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.     

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 new and efficient one-pot synthesis of 2-hydroxy-1,4-dihydrobenzoxazines via a three-component Petasis reaction

The secondary amines synthesized by the reaction between 2-aminophenols and aromatic aldehydes, via the reduction of the corresponding imines, were employed in the synthesis of new 2-hydroxy-2H-1,4-benzoxazine derivatives through a one-pot Petasis multicomponent reaction in good to excellent yields.     

An efficient synthesis of thiazol-2-imine derivatives via a one-pot,three-component reaction

A simple and highly efficient one-pot, three-component procedure for the synthesis of thiazol-2-imines, via the reaction of aromatic α-bromoketones, primary amines, and phenyl isothiocyanate in the presence of a catalytic amount of triethylamine, is described.     

A novel three-component one-pot pyrimidine synthesis based upon a coupling-isomerization sequence

[reaction: see text] 2,4,6-Tri(hetero)aryl-substituted pyrimidines can be readily synthesized in a three-component one-pot process based upon a coupling-isomerization sequence of an electron-poor (hetero)aryl halide and a terminal propargyl alcohol subsequently followed by a cyclocondensation with amidinium salts.     

A novel one-pot, three-component reaction: formation of tricyclic 1,2-dihydropyridines via mesomeric betaines

A one-pot, three-component reaction of pyridine, thiophthalimide and acyl chloride gives novel tricyclic 1,2-dihydropyridines regio- and stereoselectively, in which a mesomeric betaine would be a key intermediate for [4+2]-cycloaddition reaction with thiocarbonyl compounds.     

A novel three-component one-pot synthesis of 1H-imidazol-4-yl-pyridines

A novel three-component, one-pot condensation yielding 1H-imidazol-4-yl-pyridines from aldehydes, o-picolylamines, and isocyanides is described. The scope and limitations of the reaction have been investigated.     

Synthesis of 1,2-disubstituted-3-alkylidenylpyrrolidines via a one-pot three-component reaction

Olsson’s three-component reaction of cyclopropylketones, aldehydes, and primary amines was investigated for application to parallel synthesis. Using an excess of Et₂AlI at elevated temperatures, pyrrolidines 4, the initial products reported by Olsson and co-workers, could be completely converted to pyrrolium salts 5, by a reaction sequence involving a retro-aza-Michael addition followed by iminium salt formation. The pyrrolium salts 5 were then cleanly reduced in situ by NaBH(OAc)₃ to give 3-alkylidenylpyrrolidines 6. In summary, this one-pot three-component reaction provided an efficient synthetic route to 3-alkylidenylpyrrolidines.     

A facile method for the synthesis of nicotinonitriles from ketones via a one-pot chloromethyleneiminium salt mediated three-component reaction

Simple enolizable ketones such as acetophenones and benzalacetones were treated with malononitrile under Vilsmeier-Haack reaction conditions to afford 2-chloronicotinonitriles. The reaction proceeds via a one-pot chloromethyleneiminium salt mediated three-component reaction followed by sequential cyclization and aromatization under Vilsmeier-Haack reaction conditions.     

Efficient catalyst-free synthesis of diversified bis (spirooxindoles) via one-pot,three-component reaction

A catalyst-free, one-pot synthesis of bis-spirooxindoles has been carried out by a three-component reaction of bis-isatins, malononitrile, and various cyclic enolizable carbonyl compounds in ethylene glycol at 100?°C. The protocol provides an easy and simple route for the synthesis of such complex compounds, in short reaction times and high yields. No chromatographic techniques have been employed for the purification of the compounds.     

A novel, one-pot and three-component synthesis of α-quinoxalinyl triphenylphosphoranes

The reactive 1:1 zwitterionic intermediate formed by the addition of triphenylphosphine to diaroylacetylenes was trapped with 1,2-benzenediamines to produce triphenylphosphorane intermediates. Intramolecular cyclization and subsequent oxidation of the intermediate afforded functionalized α-quinoxalinyl triphenylphosphoranes in good to excellent yields.     

A novel one-pot pyrrole synthesis via a coupling-isomerization-Stetter-Paal-Knorr sequence

[reaction: see text]. 1,2,3,5-tetrasubstituted pyrroles can be synthesized in good yields in a one-pot, three-step, four-component process by a coupling-isomerization-Stetter reaction-Paal-Knorr sequence of an electron-poor (hetero)aryl halide, a terminal propargyl alcohol, an aldehyde, and a primary amine. The structures of the 1,4-diketone 4f and the pyrrole 6b were additionally supported by X-ray structure analyses.     

A DMAP-catalyzed mild and efficient synthesis of 1,2-dihydroquinazolines via a one-pot three-component protocol

An efficient and simple method for the synthesis of 1,2-dihydroquinazolines catalyzed by 4-(N,N-dimethylamino)pyridine (DMAP) from readily available aromatic or heteroaromatic aldehydes, 2-aminobenzophenone, and ammonium acetate under mild conditions is described. The scope and limitations of the method are discussed.     

Palladium-catalyzed one-pot synthesis of highly substituted furans by a three-component annulation reaction

A new three-component cyclization-coupling reaction catalyzed by palladium was developed, producing polysubstituted furans in good yields from readily available substrates. The reaction conditions and the scope of the process were examined, and a possible mechanism is proposed.     

A novel one-pot three-component synthesis of 3-halofurans and sequential Suzuki coupling

A novel sequence of Sonogashira coupling and electrophilic addition to an ynone, with concomitant deprotection and cyclocondensation, opens a new one-pot synthesis of 3-halofurans; the method can be readily elaborated to a new sequential Sonogashira-addition-cyclocondensation-Suzuki reaction to furnish 2,3,5-trisubstituted furans in a one-pot fashion.     

Chemoselective synthesis of novel spiropyrano acenaphthylene derivatives via one-pot four-component reaction

An efficient one-pot four-component condensation reaction of acenaphthoquinone, pyrazolones or barbituric acid and 1,1-bis(methylthio)-2-nitroethene and alkylamines in ethanol for the synthesis of novel spiro[acenaphthylene-1,4′-pyrano[2,3-c]pyrazol]-2-one and spiro[acenaphthylene-1,5′-pyrano[2,3-d]pyrimidine]-trione is descibed. The significant features of this method include, readily available starting materials, operational simplicity, green solvent, catalyst-free condition, no column chromatographic purification and good to high yields.