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.     

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.     

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.     

IBX promoted one-pot condensation of β-naphthol,aldehydes, and 1,3-dicarbonyl compounds

Abstract

An efficient and mild protocol has been developed for one-pot condensation of β-naphthol, aldehydes, and 1,3-dicarbolyl compounds in presence of o-iodoxybenzoic acid has been found to be an excellent catalyst for the synthesis of tetrahydrobenzo[a]xanthen-one, 1H-benzo[f]chromen-2-yl)-one via one-pot three-component condensation of β-naphthol, aldehydes, and 1,3-dicarbonyl compounds. Short reaction time, ambient conditions, simple workup, and high yield with selective manner are some of the striking features of the present protocol.     

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.     

Henry reaction in environmentally benign methods using imidazole as catalyst

Abstract

Imidazole has been found to be an efficient Lewis base catalyst for the synthesis of 2-nitroalkanols from nitro-aldol reaction in aqueous medium as well as using solvent-free grinding methods. In both cases, the products have been found in good to moderate yields without formation of any side product. Recycling of the catalyst is also possible with imidazole containing aqueous phase reaction medium (after extraction of product).     

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.     

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.

     

Morpholinium bisulfate [morH][HSO4]-promoted O,S, and Nacylation at room temperature

Abstract

Morpholinium bisulfate [morH][HSO₄] found to be highly inexpensive, efficient, and reusable catalyst to promote the acylation of phenols, thiols, alcohols, and amines in presence of acetic anhydride under solvent-free condition with excellent yields by stirring at room temperature. Present methodology deals with remarkable features of mild reaction condition, high yielding, shorter reaction time, easy workup, and more importantly, environmentally benign.     

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.     

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.     

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.

     

Activated fly ash-catalyzed synthesis of naphthyl-substituted cyclohexenone carboxylates,indazolonols, and nitro hydrazones in “dry media”

Abstract

An efficient and rapid synthesis of an array of naphthyl-substituted cyclohexenone carboxylates, indazolonols, and nitrohydrazones by using activated fly ash as catalyst in dry media is described. All the synthesized compounds were characterized by their melting point, elemental analysis, mass spectrometry, Fourier transform infrared, one-dimensional nuclear magnetic resonance (¹H and D₂O exchanged ¹H and ¹³C), and two-dimensional homonuclear correlation (HOMOCOR) and heteronuclear single quantum coherence (HSQC) spectroscopic data. Compared to classical conditions, this new protocol had the advantage of excellent yields, mild reaction conditions, simple workup, and short reaction times. Also, the catalyst could be reused up to four runs without any reduction in efficiency, making the process greener and environmentally benign.      

Multicomponent eco-friendly synthesis of 3,4-dihydropyrimidine-2-(1H)-ones using an organocatalyst Lactic acid

Abstract

Biginelli compounds 3,4-dihydropyrimidine-2-(1H)-ones are synthesized in high yields via eco-friendly simple reaction procedure using Lactic acid: organocatalyst. The new method reported herein is green and is free of formation of any hazardous by products. The process has significant advantages over other reported methods.     

A new protocol for Biginelli (or like) reaction under solvent-free grinding method using Fe (NO3)3.9H2O as catalyst

Abstract

A new protocol for Biginelli (or like) reaction has been developed under solvent-free grinding method using catalytic amount of hydrated ferric nitrate or clayfen. The advantage of this novel protocol lies in the avoidance of organic solvent, high yield, energy efficiency, variation of substrates, and use of inexpensive catalyst. The recycling of catalyst is also possible with clayfen for more than three times. Furthermore, the catalytic activity of ferric nitrate retains its efficiency in methanol and acetone as reaction medium.     

Knoevenagel reaction: alum-mediated efficient green condensation of active methylene compounds with arylaldehydes

Abstract

A solvent-free stirred mixture of active methylene compounds, arylaldehyde and 10 mol% alum at 80°C afforded Knoevenagel products in excellent yields. The use of a green catalyst, the solvent-free conditions, and shorter reaction times are the main features of this efficient protocol.     

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.     

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.     

An eco-friendly procedure for the efficient synthesis of arylidinemalononitriles and 4,4′-(arylmethylene)bis(3-methyl-1-phenyl-1H-pyrazol-5-ols) in aqueous media

Abstract

Commercially available lithium hydroxide monohydrate (LiOH·H₂O) was found to be a novel “dual activation” catalyst for Knoevenagel condensation between malononitrile (1) or 3-methyl 1-phenyl-1H-pyrazol-5-(4H)-one (6) with aromatic aldehydes 2a–e leading to an efficient and easy synthesis of arylidenemalononitriles 3a–d and 4,4′-(arylmethylene)bis(3-methyl-1-phenyl-1H-pyrazol-5-ols) 7a–c in short times. The reaction of aryl aldehydes with malononitrile afforded excellent yields after 1–6 min in aqueous media at room temperature. In case of 3-methyl-1-phenyl-1H-pyrazol-5-(4H)-one (6) and aromatic aldehydes afforded good yields after 60–75 min at 90°C.     

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.