A novel approach toward thioester bond formation mediated by N,N’ -diisopropylcarbodiimide in water

Abstract

A simple and efficient method has been developed for the synthesis of thioesters from carboxylic acids and thiols using N,N'-diisopropylcarbodiimide (DIC). The reactions were carried out in water as an environmentally friendly and green solvent. The developed procedure presents an economic, efficient, mild, and very simple protocol for thioesterification reaction in aqueous media.     

Silica-supported Preyssler nano particles: a green,reusable and highly efficient heterogeneous catalyst for the synthesis of carbamatoalkyl naphthols

Abstract

An efficient and green procedure has been developed for the preparation of carbamatoalkyl naphthols by the one-pot condensation of aryl aldehydes, β-naphthol, and methyl carbamate in the presence of silica-supported Preyssler nano particles as a heterogeneous catalyst under solvent-free conditions. The present methodology offers several advantages such as excellent yields, simple procedure, easy work-up, and eco-friendly reaction conditions. The catalyst is easily prepared, stable, reusable, and efficient under the reaction conditions.     

A Convenient Synthesis of Thioacetates and Thiobenzoates Using Silica-Gel Supported Potassium Thioacetate

Abstract

A simple and efficient procedure has been developed for the synthesis of thioesters by a reaction of alkyl halides with silica-gel supported potassium thioacetate or thiobenzoate under mild conditions.     

EcoFriendly Synthesis of Tetrahydropyrimidine Derivatives in Aqueous Medium Under Ultrasonic Irradiation

Abstract

A simple, efficient, and ecofriendly procedure was developed for the synthesis of 2-substituted 1,4,5,6-tetrahydropyrimidine derivatives catalyzed by N-bromosuccinimide using ultrasonic irradiation in aqueous medium. Prominent advantages of this new method are good yields, aqueous medium, short reaction times, and easy workup procedure. The compounds were characterized by infrared, NMR, liquid chromatography–mass spectrometry, and elemental analyses.     

A Fast and Large-Scale Synthesis of 3-Formyl-2-mercaptoquinolines

A convenient, efficient, and inexpensive procedure for the synthesis of 3-formyl-2-mercaptoquinolines 2a–l has been developed by a simple one-pot reaction of 3-formyl-2-chloroquinolines 1a–l with sodium sulfide and hydrochloric acid in ethanol. The structures of all the synthesized compounds were elucidated on the basis of elemental analyses and IR, ¹ H NMR, and mass spectral data.     

THE KNOEVENAGEL CONDENSATION REACTION OF AROMATIC ALDEHYDES WITH MALONONITRILE BY GRINDING IN THE ABSENCE OF SOLVENTS AND CATALYSTS

ABSTRACT

An improved Knoevenagel condensation reaction of aldehydes and malononitrile can be achieved by grinding at room temperature in the absence of solvents and catalysts. This process is simple, efficient, economical, and environmentally benign. Compared to reactions carried out by microwave irradiation, this procedure is completely free from organic solvents during both the reaction and separation of the product.     

Chitosan-SO3H (CTSA) an efficient and biodegradable polymeric catalyst for the synthesis of 4,4′-(arylmethylene)bis(1H-pyrazol-5-ol) and α-amidoalkyl-β-naphthol’s

Abstract

An efficient, green procedure for the synthesis of 4,4′-(arylmethylene)bis(1H-pyrazol-5-ol) and α-amidoalkyl-β-naphthol’s using biodegradable polymeric catalyst chitosan-SO₃H (CTSA), is operationally easy to prepare by mixing chitosan and chlorosulfonic acid. This catalyst displays excellent catalytic activity and reusable for five subsequent reactions without significant loss of catalytic activity. This protocol proceeds with short reaction times, at mild temperatures, in a solvent-free reaction, and generally with high yields. We present herein a practical, efficient and simple procedure with a broad substrate scope that allows access to two different reactions 1H-pyrazole-5-ol and α-amidoalkyl-β-naphthol’s core unit.     

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.     

AlCl3/PCC-SiO2-Promoted Oxidation of Azaindoles and Indoles

Abstract

A simple and efficient method is described for the oxidation of 7-azaindoles and indoles to 7-azaisatins and isatins using pyridinium chlorochromate–silica gel (PCC-SiO₂) with the aid of Lewis acid catalyst aluminium chloride (AlCl₃) in dichloroethane. Simplicity of the reaction conditions, easy workup procedure, and good yields are the key features of this protocol.     

An Efficient and Simple Method for Diazotization-Thiocyanation of Aryl Amine using Cross-Linked Poly (4-Vinylpyridine) Supported Thiocyanate Ion

Abstract

An efficient and simple method for the facile synthesis of arylthiocyanates via diazotization-thiocyanation of aryl amines using cross-linked poly (4-vinylpyridine) supported thiocyanate ion is described. Various primary aromatic amines, with electron-withdrawing and electron-donating groups, were transformed into aryl thiocyanates in high to excellent yields in a short reaction time. The present procedure offers advantages such as short reaction time, simple reaction work-up, and the polymeric reagents can also be regenerated and reused for several times without significant loss of their activity.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

Indion 190 resin: efficient,environmentally friendly,and reusable catalyst for synthesis of benzimidazoles,benzoxazoles, and benzothiazoles

Abstract

An efficient and mild protocol has been developed for the preparation of benzimidazoles, benzoxazoles, and benzothiazoles from reactions of aldehydes with o-substituted aminoaromatics in the presence of catalytic amount of Indion 190 resin. Short reaction time, ambient conditions, simple work-up procedure, high yield, easy availability, reusability, and use of an eco-friendly catalyst are some of the striking features of the present protocol.     

Silica-Supported Perchloric Acid (HClO4-SiO2): An Efficient Catalyst for the Preparation of β-Amido Carbonyl Compounds Using Multicomponent Reactions

A new, one-pot, efficient, three-component condensation of benzaldehyde derivatives, enolizable ketones, acetyl chloride, and acetonitrile or benzonitrile in the presence of silica-supported perchloric acid as an effective catalyst for the synthesis of β-amido carbonyl compounds is described. The present methodology offers several advantages, such as good yields, short reaction times, and simple workup procedure.     

Ionic liquid [omim][NO3], a green medium for room-temperature synthesis of benzothiazinone derivatives in one pot

Abstract

An efficient one-pot procedure is developed at room temperature for the reaction of 2-aminothiophenols with 2-bromoalkanoates in ionic liquid (IL) [omim][NO₃], providing the corresponding benzothiazin-3-one derivatives in high yields without using any other base or additive. Products are easily obtained by simple extraction of the reaction mixtures with Et₂O. In most cases, evaporation of the volatile contents leads to precipitation of the products and therefore the use of chromatographic separations is avoided. The IL is then recovered and reused in next reactions without loosing its activity. The procedure is successfully extended to the synthesis of the respective 2-carboxylate derivatives via the reaction of 2-aminothiophenols with 2-bromomalonates.     

One-Pot Multicomponent Reactions for the Efficient Synthesis of Highly Functionalized Dihydropyridines

Abstract

An efficient, atom-economic, one-pot protocol has been developed for the synthesis of highly functionalized dihydropyridines via four-component reactions of aromatic aldehydes, arylamines, malononitrile, and dimethylacetylenedicarboxylate in the presence of sodium hydroxide in ethanol. This domino reaction proceeded smoothly in good to excellent yields and offered several advantages, including short reaction time, simple experimental procedure, and applicability to a broad range of substrates.

Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file.     

NaF-catalyzed efficient one-pot synthesis of dihydropyrano[2,3-c]pyrazoles under ultrasonic irradiation via MCR approach

Sodium fluoride was identified as an efficient catalyst for the preparation of series of dihydropyrano [2,3-c]pyrazoles (4a–l) by the three-component condensation of 3-Methyl-1-phenyl-2-pyrazoline-5-one (1), aromatic aldehydes (2) and malononitrile (3) in aqueous methanol at ambient temperature under ultrasonication. The cost and efficacy of the catalyst, mild reaction conditions, simple workup procedure, less reaction time and higher yields of the product with analytical purity keeping this protocol superior to the previously reported ones. Structures of all the compounds were in agreement with their spectroscopic data (¹H NMR, ¹³C NMR) and elemental (CHN) analyses.     

Efficient “on water” green route heterocyclization of thiosemicarbazones with DMAD

A simple, efficient, and eco-friendly procedure for the synthesis of thiazolidin-4-one derivatives in water from cyclocondensation reaction of thiosemicarbazone derivatives and dimethylacetylene dicarboxylate (DMAD) in good yield is reported. The regiochemistry of the cyclized products is established by elemental analysis, IR, NMR, and mass spectral data. A single crystal X-ray diffraction study of a representative compound, 3f, is reported.     

Green catalytic synthesis of 14-aryl-14H-dibenzo[a,j]xanthenes using recyclable mesoporous zirconia modified with tungstophosphoric acid

Abstract

A simple and efficient procedure has been developed for the preparation of aryl-14H-dibenzo[a,j]xanthenes by a one-pot condensation of 2-naphthol and aryl aldehydes, in the presence of mesoporous zirconia modified with tungstophosphoric acid (ZrTPA60B_T100), to be used as a heterogeneous catalyst in a solvent-free medium using conventional heating. The present approach offers the advantages of clean reaction, simple methodology, short reaction time, and high yield. The reaction work-up is very simple and the catalyst can be easily separated from the reaction mixture and reused several times in subsequent reactions without appreciable loss of the catalytic activity.     

Water mediated synthesis of various [1,3]oxazine compounds using alum as a catalyst

Abstract

A simple, efficient, and practical procedure for the synthesis of various substituted 2,3-dihydro-2-phenyl-1H-naphtho[1,2-e][1,3]oxazines and 3,4-dihydro-3-phenyl-2H-naphtho[2,1-e][1,3]oxazines using KAl(SO₄)₂ 12H₂O (alum) as a non-toxic, reusable, inexpensive, and easily available catalyst is described using water as a solvent. These improved reaction conditions allow the preparation of a wide variety of substituted [1,3]oxazines in high yields and purity under mild reaction conditions.     

Facile and Efficient Deoxygenation of Amine‐N‐oxides with Gallium in Water

Abstract

A facile and efficient procedure for the deoxygenation of amine‐N‐oxides with gallium metal in water is described. The experimental procedure is quite simple and the products are obtained in high yields without any activating agent.     

One-Pot Synthesis of Dihydropyrimidine-Thione Derivatives Using Tungstate Sulfuric Acid (TSA) as a Recyclable Catalyst

Abstract

An efficient, simple, and environmentally benign procedure for the one-pot synthesis of 3,4-dihydropyrimidine-2-(1H) thione derivatives that entails the three-component condensation of appropriate aryl aldehydes, β-dicarbonyls, and thiourea in the presence of catalytic amount of tungstate sulfuric acid under solvent-free conditions was reported. This method has many advantages including excellent yields, short reaction time, and simple work-up procedure.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements for the following free supplemental resource: 1H, 13C NMR and Mass Spectra for 5b, 5g, 5j, 5i, 5l (S2-S16). Additional Characterization Data (S17-18).