Ecofriendly and efficient procedure for hetero-Michael addition reactions with an acidic ionic liquid as catalyst and reaction medium

Abstract  

1-Methylimidazolium trifluoroacetate ([Hmim]TFA) is reported as a cost-effective catalyst for a simple and environmentally benign hetero-Michael reaction. [Hmim]TFA works both as reaction medium and catalyst. The reaction is applicable to various aromatic sulfur and nitrogen nucleophiles. This method has advantages such as high yields, short reaction time, and simple workup. The catalyst could be recycled 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。     

One-Pot Synthesis of Dihydropyrimidinones/Thiones Catalyzed by White Marble a Metamorphic Rock: an Efficient and Reusable Catalyst for the Biginelli Reaction

In this work, we report a simple, efficient and green protocol for the synthesis of dihydropyrimidinones/thiones (products of Biginelli reaction) by the use of white marble as an effective heterogeneous catalyst. Short reaction times, high product yields, simple processing procedure and reusability of the catalyst are the superior characteristics of this protocol.     

Solvent-free synthesis of dihydropyrimidinones catalyzed by alumina sulfuric acid at room temperature

A simple, efficient and practical procedure for the Biginelli reaction using alumina sulfuric acid (ASA) as a novel acid catalyst is described under solvent-free conditions. The catalyst exhibited remarkable reactivity at room temperature. The method offers several advantages including high yields, environmentally friendly procedure, short reaction times and simple work up procedure.     

活性炭负载壳聚糖催化室温无溶剂Knoevenagel缩合反应

通过活性炭(AC)负载壳聚糖(CS)的方法,制备了负载型的"壳聚糖/活性炭"催化剂(CS/AC)。利用FT-IR、XRD、TG-DTG、SEM、BET、元素分析等方法对催化剂进行表征,并系统研究了该催化剂在Knoevenagel缩合反应中的催化性能。结果表明,催化剂具有较好的活性,在室温无溶剂条件下,可以催化一系列芳香醛化合物与活泼亚甲基化合物进行缩合反应,产率均在80%以上;且反应体系放大100倍时,仍然保持较高的催化效率;此外,该催化剂具有较好稳定性,重复使用8次后,仍然保持较高的催化活性。     

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.     

Rapid and efficient one-pot synthesis of octahydroquinazolinone derivatives using lanthanum oxide under solvent-free condition

A simple, efficient and cost-effective method for the synthesis of octahydroquinazolinone derivatives using dimedone, urea/thiourea and aromatic aldehydes using lanthanum oxide as a catalyst under solvent free condition in microwave irradiation is reported. The present method does not involve any hazardous organic solvents. This catalyst has promising features for the reaction response such as the shortest reaction time, excellent product yields, simple work-up procedure and purification of products by non-chromatographic methods.     

Boehmite@tryptophan‐Pd nanoparticles: A new catalyst for C–C bond formation

A boehmite@tryptophan‐Pd nanoparticulate catalyst was prepared by a simple, fast and convenient route. The nanomaterial was characterized using various techniques and employed as a thermally stable catalyst for Heck, Stille and Suzuki cross‐coupling reactions. Optimized conditions for these reactions are described. The catalyst could be isolated, post‐reaction, by simple filtration and recycled for several consecutive cycles without a notable change in its activity.     

Xanthan Sulfuric Acid: An Efficient,Biosupported, and Recyclable Solid Acid Catalyst for the Synthesis of 4,4′-(Arylmethylene)bis(1H-pyrazol-5-ols)

A simple and efficient method has been developed for the synthesis of 4,4′-(arylmethylene)bis(1H-pyrazol-5-ols) by the condensation reaction between substituted aldehydes, and 1-phenyl-3-methylpyrazol-5-one in the presence of xanthan sulfuric acid (XSA) as a solid acid catalyst. This method is simple and cost-effective with short reaction times. Yields are excellent with high purity, and the catalyst could be easily recycled.     

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.     

Copper(II) acetate-catalyzed one-pot conversion of aldehydes into primary amides through a Beckmann-type rearrangement

Copper(II) acetate is a versatile catalyst for the direct transformation of any type of aldehydes into primary amides by stoichiometric reaction with hydroxylamine in water. The catalyst could be recovered 10 times without losing its activity, just by a simple organic layer extraction of the product. The catalyst and the protocol avoid the use of any type of expensive and difficult to handle organic ligand, as well as bases, showing excellent yields, under mild reaction conditions. The great purity of the crude product permits its purification by a simple recrystallization process. The whole protocol fulfils the principle of green chemistry and sustainability, minimizing the use of organic solvents and any type of wastes.     

Silica supported sodium hydrogen sulfate(NaHSO4/SiO2): A mild and efficient reusable catalyst for the synthesis of aryl-14-H-dibenzo[a,j]xanthenes under solvent-free conditions

A simple and efficient procedure for the preparation of aryl-14-H-dibenzo[a,j]xanthenes by a one-pot condensation reaction of 2-naphthol and aryl aldehydes,in the presence of silica supported sodium hydrogen sulfate(NaHSO_4/SiO_2)as a catalyst and in the absence of solvent has been developed.The present method offers several advantages such as excellent yields,short reaction time (10-30 min),mild condition,simple work-up,and the use of a cheap and environmentally friendly catalyst with remarkable reusability.     

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.     

Rapid,efficient and solvent-free synthesis of (un)symmetrical xanthenes catalyzed by recyclable sulfated polyborate

The present study describes a rapid, simple and straightforward approach to the synthesis of 1,8-dioxo-octahydroxanthenes, 14-phenyl-14H-dibenzo[a,j]xanthene and tetrahydrobenzoxanthene-11-ones under solvent-free conditions using sulfated polyborate as a highly efficient catalyst. The procedure offers several advantages including cleaner reaction profile, mild reaction condition, economic, recyclable and environmentally benign catalyst, high yields, simple experimental and workup procedures. While non-extractive work up/purification, along with reusability of catalyst make this method economically affordable for large scale.     

全氟辛基磺酸催化液态烯烃Friedel-Crafts反应的研究

烯烃的Friedel-Crafts烷基化反应(以下简称F-C烷基化反应)一般采用金属卤化物和浓硫酸作催化剂,但两种情况下的后处理都比较复杂,要消耗大量溶剂,催化剂只能一次性使用。近年来,由于苯乙烯与二甲苯反应产物为具有多种工业用途的材料"PXE",国内外相继报道使用不同的催化剂来改进该反应,这些反应各有优点,但均未提及机理和与之竞     

Efficient Domino Strategy for the Synthesis of Substituted Bipyrazole Derivatives

An efficient domino strategy for the synthesis of bipyrazole derivatives has been established successfully using Y(OTf)₃ as catalyst. This new reaction allows direct formation of highly functionalized bipyrazole derivatives with a wide diversity in substituents in a one‐pot manner. The present synthesis shows attractive characteristics, such as the use of water as reaction media, simple one‐pot operation, highly efficient catalyst, and mild reaction conditions.     

Convenient One‐Pot Heterogeneous Catalytic Method for the Preparation of 3,4‐Dihydropyrimidin‐2(1H)‐ones

A new, simple, environmentally friendly synthesis of dihydropyrimidinones from aromatic and aliphatic aldehydes, ethyl acetoacetate, and urea or thiourea using a small‐pore‐size zeolite as catalyst is described. Compared with the classical Biginelli reaction conditions, this method has the advantage of high yield, shorter reaction time, and recyclable and reusable catalyst.     

A heterogeneous and reusable nanopolymer-supported palladium catalyst for the copper- and phosphine-free Sonogashira coupling reaction under aerobic conditions in water

We report here the synthesis of a nanopolymer-supported palladium(II) complex catalyst, [PS-tet-Pd(II)] using a simple protocol. The catalyst was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), FT-IR, and energy dispersive X-ray spectroscopy (EDS). PS-tet-Pd(II) proves to be a useful heterogeneous catalyst in the copper- and phosphine-free Sonogashira coupling reaction in water. The catalyst can be recovered from the reaction mixture by simple filtration and reused several times without any significant loss of catalytic activity.     

Fluoroboric Acid Adsorbed on Silica-Gel–Catalyzed Synthesis of 14-Aryl-14H-dibenzo[a,j]xanthene Derivatives

A simple and efficient procedure has been developed for the preparation of 14-aryl-14H-dibenzo[a,j]xanthene derivatives using fluoroboric acid adsorbed on silica gel as a heterogeneous catalyst. The methodology involves the one-pot condensation reaction of β-naphthol and aryl aldehydes under solvent-free conventional heating conditions. The present approach offers several advantages such as shorter reaction times, simple work-up, excellent yields, low cost, and mild reaction conditions. The catalyst is easily recoverable and reusable without loss of its catalytic activity.     

Montmorillonite as a Heterogeneous Catalyst in the Efficient,Mild and One Pot Synthesis of Schiff Bases under Solvent‐Free Conditions

A mild and efficient method has been reported for preparation of Schiff base ligands through condensation reaction of various aromatic aldehydes and ketones with different aromatic amines in the presence of montmorillonite as a heterogeneous catalyst under solvent free conditions. The advantages of this friendly, economically, environmentally and mild method are such as; simplicity of the reaction procedure, reusability of catalyst, simple work‐up, high product yields and very short reaction times.