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.     

Synthesis of 5-substituted 1H-tetrazoles and oxidation of sulfides by using boehmite nanoparticles/nickel-curcumin as a robust and extremely efficient green nanocatalyst

Nickel-anchored curcumin-functionalized boehmite nanoparticles (BNPs@Cur-Ni) as a robust and versatile nanocatalyst was synthesized and well-characterized by using Fourier transform infrared (FT-IR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), X-ray mapping, thermogravimetric analysis (TGA), differential thermal analysis (DTA), Brunauer–Emmett–Teller (BET), X-ray diffraction (XRD), and inductively coupled plasma optical emission spectroscopy (ICP-OES). The synthesis of 5-substituted 1H-tetrazoles and the oxidation of sulfides were conducted by BNPs@Cur-Ni with excellent turnover number (TON) and turnover frequency (TOF) outcomes. Also, the catalyst was reused for several sequential runs without Ni leaching or decreasing in reaction yield. Utilizing the curcumin and boehmite with a natural source as well as poly(ethylene glycol) (PEG) as a solvent in this simple protocol can be based on green chemistry rules.     

New routes for the synthesis of 3- and 5-substituted 2(1H)-pyrazinones

Various 3-(hetero)aryl, 3-alkyl and 3-alkenyl-2(1H)-pyrazinones were prepared by applying the Suzuki and Heck reaction methodology to 3,5-dichloro-2(1H)-pyrazinones. Furthermore, following hydrogenolysis of the 5-chloro substituent and regioselective 5-bromination, this palladium-catalysed cross-coupling approach could be extended to the synthesis of the analogous 5-substituted 2(1H)-pyrazinones.     

Merrifield resin supported phenanthroline-Cu(I): a highly efficient and recyclable catalyst for the synthesis of 2-aminobenzothiazoles via the reaction of 2-haloanilines with isothiocyanates

A novel Merrifield resin supported phenanthroline-Cu(I) complex has been developed and used as a highly efficient and recyclable catalyst in the reaction of 2-halobenzenamines with isothiocyanates for the synthesis of 2-aminobenzothiazoles. The reactions were applicable to a variety of 2-halobenzenamines and isothiocyanates, and generated the corresponding 2-aminobenzothiazoles in good yields under mild reaction conditions. Moreover, the catalyst was quantitatively recovered from the reaction mixture by a simple filtration and reused for ten cycles with almost consistent activity.     

N-Sulfonic acid poly(4-vinylpyridinium) chloride as a highly effcient and reusable catalyst for the Biginelli reaction简

A mild, simple and efficient procedure for the preparation of 3,4-dihydropyrimidin-2（1H）-ones and -thiones is described using N-sulfonic acid poly（4-vinylpyridinium） chloride （NSPVPC） as a heterogeneous and efficient catalyst under solvent-free conditions. Simple methodologies, easy work-up procedure, easy preparation of the catalyst, excellent yields and very short reaction times are among the other advantages of this work. Further, the catalyst can be reused and recovered for several times without significant decrease in its activity.     

An efficient copper-free Pd(OAc)2/Ruphos-catalyzed Sonogashira coupling of 1-chloroisoquinolines in the formation of 1-alkynyl-3-substituted isoquinolines

An efficient, copper-free Sonogashira coupling reaction of 1-chloroisoquinolines and terminal alkynes, catalyzed by Pd(OAc)₂/Ruphos, in the presence of Et₃N and tetrahydrofuran leads to the formation of 1-alkynyl-3-substituted isoquinolines in good yields.     

Silica supported perchloric acid(HClO4-SiO2):A mild,reusable and highly efficient heterogeneous catalyst for the synthesis of axidoalkyl naphthols

An efficient and direct procedure has been developed for the preparation of amidoalkyl naphthols by a one-pot condensation of aryl aldehydes,2-naphthol and urea or amides,in the presence of HClO4-SiO2 as a heterogeneous catalyst.The reactions were carried out under reflux and solvent-free conditions.The present methodology offers several advantages such as excellent yields,simple procedure,easy work-up and ecofriendly reaction condition.The catalystis easily prepared,stable,reusable and efficient under the reaction conditions.     

Magnetite tethered mesoionic carbene‐palladium (II): An efficient and reusable nanomagnetic catalyst for Suzuki‐Miyaura and Mizoroki‐Heck cross‐coupling reactions in aqueous medium

In this paper, a highly active, air‐ and moisture‐stable and easily recoverable magnetic nanoparticles tethered mesoionic carbene palladium (II) complex (MNPs‐MIC‐Pd) as nanomagnetic catalyst was successfully synthesized by a simplistic multistep synthesis under aerobic conditions using commercially available inexpensive chemicals for the first time. The synthesized MNPs‐MIC‐Pd nanomagnetic catalyst was in‐depth characterized by numerous physicochemical techniques such as FT‐IR, ICP‐AES, FESEM, EDS, TEM, p‐XRD, XPS, TGA and BET surface area analysis. The prepared MNPs‐MIC‐Pd nanomagnetic catalyst was used to catalyze the Suzuki–Miyaura and Mizoroki–Heck cross‐coupling reactions and exhibited excellent catalytic activity for various substrates under mild reaction conditions. Moreover, MNPs‐MIC‐Pd nanomagnetic catalyst could be easily and rapidly recovered by applying an external magnet. The recovered MNPs‐MIC‐Pd nanomagnetic catalyst exhibited very good catalytic activity up to ten times in Suzuki–Miyaura and five times in Mizoroki–Heck cross‐coupling reactions without considerable loss of its catalytic activity. However, MNPs‐MIC‐Pd nanomagnetic catalyst shows notable advantages such as heterogeneous nature, efficient catalytic activity, mild reaction conditions, easy magnetic work up and recyclability.     

Synthesis of 3-Allyloxy(2-hydroxypropyl)-5,5-dimethylhydantoin, 1-Allyloxy(2-hydroxypropyl)-substituted Benzotriazole and Benzimidazole,and N-allyloxy(2-hydroxypropyl)-substituted Pyrrolidone,Caprolactam, and Phthalimide

The reaction of 5,5-dimethylhydantoin, benzotriazole, benzimidazole, morpholine, pyrrolidone, caprolactam, and phthalimide with allyl glycidyl ether gave the corresponding heterylhydroxypropyl allyl ethers, the structures of which were confirmed by spectral data and elemental analysis. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1135–1139, August, 2005.     

Silica supported perchloric acid （HClO4-SiO2）： A mild,reusable and highly efficient heterogeneous catalyst for the synthesis of amidoalkyl naphthols

An efficient and direct procedure has been developed for the preparation of amidoalkyl naphthols by a one-pot condensation of aryl aldehydes, 2-naphthol and urea or amides, in the presence of HClO4-SiO2 as a heterogeneous catalyst. The reactions were carried out under reflux and solvent-free conditions. The present methodology offers several advantages such as excellent yields, simple procedure, easy work-up and ecofriendly reaction condition. The catalyst is easily prepared, stable, reusable and efficient under the reaction conditions.     

Synthesis and anti-HBV activity of novel 5-substituted pyridin-2(1H)-one derivatives

<正>Four novel 5-substituted pyridine-2(1H)-one derivatives were designed and synthesized by using addition-elimination reactions.The structures of these novelly synthesized compounds were verified by ~1H NMR,ESI-MS and single crystal X-ray diffraction.Furthermore,all four compounds(most notably compound 7a) were found to be highly efficient against hepatitis B virus (HBV) in cultured HepG2 2.2.15 cell,making them promising drug candidates for potential bioactive molecule against hepatitis B.     

Selective hydrogenation and Suzuki cross‐coupling reactions of various organic substrates using a reusable polymer‐anchored palladium(II) Schiff base complex

A new polymer‐anchored Pd(II) Schiff base complex has been prepared and characterized using scanning electron microscopy, elemental analysis, atomic absorption spectroscopy, TGA and spectrometric methods such as diffuse reflectance spectra of solid and FT‐IR spectroscopy. This polymer‐anchored palladium catalyst shows excellent catalytic activity in the liquid‐phase hydrogenation reaction of styrene oxide to obtain selectively 2‐phenylethanol at normal pressure of hydrogen gas (1 atm.) at room temperature in DMF medium. We have also studied the liquid‐phase hydrogenation reaction of various organic substrates. The catalyst exhibits excellent catalytic activity for the Suzuki cross‐coupling of various substituted and non‐substituted aryl halides. The influences of various parameters were investigated to optimize reaction conditions. The reusability experiments show that the catalyst can be used five times without much loss in catalytic activity. Copyright © 2012 John Wiley & Sons, Ltd.     

2-Aminoethanesulfonic acid: An efficient organocatalyst for green synthesis of spirooxindole dihydroquinazolinones and novel 1,2-(dihydroquinazolin-3(4H)isonicotinamides in water

Abstract

A facile and efficient one-pot procedure for the preparation of spirooxindole dihydroquinazolinone derivatives and new N-(4-oxo-2-phenyl-1,2-dihydroquinazolin-3(4H)-yl)isonicotinamides from reaction between isatoic anhydride, isoniazid and substituted aldehydes catalyzed by 2-aminoethanesulfonic acid (taurine) is describe. This new protocol has the advantages of environmental friendliness, good yields, and convenient operation. The reaction proceeds efficiently using water as green solvent and nontoxic catalysts that could be efficiently reused. Together with this simple workup procedure, use of the organocatalyst, and water as solvent without the need of column chromatographic purification, are the notable features of this methodology, which make this protocol a very efficient and green alternative to the traditional methods.     

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.     

Supported benzimidazole‐salen Cu(II) complex: An efficient,versatile and highly reusable nanocatalyst for one‐pot synthesis of hybrid molecules

A novel and efficient nanocatalyst consisting of benzimidazole‐salen Cu(II) complex on surface‐modified silica (BS‐Cu(II)@SiO₂) was prepared. The heterogeneous nanocatalyst was characterized by FESEM, TEM, EDX, FT‐IR, XRD, ICP, and TGA. The nanocatalyst was used for the one‐pot synthesis of some target hybrid molecules. An efficient four component C–H bond activation/[3 + 2] cycloaddition and condensation/cyclization/aromatization sequence toward triazole‐benzimidazole derivatives is disclosed. This methodology provides a general and rapid synthetic route to some new triazole‐benzimidazole hybrids under mild reaction conditions. In addition, the heterogeneous nanocatalyst can be easily separated from the reaction mixture and used several times without noticeable leaching or loss of its catalytic activity. We believe this interesting one‐pot reaction as well as benzimidazole‐salen Cu(II) complex pave the way to the design and synthesis of other new hybrid molecules and metal catalysts, respectively.     

Supported ceric ammonium nitrate: A highly efficient catalytic system for the synthesis of diversified 2,3-substituted 2,3-dihydroquinazolin-4(1H)-ones

A practically expeditious protocol has been developed for the cascade synthesis of 2,3-dihydroquinazolin-4(1H)-ones via the condensation of 2-aminobenzamide/2-aminobenzanilide and aromatic aldehydes using a catalytic amount of silica-supported ceric ammonium nitrate. This method affords rapid transformation at room temperature with good to excellent yields.     

A novel and highly efficient polyaniline‐functionalized multiwall carbon nanotube‐supported cu(I) complex for Sonogashira coupling reactions of aryl halides with phenylacetylene

A polyaniline‐functionalized multiwall carbon nanotube‐supported Cu(I) complex was developed as an efficient catalyst for the Sonogashira reactions of aryl halides with phenylacetylene in the presence of potassium hydroxide in dimethylformamide at 135 °C under nitrogen atmosphere. The corresponding products were generated in good to excellent yields using this catalytic system. Moreover, the multiwall carbon nanotube‐supported Cu(I) catalyst was simply recycled and reused for six consecutive runs.     

A highly stable and luminescent mononuclear Cu(I) bis-{5-tert-butyl-3-(6-methyl-2-pyridyl)-1H-1, 2, 4-triazole} complex

A new emissive mononuclear homoleptic Cu(I) complex of 5-tert-butyl-3-(6-methyl-2-pyridyl)-1H-1,2,4-triazole (bmptzH),[Cu(bmptzH)₂](ClO₄) (1), has been synthesized by treatment of [Cu(PPh₃)₂(CH₃CN)₂](ClO₄) or[Cu(CH₃CN)₄](ClO₄) with the bmptzH ligand. It is revealed that complex 1 displays a distorted N₄ tetrahedral arrangement formed by two bmptzH chelates, in which bmptzH adopts a neutral bidentate chelating coordination mode using the N atom of the pyridyl ring and the 4-N not 2-N atom of the 1,2,4-triazolyl ring. It is shown that complex 1 is highly stable and exhibits good luminescence properties in solution and solid states at room temperature due to the introduction of a methyl group at the ortho-position of the pyridyl ring.     

An efficient and economical synthesis of 5-substituted 1H-tetrazoles via Pb(II) salt catalyzed [3+2] cycloaddition of nitriles and sodium azide

A simple, mild and efficient method is developed for the synthesis of 5-substituted 1H-tetrazoles. Out of three used Pb(II) catalysts, lead chloride (PbCl₂) has been found to be an efficient catalyst for [3+2] cycloaddition of NaN₃ with aromatic and aliphatic nitriles to afford 5-substituted 1H-tetrazoles. The catalyst is reusable up to four cycles with consistent activity. The cost effectiveness and easy availability of the catalyst, simple methodology, excellent yield and easy work-up are the additional advantages.