Synthesis of new substituted cylopentenone derivatives via a one-pot three-component reaction between arylglyoxals,acetylacetone, and amines in aqueous media

An efficient one-pot method for the synthesis of new substituted cylopentenone derivatives is described via reaction of arylglyoxals and acetylacetone with aliphatic amines. This reaction was carried out in aqueous media in the absence of any catalyst or promoter to produce substituted cylopentenone in high yield.     

Synthesis of pyrimido[6,1-a]isoquinolines via a one-pot, four-component reaction

An efficient one-pot synthesis of pyrimido[6,1-a]isoquinoline-1-carboxylate derivatives is described. This involves the four-component reaction between primary amines, alkyl acetoacetates, isoquinoline and trichloromethylchloroformate (diphosgene) under mild conditions at ambient temperature.     

Synthesis of novel annulated uracils via domino Knoevenagel-hetero-Diels-Alder reaction in aqueous media

An efficient synthesis of tetracyclic uracil derivatives (polycyclic pyrans) is achieved via domino Knoevenagel-hetero-Diels-Alder reactions of O-propargylated salicylaldehyde derivatives with 1,3-dimethylbarbituric acid in water as solvent in the presence of CuI. The products are formed in good yields.     

Multicatalytic synthesis of 1,2-dihydroisoquinolin-1-ylphosphonates via a tandem four-component reaction

A tandem four-component reaction of 2-bromobenzaldehyde, alkyne, amine, and diethyl phosphite catalyzed by the combination of palladium and copper salts provides a facile and efficient route to 1,2-dihydroisoquinolin-1-ylphosphonate. A cascade Sonogashira-intramolecular cyclization-nucleophilic addition may be involved in the reaction process.     

Synthesis of dialkyl 5-(aryl)-1-phenyl-1H-prazole-3,4-dicarboxylates via a one-pot and four-component reaction

A number of new dialkyl 5-(aryl)-1-phenyl-1H-prazole-3,4-dicarboxylate derivatives have been prepared regiospecifically in moderate to good yield from the cyclocondensation reaction of dialkyl (E)-2-(dialkoxyphosphoryl)-3-(aroyl)-2-butenedioate, derived from the reaction between trimethyl phosphite, an acetylenic ester, and an aroyl chloride, with phenylhydrazine. The reaction is four-component and is carried out under reflux conditions in dry toluene.     

Iodine-catalyzed synthesis of 2-arylpyrazolo[5,1-b]quinazolin-9(3H)-one derivatives in ionic liquids via domino reaction

The domino reaction of (E)-2-amino-N′-(1-arylethylidene)benzohydrazide and triethyl orthoformate in ionic liquids catalyzed by 10 mol % iodine gave 3a,4-dihydro-2-arylpyrazolo[5,1-b]quinazolin-9(3H)-one derivatives unexpectedly. In the presence of K₂S₂O₈, it could be oxidized to aromatized products in good yields.     

Nanosized magnesium oxide as a highly effective heterogeneous base catalyst for the rapid synthesis of pyranopyrazoles via a tandem four-component reaction

A four-component reaction of hydrazine hydrate or phenyl hydrazine, ethyl 3-alkyl-3-oxo propanoate, aldehydes and malononitrile has been achieved in the presence of nanosized magnesium oxide as a highly effective heterogeneous base catalyst to produce of 6-amino-3-alkyl-4-aryl-5-cyano-1,4-dihydropyrano[2,3-c]pyrazole derivatives in excellent yields and in a short experimental time. This method is simple and rapid for focusing a pyrano ring with a pyrazole ring.     

Heterogenized tungsten complex: an efficient and high yielding catalyst for the synthesis of structurally diverse tetra substituted pyrrole derivatives via four-component assembly

An efficient, high yielding, and expeditious method has been developed for the synthesis of diversity oriented pyrrole derivatives via a four component, one-pot cyclocondensation reaction of amines, aldehydes, α-methylene ketones, and nitroalkanes using silica supported tungstic acid as a heterogeneous catalyst for the first time. The scope of the domino reaction is successfully explored toward synthesis of highly aryl-substituted pyrroles. The reaction was conveniently promoted by silica supported tungstic acid and the catalyst could be recovered easily after the reaction and reused without any loss of its catalytic activity. The advantageous features of this methodology are high atom-economy, operational simplicity, shorter reaction time, convergence, and facile automation.     

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.     

Direct-type catalytic three-component Mannich reaction in aqueous media

Bismuth triflate catalyzed direct-type Mannich reaction of cyclohexanone, aromatic aldehyde, and aromatic amine proceeded smoothly in water to afford the corresponding β-amino ketone with very good yield and moderate to good anti selectivity.     

A new domino Knoevenagel-hetero-Diels-Alder reaction: an efficient catalyst-free synthesis of novel thiochromone-annulated thiopyranocoumarin derivatives in aqueous medium

An efficient catalyst-free synthesis of novel pentacyclic thiochromone-annulated thiopyranocoumarin derivatives is achieved via domino Knoevenagel-hetero-Diels-Alder reaction of 4-hydroxy dithiocoumarin and O-acrylated salicylaldehyde derivatives in H₂O as solvent. The products are formed in good yields with high regio- and stereo-selectivity.     

Lead-promoted Barbier-type reaction of aldehydes with propargyl bromides in aqueous media

This paper reports that the reaction of the propargyl bromides with aldehydes promoted by powdered lead in aqueous media.The selectivity and possible mechanism of these reactions are discussed.The yields of products for reaction of propargyl bromide are 31~71%.The ratios of al-lenyl alcohol and homopropargyl alcohol are 1:1.5 to 1:3.The product for reaction of phenyl propargyl bromide is allenyl alcohol and the yields are 52~84%.     

Chemo- and diastereoselective synthesis of new oxa[3.3.3]propellane via a domino cascade four-component reaction based on diketene

A highly convergent, eco-friendly and straightforward synthesis of new O-fused heterocycles, functionalized indeno[1,2-b]furan derivatives was successfully accomplished through a one-pot four-component cascade reaction involving, ninhydrin, malononitrile, diketene and various primary amines in the presence of a catalytic quantity of triethylamine in ethanol at ambient temperature, in one pot fashion. This new efficient cascade reaction generates two rings by the simultaneous construction of C-N (one), C-O (two) and C-C (two) multiple bonds, presumably through a sequence of Knoevenagel reaction/Michael addition/intramolecular O-cyclization and imine-enamine/keto-enol tautomerization. The merits of this protocol are highlighted as utilization of inexpensive commercially accessible starting materials, operational simplicity, atom economy, clean reaction profile, simple work-up procedure being conducted at ambient temperature in relatively short reaction times, preventing chromatographic purification, giving excellent yields, and tolerance to a wide variety of functional groups.     

Ugi-type four-component reaction for a novel synthesis of 5-oxo-perhydrofuro[3,2-b]pyran carboxylate derivatives

The four-component coupling (4CC) of sugar hydroxyaldehyde, Meldrum’s acid, isocyanide, and a secondary alcohol in dichloromethane has been accomplished at room temperature in a highly stereoselective manner to produce a novel class of carbohydrate derivatives, 5-oxo-perhydrofuro[3,2-b]pyrans in good yields with trans-selectivity. The stereochemistry of the products was assigned by various NMR experiments.     

Synthesis of Polysubstituted 1,4-Dihydropyridines via Four-component Reactions of Arylamine,Acetylenedicarboxylate, Aromatic Aldehyde and Ethyl Acetoacetate

An efficient synthetic protocol for the 1,4-diaryl-1,4-dihydropyridines was developed via the domino four-component reaction of arylamine, acetylenedicarboxylate, aromatic aldehyde and ethyl acetoacetate. The reaction mechanism involves the formation of β-enamino ester and its sequential Michael addition to arylidene acetoacetate.     

Synthesis of new type of Betti bases via three-component reaction of β-naphthol,cyclic amines and isatins

This work provided the first example of incorporating the oxindole moiety into the Betti bases. The new type of Betti bases were conveniently synthesized in good yields from the three-component reaction of β-naphthol, isatins and cyclic amines, such as piperidine ormorpholine, in methylene dichloride without any other catalyst.     

Synthesis of fully substituted pyrazolo[3,4-b]pyridine-5-carboxamide derivatives via a one-pot four-component reaction

A one-pot four-component reaction of an aliphatic or aromatic amine, diketene, an aromatic aldehyde and 1,3-diphenyl-1H-pyrazol-5-amine in the presence of p-toluenesulfonic acid as a catalyst has been developed. In this reaction, a new class of fully substituted pyrazolo[3,4-b]pyridine-5-carboxamide derivatives is produced under mild reaction conditions and in good yields at ambient temperature.     

An efficient and recoverable palladium organocatalyst for Suzuki reaction in aqueous media

Meso‐tetrakis[4‐(methoxycarbonyl)phenyl]porphyrinatopalladium(II) as a palladium organocatalyst was synthesized and then used in aqueous media as a heterogeneous organocatalyst in Suzuki reaction. The prepared organocatalyst was characterized using UV–visible, infrared and NMR spectroscopies. It was found to be an efficient catalyst for Suzuki coupling reaction between phenylboronic acid and a broad range of aryl halides. Mild reaction conditions, water solvent as green media, and easy catalyst separation and reusability are the advantages of the presented method.     

Synthesis of flavonoid 2-deoxyglucosides via the Mitsunobu reaction

The Mitsunobu reaction of flavonoids and 3,4,6-tri-O-acetyl-2-deoxy-d-glucopyranose or 3,4,6-tri-O-benzyl-2-deoxy-d-glucopyranose is a very effective method for the stereoselective synthesis of flavonoid 2-deoxyglucosides. Since there is no C2 substituent on the sugar moieties, the observed α- or β-stereoselectivity was mainly controlled by the (acetyl or benzyl) protecting groups. Possible mechanistic insights are offered to explain the dual stereoselectivity.     

New domino reaction. One pot synthesis of 4,7-dihydroxythioaurone derivatives from benzaldehydes and 4-acetyl-2-oxo-benz[1,3]oxathiole

A convenient synthesis of 4,7-dihydroxythioaurone derivatives by a one pot reaction of benzaldehydes with 4-acetyl-2-oxo-benz[1,3]oxathioles and piperidine acetate in DMSO is described. The structures of the compounds, including double bond geometry were proved unequivocally by NMR methods. The thioaurone ring system seems to be formed by three consecutive reactions: opening of the oxathiolone ring with piperidine, oxidation of the formed mercapto group with DMSO or/and air to disulfide, and condensation with aldehyde.