PEG-600-mediated,green and efficient,tandem syntheses of N-subtituted-2-styrylquinazolin-4- ones

Polyethylene glycol (PEG)-mediated, green and efficient, tandem syntheses of N-subtituted-2-styrylquinazolinones are being reported. Condensation of anthranilamide (1) with acetic anhydride in PEG-600, at 100°C for 1 hr gave 2-methyl-3H-quinazoline-4-one (2). Treatment of 2 with benzaldehydes in PEG-600, at 100°C for 2–3 hr, gave 2-styrylquinazolinone-4-ones (3) in excellent yields. Treatment of 3 (a–d) either with dimethyl sulfate (DMS), diethyl sulfate (DES), or with Ph-CH₂-Cl, individually in PEG-600, at 100°C for 1–2 hr without using any base, followed by simple processing resulted in N-substituted-2-styrylquinazolin-4-ones 5 (a–l). In an alternative approach, reaction of 4 (a–c) with benzaldehydes in PEG-600, at 100°C for 1–2 hr, without using any base, followed by simple processing resulted in 5 (a–l). 4 (a–c) were prepared by treatment of 2 with either DMS, DES, or with Ph-CH₂-Cl, individually, in the presence of PEG-600 as reaction medium, at 100°C for 1–2 hr without using any base. Both the sequence of reactions, 1 2 3 5 or 1 2 4 5 could be carried out in tandem in an efficient manner in PEG-600 without the isolation of any intermediates. The structures of all the new compounds synthesized in this work have been established on the basis of their spectroscopic data and analytical data.     

Lithium bromide as an efficient,green, and inexpensive catalyst for the synthesis of quinoxaline derivatives at room temperature

Abstract

An efficient, simple, and green procedure for the synthesis of quinoxaline derivatives is described. The condensation of 1,2-diamines with 1,2-diketones using lithium bromide (LiBr) in H₂O/EtOH as a green reaction media at room temperature affords the title compounds in high to excellent yields and in short reaction times.     

Silica supported perchloric acid (HClO4-SiO2): a green,reusable, and highly efficient heterogeneous catalyst for the synthesis of thioethers under solvent-free conditions at room temperature

Abstract

A highly efficient and clean procedure is described for the synthesis of thioethers with excellent yields under solvent-free conditions at room temperature using a catalytic amount of HClO₄-SiO₂. The catalyst is easily prepared, stable, and reusable without much loss of catalytic activity, and is efficient under the reaction conditions.     

Synthesis of β-amino alcohols by ring opening of epoxides with amines catalyzed by cyanuric chloride under mild and solvent-free conditions

Abstract

The 2,4,6-trichloro-1,3,5-triazine catalyzed synthesis of β-amino alcohols by aminolysis of epoxide under solvent-free condition is described. Mild reaction conditions, short reaction times, inexpensive and readily available catalysts, and excellent yields of the products with high regioselectivity are attractive features of this methodology.     

Novel one-pot synthesis of 1,2,4-triazolidin-3-thiones comprising piperidine moiety

Abstract

A simple synthetic strategy for the synthesis of piperidinyl spiro-1,2,4-triazolidin-3-thiones 11–15 is proposed, exploiting microwave activation coupled with solvent-free reaction conditions catalyzed by NaHSO₄.SiO₂ heterogeneous catalyst is described.     

A very high yielding and facile alkaline earth metals homogeneous catalysis of Biginelli reaction: an improved protocol

Abstract

A high yielding and facile Biginelli reaction for the synthesis of 3,4-dihydropyrimidin-2(1H)-ones and thiones, using inexpensive and available alkaline earth metal chlorides (MgCl₂, CaCl₂, SrCl₂ and BaCl₂) and acetic acid as the solvent in a homogeneous catalytic reaction, is reported.     

TFAA-H3PO4 mediated rapid and single-step synthesis of mutual prodrugs of paracetamol and NSAIDs

Abstract

A clean and operationally simple method has been developed for the preparation of mutual prodrug using paracetamol and various nonsteroidal anti-inflammatory drugs. The methodology involves use of TFAA/H₃PO₄ in acetonitrile and a variety of mutual prodrugs has been prepared in good yields by using this single-step C–O bond forming reaction.

     

Water mediated efficient one-pot synthesis of bis-(4-hydroxycoumarin)methanes

Abstract

Manganous chloride (MnCl₂·4H₂O) has been used as an efficient catalyst for an improved and rapid one-pot synthesis of bis-(4-hydroxycoumarin)methanes in excellent yields using water as a reaction medium. This aqueous mediated reaction of various aromatic and heteroaromatic aldehydes with 4-hydroxycoumarin using catalytic amounts of manganous chloride avoids the use of expensive, corrosive reagents, toxic solvents, and provides operational simplicity.     

Brønsted acidic ionic liquid [HMIm]BF4 promoted simple and efficient one-pot green synthesis of isoxazolyl-1,3-benzoxazines at ambient temperature

Abstract

Brønsted acidic ionic liquid [HMIm]BF₄ has been used as a nonvolatile, ecofriendly solvent, and catalytic medium for the one-pot green synthesis of isoxazolyl-1,3-benzoxazines. The reaction afforded excellent yield in short reaction time, and avoids multistep synthesis. The easy of recyclability of the IL makes the reaction economically and potentially viable for commercial applications.     

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.     

An efficient green protocol for the synthesis of chalcones by a Claisen–Schmidt reaction using bismuth(III)chloride as a catalyst under solvent-free condition

Abstract

An environmentally benign protocol for the synthesis of chalcones by the Claisen–Schmidt condensation of aldehydes with ketones using eco-friendly non-toxic bismuth(III)chloride catalyst under solvent-free condition is reported. In this protocol, the reaction time is very short, yields are high, and there are no other pollutants formed.     

A highly efficient,operationally simple and selective thia-Michael addition under solvent-free condition

Abstract

The rapid and very simple conjugate addition of thiols to α,β-unsaturated carbonyl compounds under solvent-free conditions in the presence of catalytic amount of lithium hydroxide at room temperature is reported. The reaction of aryl, alkyl, aliphatic, and hindered thiols with chalcone, enone, and nitrostyrene gave the corresponding Michael adducts with significant advantages, such as high conversions, short reaction time, mild reaction conditions, low cost, simple catalyst, and high to quantitative yields with excellent chemoselectivity.

     

An efficient green protocol for the synthesis of 2-aryl substituted benzothiazoles

Abstract

Cyclocondensation of 2-aminothiophenol and various aryl/heteryl aldehydes was carried in polyethylene glycol-400 as a catalyst and reaction medium at room temperature to obtain 2-aryl substituted benzothiazoles with excellent yields.     

Reusable polymer-supported copper catalyst for one-pot synthesis of 1-alkyl- and 1-aryl-1,2,3-triazoles: green,simple, and effective

Abstract

Polymer-supported copper-catalyzed one-pot synthesis of 1,4-disubstituted 1-alkyl- and 1-aryl-1,2,3-triazoles via 1,3-dipolar cycloaddition of alkyl halides or arylboronic acids, sodium azide, and phenylacetylene has been developed. Reactions went smoothly at room temperature using PEG/H₂O or methanol as solvent to afford the corresponding triazoles in good to excellent yields. The catalyst could be recovered by simple filtration and reused several times with slightly decrease in its activity.     

Reaction of bromine with 4,5-dimethyl-1,4-cyclohexadiene-1,2-dicarboxylic acid: a green chemistry puzzle for organic chemistry students

Abstract

Bromination of an alkene is a typical addition reaction covered in an introductory organic chemistry course and laboratory. In this undergraduate organic chemistry laboratory exercise, students studied the bromination of a 4,5-dimethyl-1,4-cyclohexadiene-1,2-dicarboxylic acid. The reaction has an unexpected outcome as bromination yields the aromatic product, 4,5-dimethylphthalic acid. Green chemistry modification involves application of a “bromide/peroxide reaction” with NaBr/H₂O₂ in an acidic medium as an in situ source of bromine. The experiment was carried out as a two-day exercise and the students integrated molecular modeling, interpretation of mass spectra, knowledge of stability of organic compounds, and knowledge of the reaction mechanisms of addition and elimination to explain the experimental outcome.     

One-pot multicomponent synthesis of polyhydroquinolines under catalyst and solvent-free conditions

Abstract

An efficient one-pot condensation has been developed for the synthesis of polyhydroquinolines via a four component coupling reaction of aldehyde, dimedone, ethyl acetoacetate, and ammonium acetate under catalyst and solvent-free conditions. Non-hazardous experiment procedure, operational simplicity, mild reaction conditions, and the compatibility with various functional groups represent the advantages of the present method.     

Uncatalyzed synthesis of thiomorpholide using polyethylene glycol as green reaction media

Abstract

Polyethylene glycol-600 was used as an efficient and recyclable solvent for the one-pot three component condensation reactions of aryl alkyl ketones, sulfur, and morpholine to produce the corresponding thiomorpholide. This protocol has advantages of high yields, short reaction times, mild reaction conditions, minimal environmental pollution, and simple work up procedure.     

Efficient Prins cyclization in environmentally benign method using ion exchange resin catalyst

Abstract

Amberlyst-15^® (H⁺) resin catalyzes efficient one-pot solvent free Prins cyclization of an aldehyde and a homoallylic alcohol to yield dihydropyrans and 4-hydroxytetrahydropyrans. The products, which display interesting olfactory property, are obtained under mild condition and by simple work up. The recovered resin can be used repeatedly .