Highly efficient CuOx/OMS-2 catalyst for synthesis of phenoxathiin derivatives via intramolecular arylations of phenols with aryl halides

Phenoxathiin and its derivatives have attracted a great deal of interest due to their unique chemical and physical properties and their applications in fluorescent materials, antifungal activities and selective inhibitors. In the presence of copper supported on manganese oxide-based octahedral molecular sieves OMS-2 (CuO_x/OMS-2), the heterogeneously catalytic synthesis of phenoxathiinan derivatives via intramolecular arylations of phenols with aryl bromide or aryl chloride has been achieved. TEM and XRD have confirmed the CuO_x/OMS-2 catalyst has been successfully reused 8 times without a significant decrease in the yield, with simple filtration and washing as a means of separation.     

Highly efficient and reusable polystyrene‐supported copper(II) catalytic system for S‐arylation of potassium thiocyanate by aryl halides in water

An inexpensive, efficient and environmentally friendly copper(II) catalyst supported on polystyrene was successfully synthesized and used as a heterogeneous catalyst for S‐arylation of potassium thiocyanate by aryl halides. Also this catalyst could be recovered and reused several times without any noticeable decrease in its catalytic activity. Copyright © 2016 John Wiley & Sons, Ltd.     

An efficient and simple protocol for a PdCl2-ligandless and additive-free Suzuki coupling reaction of aryl bromides

A highly efficient, convenient, and environmentally friendly protocol was developed for the PdCl₂-catalyzed ligandless and additive-free Suzuki reaction of aryl bromides with arylboronic acids in water/ethanol.     

Efficient hydrosilylation of carbonyl compounds by 1,1,3,3-tetramethyldisiloxane catalyzed by Au/TiO2

1,1,3,3-Tetramethyldisiloxane (TMDS) is a highly reactive reducing reagent in the Au/TiO₂-catalyzed hydrosilylation of carbonyl compounds relative to monohydrosilanes. The reduction of aldehydes or ketones with TMDS can be performed on many occasions at ambient conditions within short reaction times and at low loading levels of gold, whereas typical monohydrosilanes require excess heating and prolonged time for completion. The product yields are excellent, while almost stoichiometric amounts of carbonyl compounds and TMDS can be used. It is postulated that the enhanced reactivity of TMDS is attributed to the formation of a gold dihydride intermediate. This intermediate is also supported by the fact that double hydrosilylation of carbonyl compounds by TMDS is a negligible pathway.     

A simple and efficient synthesis of 2-substituted benzothiazoles catalyzed by H_2O_2/HCl

A simple and efficient procedure for the synthesis of substituted benzothiazoles through condensation of 2-aminothiophenol with aromatic aldehydes in the presence of H_2O_2/HCl system in ethanol at room temperature is described.The target compounds have been characterized by ~1H NMR,~(13)C NMR,IR and MS.Short reaction time,easy and quick isolation of the products,and excellent yields are the main advantages of this procedure.     

Highly efficient C-H insertion reactions of hydrogen peroxide catalyzed by homogeneous and heterogeneous methyltrioxorhenium systems in ionic liquids

A convenient and efficient C-H insertion reaction of environment friendly H₂O₂ into representative hydrocarbon derivatives by homogeneous methyltrioxorhenium (MTO), heterogeneous poly(4-vinylpyridine)/methyltrioxorhenium (PVP/MTO) and microencapsulated polystyrene/methyltrioxorhenium (PS/MTO) systems in ionic liquids, is described. In some cases a higher activity was observed if compared with the same reaction in molecular solvents. The heterogeneous catalysts are stable systems under the reaction conditions and can be recycled for more transformations.     

Sonogashira reaction of aryl and heteroaryl halides with terminal alkynes catalyzed by a highly efficient and recyclable nanosized MCM-41 anchored palladium bipyridyl complex

A heterogeneous catalyst, nanosized MCM-41-Pd, was used to catalyze the Sonogashira coupling of aryl and heteroaryl halides with terminal alkynes in the presence of CuI and triphenylphosphine. The coupling products were obtained in high yields using low Pd loadings to 0.01 mol%, and the nanosized MCM-41-Pd catalyst was recovered by centrifugation of the reaction solution and re-used in further runs without significant loss of reactivity.     

A simple and efficient synthesis of 2-substituted benzothiazoles catalyzed by H_2O_2/HC1

A simple and efficient procedure for the synthesis of substituted benzothiazoles through condensation of 2-aminothiophenol with aromatic aldehydes in the presence of H₂O₂/HCl system in ethanol at room temperature is described. The target compounds have been characterized by ¹H NMR, ¹³C NMR, IR and MS. Short reaction time, easy and quick isolation of the products, and excellent yields are the main advantages of this procedure.     

Microwave assisted highly efficient one-pot multi-component synthesis of novel 2-(tetrasubstituted-1H-pyrrol-3-yl)-4H-chroman-4-ones catalyzed by heterogeneous reusable silica gel supported polyphosphoric acid (PPA/SiO2)

A solvent-free, eco-friendly and facile approach for the synthesis of highly functionalized tetrasubstituted pyrroles has been reported through one-pot four-component reaction of aldehyde, amine, nitroalkane and 1,3-diketone using silica gel supported polyphosphoric acid (PPA–SiO₂) under microwave condition. The reaction occured through the in situ formation of β-keto enamine and nitrostyrene analog following Michael addition and finally intramolecular annulation affording the products in good yields. The key features of the present method include clean reaction, mild conditions, low catalyst loading, straightforward, high to excellent yields, short reaction time, avoiding use of harmful metal catalyst and organic solvent, environmentally friendly compared to the existing methods, recovery and reusability of catalyst and easy workup procedure.     

Reductive carbonylation of aryl and heteroaryl iodides using Pd(acac)2/dppm as an efficient catalyst

Palladium catalyzed simple and efficient protocol for reductive carbonylation of aryl and heteroaryl compounds has been developed. The formylation of aryl and heteroaryl iodides takes place in the presence of Pd(acac)₂/dppm catalyst at 10 bar pressure of synthetic gas to give the desired aromatic and heteroaromatic aldehydes in good to excellent yields. Easy work-up, stability of the catalyst, low catalyst loading and less reaction time are the advantages of this method.     

The efficient one-pot synthesis of tetraalkyl substituted furans from symmetrical acetylenes,EtAlCl2, and carboxylic esters catalyzed by Cp2TiCl2

A new one-pot method for the synthesis of tetraalkyl substituted furans in 74–80% yields has been implemented via the reaction between symmetrical acetylenes, ethylaluminum dichloride, and carboxylic esters in the presence of metallic Mg as an acceptor of halide ions, catalyzed by bis(cyclopentadienyl)titanium dichloride. A mechanism for the reaction is proposed and discussed.     

多氟烯烃和炔烃的钯催化氢化

本文报道Pd/Al_2O_3(1%)催化剂催化氢化CF_3CCl=CClCF_3,CF_3CCI==CHCF_3和CF_3C=CCF_3等多氟烯烃和炔烃的结果。经1~H和(19)~F核磁共振、质谱、红外等分析,证明了用制备色谱分离后的氢化产物主要成份的结构。前二者的氢化产物中主要是CF_3CH_2CH_2CF_3和CF_3CH_2CHClCF_3的混合物,而CF_3C=CCF_3氢化后只生成CF_3CH_2CH_2CF_3。     

Chemically induced dynamic nuclear polarization and reaction of Et3Al with CCl4 catalyzed by Ni(acac)2

The influence of Ni(acac)₂ added in catalytic amounts on the chemically induced dynamic nuclear polarization (CIDNP) effects, the mechanism of interaction, and the products of reaction between Et₃Al and CCl₄ were studied. The radical intermediates were identified and the routes for their transformations were proposed. The thermal reaction of Et₃Al with CCl₄ occurs by a radical mechanism. However, in the presence of Ni(acac)₂, the reaction proceeds mainlyvia a nonradical route and gives large amounts of ethylene and ethane. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1580–1583, August, 1998.     

A simple and efficient synthesis of 3,4-dihydropyrimidin-2-(1H)-ones via Biginelli reaction catalyzed by nanomagnetic-supported sulfonic acid

Nanomagnetic-supported sulfonic acid is found to be a new, powerful, and reusable heterogeneous catalyst for the rapid synthesis of 3,4-dihydropyrimidin-2-(1H)-ones under conventional heating and microwave irradiation. This is the first example of combination of magnetic iron nanoparticles and microwave technique for the multicomponent reaction. The optical behaviors of the 3,4-dihydropyrimidin-2-(1H)-ones have been investigated by UV–vis spectroscopy.     

Highly efficient and regioselective allylic amination of allylic alcohols catalyzed by [Mo3PdS4] cluster

A highly efficient and regioselective allylation reaction of amines with allylic alcohols under mild conditions catalyzed by the cubane-type sulfido cluster [(Cp∗Mo)₃S₄Pd(dba)][PF₆] with H₃BO₃ as an additive has been developed. A variety of amines and allylic alcohols are investigated, and in the case of allylic alcohols bearing substituents at either α- or γ-position only linear allylic amination products are obtained.     

An environmentally benign room temperature aqueous homo‐ and copolymerization of styrene and methylmethacrylate catalyzed by [Cp2TiCl2]/NaBPh4

[Cp₂TiCl₂] has been found to be an effective precatalyst for room temperature aqueous homo‐ and copolymerization of methyl methacrylate and styrene in the presence of a cocatalyst, NaBPh₄ and an emulsifier, sodium n‐dodecyl sulfate. The polymers obtained are of high molecular weight with low molecular weight distribution. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 6496–6503, 2009     

An efficient and simple synthesis of α-amino phosphonates as ‘drug like’ molecules catalyzed by silica-supported perchloric acid (HClO4–SiO2)

An efficient and direct protocol is described for the preparation of α-amino phosphonates derivatives by employing a multi-component, one-pot condensation reaction of aldehyde, amine and trialkyl phosphite in the presence of silica-supported perchloric acid (3 mol%) under solvent-free conditions. The thermal solvent-free green procedure offers advantages such as shorter reaction time, simple work-up, high yield, recovery and reusability of catalyst.     

Highly efficient and chemoselective method for the thioacetalization of aldehydes and transthioacetalization of acetals and acylals catalyzed by H2SO4-silica under solvent-free conditions

Abstract  

Chemoselective and efficient thioacetalization of a variety of aldehydes was achieved in excellent yields at room temperature using 1,2-ethanedithiol in the presence of catalytic amounts of H₂SO₄-silica. Thioacetals were also prepared by transthioacetalization of acylals and acetals under similar conditions.     

Enantioselective [4+2] cycloaddition of ketenes and 9,10-phenanthrenequinone catalyzed by N-heterocyclic carbenes

Chiral N-heterocyclic carbenes were found to be efficient catalysts for the formal [4+2] cycloaddition reaction of alkyl(aryl)ketenes and 9,10-phenanthrenequinone to give the corresponding cycloadducts in good yields with high enantioselectivities.