Glycerol mediated synthesis of 5-substituted 1H-tetrazole under catalyst free conditions

We have developed simple,cost effective and environmentally benign protocol for the synthesis of 5-substituted 1H-tetrazoles via[2,3]cycloaddition reaction from organic nitriles and sodium azide in glycerol under catalyst free condition.The corresponding 5-substituted 1H-tetrazoles were obtained with good to excellent yields(68-95%).     

Boehmite@SiO2@ Tris (hydroxymethyl)aminomethane-Cu(I): a novel,highly efficient and reusable nanocatalyst for the C-C bond formation and the synthesis of 5-substituted 1H-tetrazoles in green media

In this work, a versatile protocol was introduced for the preparation of a new Cu(I) supported complex on Silica supported boehmite nanoparticles (Boehmite@SiO₂@Tris-Cu(I)). The structure of the catalyst was comprehensively characterized using Fourier transform infrared spectroscopy (FT-IR), X-Ray Diffractometer (XRD), energy-dispersive X-ray spectroscopy (EDS), inductively coupled plasma atomic emission spectroscopy (ICP), X-ray mapping, thermogravimetric analysis (TGA) and scanning electron microscopy (SEM) techniques. The catalytic activity of this catalyst was studied in the Suzuki cross-coupling reaction and synthesis of 5-substituted 1H-tetrazole derivatives in ethanol and PEG-400 respectively as green solvents. In this sense, simple preparation of the catalyst from the commercially available materials, high catalytic activity, simple operation, short reaction times, high yields and use of green solvent are some advantages of this protocol. Finally, it is worth mentioning that this nanocatalyst was easily recovered, and reused for several times without significant loss of its catalytic efficiency. In addition, stability of the catalyst after recycling was confirmed by FT-IR technique.     

1,3-Dibromo-5,5-dimethylhydantoin(DBH)/kaolin:An efficient reagent system for the synthesis of 14-aryl-14H-dibenzo[a,j]xanthenes under solvent-free conditions

1,3-Dibromo-5,5-dimethylhydantoin,has been used as an efficient catalyst for the synthesis of 14-aryl-14H-dibenzo[a,j]xanthenes in the presence of kaolin.All reactions are performed in the absence of solvent in relatively short reaction times in good to high yields.     

Diisopropylethylammonium acetate (DIPEAc): An efficient and recyclable catalyst for the rapid synthesis of 5-substituted-1H-tetrazoles

A simple and efficient protocol developed for the synthesis of 5-substituted 1H-tetrazole derivatives through [2+3] cycloaddition reaction between benzonitriles and sodium azide using diisopropylethylammonium acetate as a recyclable reaction medium is described. The reactions proceed well at 80?°C and provide the corresponding tetrazoles in good to excellent yields (up to 94% yield). Developed method has notable advantages, such as simple and mild conditions, easy workup, reusability with consistent catalytic activity, and safer alternative to hazardous, corrosive conventional Lewis acid catalysts.     

Iodine-Catalyzed,Efficient, One-Pot Protocol for the Conversion of Araldehydes into 5-Aryl-1H-tetrazoles

An easy access to various 5-aryl-1H-tetrazoles by a one-pot direct conversion of aldehydes to tetrazoles without the isolation of the intermediate nitriles using commercially available iodine as a catalyst is described. The protocol offers advantages in terms of good yields, mild reaction conditions, short reaction times, and use of readily available environmentally compatible catalyst.     

Solvent-free preparation of arylaminotetrazole derivatives using aluminum(Ⅲ) hydrogensulfate as an effective catalyst

<正>An efficient and simple method for the preparation of 5-arylamino-1H-tetrazole and 1-aryl-5-amino-1H-tetrazole derivatives is reported using aluminum(Ⅲ) hydrogensulfate(Al(HSO_4)_3) as an effective heterogeneous catalyst from secondary arylcyanamides. Generally,when the substitution in arylcyanamide is strongly electron-withdrawing the position of equilibrium would shift toward the isomer of 1-aryl-5-amino-1H-tetrazole(B) and as the electron-donating of substituent increased,the position of equilibrium is shifted toward the isomer of 5-arylamino-1H-tetrazole(A).The present methodology offers several advantages,such as excellent yields,short reaction times,easy work-up and greener conditions.     

水介质中1,6-二氧-5-氧代-1,4,5,6-四氢化菲衍生物的三组分一锅合成

水介质中在氯化三乙基苄基铵(TEBA)催化下, 芳醛与丙二腈和4-羟基香豆素三组分一锅反应合成了2-氨基-4-芳基-3-氰基-1,6-二氧-5-氧代-1,4,5,6-四氢化菲, 该反应具有产率高、污染少、操作简单、环境友好等优点.     

A convenient synthesis of 1,5-diarylpyrazoles from Baylis-Hillman adducts using HY-zeolite

<正>A facile and convenient protocol was developed for the synthesis of 1,5-diarylpyrazoles using Baylis-Hillman adducts in the presence of HY-zeolite as an efficient recyclable heterogeneous catalyst in reasonable reaction times(1.5-2.5 h) and high yields (78-90%).     

NbCl5 as an Efficient Catalyst for Chemoselective Synthesis of 1,1-Diacetates Under Solvent-Free Conditions

A mild and efficient method for the chemoselective preparation of 1,1-diacetates catalyzed by NbCl₅(5 mmol%) under solvent-free conditions has been developed. The yields are in the range of 93–98%. This protocol offered several advantages, including low catalyst loading, good yields, short reaction times, and environmentally friendliness.     

Copper coordinated-poly(α-amino acid) decorated on magnetite graphene oxide as an efficient heterogeneous magnetically recoverable catalyst for the selective synthesis of 5- and 1-substituted tetrazoles from various sources: A comparative study

In this work, poly(α-amino acid)-Cu(II) complex immobilized on magnetite graphene oxide (GO/Fe₃O₄@PAA-Cu-complex) was prepared via a multistep synthesis and employed as an efficient, heterogeneous, magnetically recyclable nanocatalyst for one-pot, three component synthesis of 5- and 1-substituted tetrazoles using different substrates including benzaldehydes, benzonitriles, and anilines in mild conditions. The different approaches were mechanically investigated and compared. The catalyst was fully characterized by Fourier transform infrared (FTIR), thermogravimetric analysis (TGA), X-ray diffraction (XRD), vibrating sample magnetometer (VSM), energy dispersive X-ray spectroscopy (EDX), inductively coupled plasma (ICP), FE-SEM and TEM analyses. The magnetic nanocatalyst could be readily separated from the reaction mixture by an external magnet and reused for several times without significant loss of catalytic activity. Also, the spectroscopic analysis revealed the stability and durability of the catalyst. Finally, the chemoselectivity of the method was investigated by the various combinations of aldehyde, nitrile, and oxime.     

New eco-friendly procedure for the synthesis of 4-arylmethylene-isoxazol-5(4H)-ones catalyzed by pyridinium p-toluenesulfonate (PPTS) in aqueous medium

In this work we describe a new, highly efficient method for the synthesis of 3-methyl-4-arylmethylidene-isoxazol-5(4H)-one derivatives by a three-component reaction between aromatic aldehydes, ethyl acetoacetate, and hydroxylamine hydrochloride under the influence by PPTS as a low-toxicity, inexpensive, commercially available and easy to handle catalyst. The advantages of this procedure are good yields, short reaction times, simplicity of implementation, and respect of the environment.     

Efficient synthesis of novel 9H-xanthen-9-yl derivatives of bidentate heterocyclic nucleophiles by Fe（HSO4）3 as a catalyst

We have demonstrated the direct substitution of 9H-xanthen-9-ol with different nucleophilic reagents such as thiazoles, triazoles,tetrazoles,hydrazines and hydrazinecarboxamides in good to high yields.This reaction catalyzed by ferric hydrogensulfate as a heterogeneous acid catalyst in ethanol through S_N1 type reaction of pyrylium with a nucleophilic reagent afforded the heterocycle- and aromatic-N-substituted xanthene derivatives as simple marked molecules in short reaction times.     

One‐pot synthesis of 1‐ and 5‐substituted 1H‐tetrazoles using 1,4‐dihydroxyanthraquinone–copper(II) supported on superparamagnetic Fe3O4@SiO2 magnetic porous nanospheres as a recyclable catalyst

An effective one‐pot, convenient process for the synthesis of 1‐ and 5‐substituted 1H‐tetrazoles from nitriles and amines is described using1,4‐dihydroxyanthraquinone–copper(II) supported on Fe₃O₄@SiO₂ magnetic porous nanospheres as a novel recyclable catalyst. The application of this catalyst allows the synthesis of a variety of tetrazoles in good to excellent yields. The preparation of the magnetic nanocatalyst with core–shell structure is presented by using nano‐Fe₃O₄ as the core, tetraethoxysilane as the silica source and poly(vinyl alcohol) as the surfactant, and then Fe₃O₄@SiO₂ was coated with 1,4‐dihydroxyanthraquinone–copper(II) nanoparticles. The new catalyst was characterized using Fourier transform infrared spectroscopy, X‐ray diffraction, transmission electron microscopy, field emission scanning electron microscopy, dynamic light scattering, thermogravimetric analysis, vibration sample magnetometry, X‐ray photoelectron spectroscopy, nitrogen adsorption–desorption isotherm analysis and inductively coupled plasma analysis. This new procedure offers several advantages such as short reaction times, excellent yields, operational simplicity, practicability and applicability to various substrates and absence of any tedious workup or purification. In addition, the excellent catalytic performance, thermal stability and separation of the catalyst make it a good heterogeneous system and a useful alternative to other heterogeneous catalysts. Also, the catalyst could be magnetically separated and reused six times without significant loss of catalytic activity. Copyright © 2016 John Wiley & Sons, Ltd.     

The First Recyclable,Nanocrystalline CdS Thin Film Mediated Eco‐benign Synthesis Of Hantzsch 1, 4 Dihyropyridines, 1, 8‐Dioxodecahydroacridine and Polyhydroquinolines derivatives

In the present study, we report a recyclable, nanocrystalline CdS thin film mediated efficient one‐pot, three component synthesis of Hantzsch 1, 4 Dihydropyridine in good yields. The catalyst is also effective for the efficient synthesis of Polyhydroquinoline and 1, 8‐dioxodecahydroacridine derivatives in good to excellent yields. The CdS thin film catalyst was prepared by chemical bath deposition (CBD) technique. The cadmium sulphide thin film was characterized by powder XRD and FT‐IR studies. The average crystallite size (D) was calculated from powder XRD by using Scherrer formula and SEM analysis. The elemental composition of the CdS thin film was established by EDS analysis. The effect of temperature, substituent's, catalyst loading and mole ratio on the reaction was also studied. All the products were thoroughly characterized by ¹H‐NMR, ¹³C‐NMR, FT‐IR, Mass spectral and CHN analysis. A plausible mechanism for the CdS thin film catalyzed synthesis of 1, 4 DHP's is proposed. The heterogeneous catalyst could be easily recovered from the reaction mixture and successively reused at least five times without loss of activity.     

Nano-sulfated zirconia as an efficient, recyclable and environmentally benign catalyst for one-pot three component synthesis of amidoalkyl naphthols

One pot synthesis of amidoalkyl naphthols by reaction of aromatic aldehydes,2-naphthol and amide/urea using nano-sulfated zirconia as a catalyst is reported.The reaction was carried out under solvent-free conditions.The method gave good yields of amidoalkyl naphthols in short reaction time.The catalyst is recycled for five consecutive times without loss of activity.     

Eco-friendly synthesis of benzimidazole derivatives using solid acid scolecite catalyst

<正>A series of benzimidazole derivatives were synthesized expeditiously in good yields by condensation of 1,2-diaminobenzene and aromatic aldehydes in the presence of modified scolecite catalyst.The world wide availability,easy handling and reusability of catalyst,higher yields and shorter reaction times are the advantages of the present method.     

Hafnium(Ⅳ) bis(perfluorooctanesulfonyl)imide complex catalyzed direct amidomethylation for the synthesis of 1-(arylamido)-methyl-2-naphthols in fluorous medium

Hafnium(Ⅳ) bis(perfluorooctanesulfonyl)imide complex is found to be an efficient catalyst for the multicomponent condensation ofβ-naphthol,aromatic aldehydes and urea or amides in perfluorodecalin to afford the corresponding substituted amidomethyl naphthols in good yields.The remarkable features of this new procedure are high yields,shorter reaction times, reusability of catalyst and simple work-up procedures.     

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.     

羽毛角蛋白稳定的钯纳米颗粒催化Suzuki偶联反应

采在温和条件下羽毛角蛋白负载的Pd纳米颗粒可高效催化水中溴代芳烃与苯硼酸的偶联反应,且具有官能团的广泛适用性,生成的联苯类化合物可在反应液中沉淀出来,具有很好的产率和纯度.催化剂通过简单过滤可重复使用7次.     

P-Dodecylbenzenesulfonic acid(DBSA),a Brфnsted acid-surfactant catalyst for Biginelli reaction in water and under solvent free conditions

We report herein the use of p-dodecylbenzenesulfonic acid(DBSA) as a catalyst for a one-pot Biginelli reaction to afford 3,4- dihydropyrimidinone derivatives in good to excellent yields.This reaction proceeds efficiently in water and under solvent free conditions.Comparisons of results indicate that although the yields are high and comparable for both methods,the reaction times are considerably shorter under solvent free conditions.