DMAP-catalyzed cascade reaction: one-pot synthesis of benzofurans in water

A series of benzofurans were efficiently synthesized in good to excellent yields using 4-dimethylaminopyridine (DMAP) catalyzed cascade reaction between salicylaldehydes and halogenated ketones in water at 80 °C opened atmosphere.     

Green synthesis of Fe3O4/ZnO magnetic core-shell nanoparticles by Petasites hybridus rhizome water extract and their application for the synthesis of pyran derivatives: Investigation of antioxidant and antimicrobial activity

In this research, Fe₃O₄/ZnO magnetic core-shell nanoparticles (Fe₃O₄/ZnO MCNPs) were synthesized through a green method using Petasites hybridus rhizome water extract as a reducing and stabilizing agent. The morphology and size of the Fe₃O₄/ZnO MCNPs was identified by X-ray diffraction, scanning electron microscopy, and Energy-dispersive X-ray spectroscopy (EDX) analysis. The catalytic activity of the Fe₃O₄/ZnO MCNPs was evaluated in the efficient and green preparation of pyran derivatives in excellent yield using three-component reactions of dimedone, aldehydes, and malononitrile in ethanol at room temperature. The ability of some synthesized compounds to scavenge the 2,2-diphenyl-1-picrylhydrazyl radical was measured and the results proved this observation. Moreover, the antimicrobial activity of some synthesized compounds was proved by employing the disk diffusion test on Gram-positive and Gram-negative bacteria. The results for the disk diffusion test showed that compounds ( 4c, 4d, 4f and 4g ) prevented bacterial growth.     

Chemical composition and antioxidant activity of the essential oil of aerial parts of Petasites albus from Iran: a good natural source of euparin

The chemical composition of the essential oil of Petasites albus (known as 'Baba Adam' in Iran) was investigated by capillary gas chromatography and gas chromatography-mass spectrometry for the first time. Twenty components were identified, accounting for 99.7% of the oil composition. The major compounds were euparin (73%), α-eudesmol (13.2%) and β-selinene (4.5%). Euparin, the main component of the essential oil, was isolated and characterised by spectroscopic techniques. The antioxidant activities of the essential oil and euparin were evaluated by using the 2,2-diphenyl-1-picrylhydrazyl radical scavenging assay and are shown to exhibit a moderate antioxidant activity.     

Three-component synthesis of novel trifluoromethyl-containing tetrahydropyran derivatives

l-Proline-catalyzed reaction of ethyl 4,4,4-trifluoroacetoacetate, cinnamaldehyde and anilines provide a novel method for preparation of ethyl-6-(arylamino)-2-hydroxy-4-phenyl-2-(trifluoromethyl)tetrahydro-2H-pyran-3-carboxylate derivatives in good yields. The reaction was conducted by initial Michael addition, followed by intra-molecular cyclization under mild conditions. The structure of a typical ethyl-2-hydroxy-4-phenyl-6-(m-tolylamino)-2-(trifluoromethyl)tetrahydro-2H-pyran-3-carboxylate (4h) was confirmed by XRD analysis. A plausible mechanism is presented.     

Facile and efficient synthesis of polyfunctionalized benzofurans: three-component coupling reactions from an alkynylsilane, an o-hydroxybenzaldehyde derivative, and a secondary amine by a Cu(I)-Cu(II) cooperative catalytic system

The combination of 5 mol % Cu(OTf)₂ and CuCl in the presence of DMAP effectively catalyzed a three-component coupling reaction involving an alkynylsilane, an o-hydroxybenzaldehyde derivative, and a secondary amine. The reaction proceeded via intramolecular 5-exo-dig cyclization, resulting in direct synthesis of the corresponding benzofuran derivatives in moderate to excellent yields.     

One-pot three-component reaction for the synthesis of novel series of fully substituted 1,3,4-oxadiazole derivatives bearing pyridine moiety

(N-isocyanimino)triphenylphosphorane, 2-pyridinecarbaldehyde, and aromatic carboxylic acids (benzoic acid, 3-methylbenzoic acid, 4-methylbenzoic acid, 3-methoxybenzoic acid, 1-naphthoic acid, and 2-naphthoic acid) undergo a 1:1:1 addition reaction under mild conditions in a one-pot reaction to afford novel series of fully substituted 1,3,4-oxadiazole derivatives in good yields.     

Titanium tetrachloride promoted cyclodehydration of aryloxyketones: Facile synthesis of benzofurans and naphthofurans with high regioselectivity

An efficient and facile method for the synthesis of a broad series of benzofurans and naphthofurans is described. The direct intramolecular cyclodehydration of aryloxyketones in the presence of titanium tetrachloride affords the corresponding benzofurans and naphthofurans with good regioselectivity and yields.     

Domino rhodium(I)-catalysed reactions for the efficient synthesis of substituted benzofurans and indoles

Rhodium(I) catalysts promote the transformation of o-alkynyl phenols and anilines to the corresponding benzo[b]furans and indoles. The reaction is postulated to proceed via a transient 3-rhodium heterocycle intermediate, which can be trapped with suitable electrophiles to give poly-substituted heterocycles. In the case of mono-substituted electron-withdrawn electrophiles, excellent yield and selectivity for conjugate addition versus Heck-Mizoroki reaction can be achieved. In the case of 2-alkynyl pyridine electrophiles, novel 2-(benzofuran-3-yl)vinylpyridines are formed.     

Efficient synthesis of novel tricyclic fused pyranothiazolopyrimidine derivatives via isocyanide-based three-component reactions

An efficient and facile one-pot synthesis is described for the preparation of novel tricyclic fused pyranothiazolopyrimidines containing both biologically active thiazolopyrimidine and pyranopyrimidine templates via three-component reaction involving an isocyanide with a dialkylacetylenedicarboxylate (DAAD) and 2,3-dihydro-5H-[1,3]thiazolo[3,2-a]pyrimidine-5,7(6H)-dione, in high yields.     

A novel one-pot three-component synthesis of benzofuran derivatives via Strecker reaction: Study of antioxidant activity

Abstract

A three-component Strecker-type reactions was applied for the synthesis of benzofuran derivatives through the reaction of 1-(6-hydroxy-2-isopropenyl-1-benzofuran-yl)-1-ethanone (euparin), primary amines and trimethylsilyl cyanide (TMSCN) in the presence of catalytic amount of ZnO-nanorods (ZnO-NR) and piperidine in acetonitrile at room temperature. The method has proved to be synthetically simple, and effective with high atom economy and yield. The catalyst also revealed significant reusability. Moreover, the antioxidant activity and free radical scavenging capacity of the newly synthesized such as 4a, 4c, 6a and 6c was screened using free radical scavenging 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP) assays and compared with hydroxytoluene (BHT) and tert-butylhydroquinone (TBHQ). These compounds exhibit good DPPH radical scavenging and ferric reducing antioxidant power (FRAP) assays.     

Green synthesis and antioxidant activity of new PEGylated ferulic acids

PEGylation of ferulic acid is described through a green esterification process involving poly(ethylene glycol) (PEG) with three different average molecular weights (200, 400 and 1000 g/mol) as both reactive and solvent. Esterification with PEG400 and PEG1000 leads to original compounds soluble in all proportions in water. These new compounds display an antioxidant activity similar to that of ferulic acid.     

A novel one-pot, three-component reaction for the synthesis of isocoumarin-condensed pyrazoles

The one-pot, three-component reaction of substituted homophthalic anhydrides with hydrazine in DMF as solvent and reactant, at reflux temperature, afforded isochromeno[3,4-c]pyrazole-5(2H)-one derivatives in high yields. The mechanism and roles of the substrates were investigated and it was found that cyclic hydrazides were formed as intermediates.     

A novel and efficient domino reaction for the one-pot synthesis of spiro-2-aminopyrimidinones

A novel and efficient protocol is developed for the synthesis of various spiro-2-amino pyrimidinones via the three-component condensation of alkyl cyanoacetates, guanidinium carbonate and N-substituted 4-piperidinones in ethanol at reflux. High yields, neutral conditions, and short reaction times are advantages of this method.     

Design, synthesis and antitumor activity of a series of novel coumarin-stilbene hybrids, the 3-arylcoumarins

A series of novel coumarin-stilbene hybrids called 3-arylcoumarins were synthesized via Perkin reaction and evaluated as potential antitumor agents. The results showed that some compounds exhibited in vitro activity against KB, KV, MCF-7, MCF-7/ADR cell lines to some extent. Compound 3a showed remarkable effect against KB tumor cells with an IC50 value of 5.18 μmol/L.     

2D ZnO/Fe3O4 nanocomposites as a novel catalyst-promoted green synthesis of novel quinazoline phosphonate derivatives

In this research a novel and efficient procedure for the preparation of phosphonate derivatives using the reaction of 2,4-dihydroxyacetophenone, isopropenylacetylene, 2-amino-N-alkyl benzamide, dialkyl acetylenedicarboxylates and trimethyl phosphite or triphenyl phosphite in the presence of reusable 2D ZnO/Fe₃O₄ nanocomposites in water at room temperature was investigated. The 2D ZnO/Fe₃O₄ nanocomposites were synthesized using ionic liquid [OMIM]Br as a stabilizer and soft template. In addition, the power of antioxidant for some prepared compounds was studied using trapping of radicals by DPPH and a ferric reduction activity potential experiment. As a result, compound 6f displayed a noteworthy power for trapping of free radicals and 6b exhibited excellent reducing power compared with standards (BHT and TBHQ). Moreover, the antimicrobial power of some prepared quinazolinone phosphonates was proved by employing the disk diffusion experiment on two kinds of bacteria, Gram-positive and -negative bacteria. The obtained outcomes of disk diffusion test showed that these compounds prevented bacterial growth. Some advantages of this procedure are: short time of reaction, high yields of product and easy separation of catalyst and products.     

Facile synthesis of sulfur-substituted allenes by a three-component reaction

The three-component reaction of lithium alkylthiolate, 1-alkynylphosphine oxide and aldehyde in THF affords sulfur-substituted allenes in good to excellent yield.     

A simple and efficient approach to the synthesis of highly functionalized fused benzochromenes

Protonation of the reactive intermediates produced in the reaction between tert-butyl isocyanide and dimethyl acetylenedicarboxylate or dibenzoylacetylene, by 1-naphthol, 2-naphthol, 2,3-dihydroxynaphthalene, 2,7-dihydroxynaphthalene or 4-methyl-8-hydroxycoumarin leads to vinylnitrilium cations, which undergo carbon-centered Michael type addition with the conjugate base of the naphthols to produce highly functionalized benzochromenes.     

New synthesis of (−)- and (+)-actinobolin from d-glucose

The total synthesis of (−)-actinobolin 2, an antipode of the natural product starting from d-glucose is described. A three-component coupling reaction of a functionalized cyclohexenone (+)-6, derived from d-glucose by way of Ferrier's carbocyclization, with vinyl cuprate and an aldehyde (R)-5 effectively constructed the carbon framework of 2 in a highly stereoselective manner. The formal synthesis of the natural enantiomer 1 from d-glucose was also achieved.     

New synthesis of benzo[b]furan and indole derivatives from 1,1-dibromo-1-alkenes using a tandem Pd-assisted cyclization-coupling reaction

We report a new flexible method for the synthesis of 2-functionalized benzo[b]furans and indoles from readily available o-(2,2-dibromovinyl)-phenol, -aniline or -acetanilide using a tandem Pd-assisted cyclization-coupling reaction.     

Practical and high stereoselective synthesis of 3-(arylmethylene)isoindolin-1-ones from 2-formylbenzoic acid

Practical and high stereoselective synthesis of 3-(arylmethylene)isoindolin-1-ones is reported. The synthetic method involves the preparation of dimethyl isoindolin-1-one-3-yl-phosphonates by a ‘one-pot’ three-component reaction of 2-formylbenzoic acid with 4-methoxybenzylamine or aminoacetaldehyde dimethyl acetal and dimethyl phosphite under solvent and catalyst free-conditions, followed by a Horner reaction with several aryl aldehydes.