sol-gel process and characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), ¹H-NMR, and scanning electron microscopy (SEM). This catalyst tolerates most of the substrates, and protocol shows precious capabilities consist of high yields, operational simplicity, less reaction time, and eco-friendly conditions. The newly synthesized heterogeneous catalyst was easily separated and reused. All the reactions are carried out for subsequent cycles without significant loss of catalytic activity and with good proficiency.     

Immobilized Pd on a NHC functionalized metal–organic framework MIL-101(Cr): an efficient heterogeneous catalyst in Suzuki−Miyaura coupling reaction in water

A novel Pd−NHC functionalized metal–organic framework (MOF) based on MIL-101(Cr) was synthesized and used as an efficient heterogeneous catalyst in the C-C bond formation reactions. Using this heterogeneous Pd catalyst system, the Suzuki−Miyaura coupling reaction was accomplished well in water, and coupling products were obtained in good to excellent yields in short reaction time. The Pd−NHC−MIL-101(Cr) was characterized using some different techniques, including Fourier transform-infrared, X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy, inductively coupled plasma and elemental analysis. The microscopic techniques showed the discrete octahedron structure of MIL-101(Cr), which is also stable after chemical modification process to prepare the catalyst system. The TEM images of the catalyst showed the existence of palladium nanoparticles immobilized in the structure of the catalyst, while no reducing agent was used. It seems that the NHC groups and imidazolium moieties in the structure of the MOF can reduce Pd (II) to Pd (0) species. This modified MOF substrate can also prevent aggregation of Pd nanoparticles, resulting in high stability of them in organic transformation. The Pd−NHC−MIL-101(Cr) catalyst system could be simply extracted from the reaction mixture, providing an efficient synthetic method for the synthesis of biaryls derivatives using the aforementioned coupling reaction. The Pd−NHC−MIL-101(Cr) catalyst could be recycled in this organic reaction with almost consistent catalytic efficiency.     

The oxidation of aldehydes to acids with calcium hypochlorite [Ca(OCl)2]

Calcium hypochlorite is an efficient reagent for the oxidation of aldehydes to the corresponding acids. Reactions are carried out at ambient temperature in aqueous acetonitrile-acetic acid solution. Aliphatic aldehydes and aromatic aldehydes with electron withdrawing groups afford good to excellent yields. Nuclear chlorination is the preferred reaction in aromatic aldehydes with electron donating groups.