Immobilized copper(II) on nitrogen‐rich polymer‐entrapped Fe3O4 nanoparticles: a highly loaded and magnetically recoverable catalyst for aqueous click chemistry

A heterogeneous magnetic copper catalyst was prepared via anchoring of copper sulfate onto multi‐layered poly(2‐dimethylaminoethyl acrylamide)‐coated magnetic nanoparticles and was characterized using various techniques. The catalyst was found to be active, effective and selective for one‐pot three‐component reaction of alkyl halide, sodium azide and alkyne, known as copper‐catalyzed click synthesis of 1,2,3‐triazoles. As little as 0.3 mol% of catalyst was found to be effective under the optimum conditions. The catalyst could also be recycled and reused up to seven times without significant loss of activity. Thermal stability, high loading level of copper on catalyst, broad diversity of alkyl/benzyl/allyl bromide/chloride and alkyl/aryl terminal alkynes without isolation of azide intermediate, and good to excellent yields of products make this procedure highly economical. Copyright © 2015 John Wiley & Sons, Ltd.     

A silica gel supported cobalt(Ⅱ) Schiff base complex as efficient and recyclable heterogeneous catalyst for the selective aerobic oxidation of alkyl aromatics

A silica gel supported cobalt(Ⅱ) Schiff base complex was synthesized and used for the oxidation of alkyl aromatics using molecular oxygen as an oxidant under atmosphere pressure.The catalyst shows a high conversion of alkyl aromatics and selectivity to benzylic ketones,and could be reused at least 5 times without significant loss of catalytic activity.     

An iron-containing ionic liquid as recyclable catalyst for aryl grignard cross-coupling of alkyl halides

[reaction: see text] The ionic liquid butylmethylimidazolium tetrachloroferrate (bmim-FeCl(4)) was found to be a very effective and completely air stable catalyst for the biphasic Grignard cross-coupling with primary and secondary alkyl halides bearing beta-hydrogens. After simply decanting the product in the ethereal layer, the ionic liquid catalyst was successfully recycled four times.     

Copper nanoparticles supported on polyaniline‐functionalized multiwall carbon nanotubes: An efficient and recyclable catalyst for synthesis of unsymmetric sulfides using potassium ethyl xanthogenate in water

A new and powerful polyaniline‐functionalized carbon nanotube‐supported copper(II) nanoparticle catalyst was successfully prepared and evaluated as a heterogeneous catalyst for the one‐pot synthesis of unsymmetric thioethers by coupling of aryl, alkyl and benzyl halides using potassium ethyl xanthogenate as source of sulfur in water. All of these reactions gave the desired products in good to excellent yields. The catalyst is available, air‐stable and can be reused several times without significant loss in its catalytic activity.     

Efficient One‐pot Synthesis of Alkyl 3‐(alkyl)‐4‐methyl‐2‐thioxo‐2,3‐dihydrothiazole‐5‐carboxylates in a Multi Component Reaction

A simple and efficient one‐pot synthesis of alkyl 2‐(alkyl)‐4‐methyl‐2‐thioxo‐2,3‐dihydrothiazole‐5‐carboxylates from the reaction of primary alkylamines and carbon disulfide in the presence of 2‐chloro‐1,3‐dicarbonyl compounds is described. This new protocol has several advantages such as lack of necessity of the catalyst, good yields, mild conditions and short times for reaction.     

One-step synthesis of reusable, polymer-supported tri-alkyl phosphine ligands. Application in Suzuki-Miyaura and alkoxycarbonylation reactions

A simple, efficient one-step route to polystyrene-supported trialkylphosphine ligands is reported. These polymer-supported alkyl phosphine ligands proved to be highly active for Suzuki-Miyaura reactions and in alkoxycarbonylation reactions. The palladium loaded polymer-supported catalysts can be recycled several times with only minimal loss of catalyst activity.     

无溶剂条件下煤基活性炭负载硫酸作为固体酸催化合成 14-烷基(芳基)-14H-二苯并[a,j]氧杂蒽类化合物

以自制的煤基活性炭负载硫酸为催化剂, β-萘酚、醛和脂肪醛为原料, 用一锅法成功合成了11个14-烷基(芳基)-14H-二苯并[a,j]氧杂蒽类化合物, 反应时间0.1～1 h, 收率71%～96%. 该方法不仅反应时间短, 产率高, 而且催化剂价廉易得, 对环境友好, 可重复利用5次, 活性没有明显降低, 并测得催化剂的酸值为3.06 mmol/g.     

A tricyclic aluminum alkoxide catalyst for aldehyde trimethylsilylcyanation

Trimethylsilylcyanation of aldehydes is efficiently accomplished with a low concentration of catalyst 1 under mild conditions in acetonitrile. This protocol tolerates a variety of electron-rich, neutral, and deficient aryl, heterocyclic, and alkyl aldehydes. At the end of the reaction, catalyst 1 precipitates from solution, allowing it to be recycled three times.     

Sonochemical Synthesis of 1,4‐Disubstituted 1,2,3‐Triazoles in Aqueous Medium

An ultrasound‐accelerated fast and efficient three‐component reaction for the regioselective synthesis of l,4‐disubstituted 1,2,3‐triazoles using different alkyl and allyl halides, terminal alkynes, and sodium azide in water at room temperature has been developed using CuI as catalyst. Ultrasonication dramatically decreases the reaction times.     

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.     

Effect of Alkyl Aluminums on Ethylene Polymerization Reactions with a Cr‐V Bimetallic Catalyst

The effect of introducing various types of alkyl aluminums directly into the catalyst and/or in the polymerization process as cocatalyst on the efficiency of a Cr‐V bimetallic catalyst for ethylene polymerization is systematically investigated. Results indicate that polymerization activity, kinetic behavior, and polymer properties of the Cr‐V catalyst are strongly affected by using alkyl aluminums in different stages of polymerization, due to the different responses and sensitivities of the two metal centers to alkyl aluminum. When employed as cocatalyst, triisobutyl aluminum gives high activity and polyethylene with relatively low molecular weight, while diethylaluminum chloride cocatalyzes the production of ultra‐high molecular weight polyethylene but with very low activity. On the other hand, the pre‐reduction of the bimetallic catalyst by alkyl aluminums has a marked promotion effect on catalyst efficiency. It is suggested that the addition of alkyl aluminum to the catalyst and to the reactor as cocatalyst are more or less equivalent in their effects on the improvement of polymerization activity, but they behave in different ways to affect polymer properties.     

Manganese‐Containing Periodic Mesoporous Organosilica with Ionic‐Liquid Framework (Mn@PMO‐IL): A Powerful,Durable, and Reusable Nanocatalyst for the Biginelli Reaction

The catalytic application of a novel manganese‐containing periodic mesoporous organosilica with ionic‐liquid framework (Mn@PMO‐IL) in the Biginelli reaction was investigated. First, the Mn@PMO‐IL nanocatalyst was prepared and characterized by TEM, SEM, X‐ray photoelectron spectroscopy, and nitrogen‐sorption analysis. The catalyst was then used in the one‐pot Biginelli condensation of various aldehydes with urea and alkyl acetoacetates under solvent‐free conditions. The corresponding dihydropyrimidone products were obtained in high to excellent yields and selectivities at short reaction times. Moreover, the catalyst was recovered and successfully reused many times with no notable decrease in activity and selectivity.     

Ti(IV)-based catalytic membranes for efficient and selective oxidation of secondary amines

The incorporation of homogenous Ti(IV)/trialkanolamine catalyst in polymeric membranes provided new polymeric catalytic Ti(IV)-based membranes, stable and efficient as heterogeneous catalysts for chemoselective oxidations of secondary amines to nitrones by alkyl hydroperoxides. Polyvinylidene fluoride (PVDF)-based catalytic membranes gave the best results affording products in short reaction times, high yields and selectivity using as little as 1% of catalyst, comparable with the performances of the corresponding homogeneous system. PVDF-Ti membrane could be recycled up to five runs with no loss of activity.     

H2‐Acceptorless Dehydrogenative Boration and Transfer Boration of Alkenes Enabled by Zirconium Catalyst

The first example of an efficient and direct dehydrogenative boration of alkenes for vinyl boronate ester synthesis was achieved using a zirconium catalyst. Our methodology avoids using precious transition metals, additional hydrogen acceptors, high temperatures, and long reaction times, which were required to overcome the reducing ability of borane, to give alkyl boronate esters. Detailed mechanistic studies revealed a reversible reaction pathway and further suggested applying the zirconium complex as a “shuttle catalyst” for transfer boration, which thus sidesteps the use of relatively sensitive borane.     

Mesoporous aluminosilicate-catalyzed allylation of carbonyl compounds and acetals

A mesoporous aluminosilicate (Al-MCM-41) was found to be an effective heterogeneous catalyst for the reaction of both carbonyl compounds and acetals with allylsilanes to afford the corresponding homoallyl silyl ethers and homoallyl alkyl ethers, respectively. Both the mesoporous structure and the presence of aluminum moiety were indispensable for the high catalytic activity of Al-MCM-41. Moreover, Al-MCM-41 could catalyze the reaction of acetals chemoselectively in the presence of the corresponding carbonyl compounds. The solid acid catalyst Al-MCM-41 could be recovered easily by filtration and could be reused three times without a significant loss of catalytic activity.     

The first applications of carbene ligands in cross-couplings of alkyl electrophiles: sonogashira reactions of unactivated alkyl bromides and iodides

A Pd/N-heterocyclic carbene-based catalyst achieves the Sonogashira coupling of an array of functionalized, beta-hydrogen-containing alkyl bromides and iodides under mild conditions. By furnishing the first example of a nonphosphine-based palladium catalyst for cross-coupling unactivated alkyl electrophiles, this study provides an impetus for future efforts at catalyst development that extend beyond phosphine ligands.     

Functionalized graphene oxide supported copper (I) complex as effective and recyclable nanocatalyst for one‐pot three component synthesis of 1,2,3‐triazoles

Efficient, one pot three‐component reaction of alkyl halides, sodium azide with terminal alkynes can be catalyzed by functionalized graphene oxide with copper(I) under thermal conditions. A series of 1,4‐disubstituted 1,2,3‐triazoles were obtained by this one‐pot strategy. The catalyst was prepared and characterized by Fourier transform infrared spectroscopy (FT‐IR), X‐ray diffraction (XRD), emission scanning electron microscopy (FE‐SEM) and energy dispersive X‐ray (EDX). The catalyst can be reused at least five times without significant deactivation.     

A Binary Silicon-Centered Organoboron Catalyst with Superior Performance to That of Its Bifunctional Analogue

This work reported that a silicon-centered alkyl borane/ammonium salt binary (two-component) catalyst exhibits much higher activity than its bifunctional analogue (one-component) for the ring-opening polymerization of propylene oxide, showing 7.3 times the activity of its bifunctional analogue at a low catalyst loading of 0.01 mol %, and even 15.3 times the activity at an extremely low loading of 0.002 mol %. By using ¹⁹F NMR spectroscopy, control experiments, and theoretical calculation we discovered that the central silicon atom displays appropriate electron density and a larger intramolecular cavity, which is useful to co-activate the monomer and to deliver propagating chains, thus leading to a better intramolecular synergic effect than its bifunctional analogue. A unique two-pathway initiation mode was proposed to explain the unusual high activity of the binary catalytic system. This study breaks the traditional impression of the binary Lewis acid/nucleophilic catalyst with poor activity because of the increase in entropy.     

水杨亚胺基钯催化聚合丙烯的密度泛函理论研究

Grubbs水杨亚胺基镍/钯催化剂是一类新型含氮、氧配位杂原子的中性单组分 烯烃聚合催化剂。以不带取代基的水杨亚胺钯为模型催化剂，采用密度泛函理论 在B2LYP/LANL2DZ水平上对其催化聚合丙烯的链增长机理进行了研究。与催化剂配 位原子氮的对位进攻相比，丙烯从氧的对位进攻的复合能大、插入能低。当烷基链 在配位原子O的对位时1，2-插入速率低于2，1-插入；当烷基链在配位原子N对位时 ，1，2-插入速率高于2，1-插生产方式。能量量低的插入路径是烷基链在N对位是 的1，2-插入。2，1-插入路径中的γ-氢桥键烷基配合物能异构化得三个β-氢桥键 的烷基配合物，空间位阻最小的最稳定。1，2-插往前只生成一个β-氢桥键烷基配 合物。与氮原子对位的配合物相比，所有在配位原子氧对位的β-氢桥键的烷基配 合物都是更稳定的配合物构型。     

Chemoselectivity in the Cu-catalyzed O-arylation of phenols and aliphatic alcohols

An orthogonal set of Cu-catalysts for the selective mono-arylation of alkyl aryl diols using aryl iodides is presented. Picolinic acid ligated copper catalyst provided phenol O-arylation only, while alkyl aryl ethers are generated by ligand-free copper catalyst in the presence of 2 equivalents NaOt-Bu.