A simple and efficient synthesis of 3,4-dihydropyrimidin-2-(1H)-ones via Biginelli reaction catalyzed by nanomagnetic-supported sulfonic acid

Nanomagnetic-supported sulfonic acid is found to be a new, powerful, and reusable heterogeneous catalyst for the rapid synthesis of 3,4-dihydropyrimidin-2-(1H)-ones under conventional heating and microwave irradiation. This is the first example of combination of magnetic iron nanoparticles and microwave technique for the multicomponent reaction. The optical behaviors of the 3,4-dihydropyrimidin-2-(1H)-ones have been investigated by UV–vis spectroscopy.     

Molybdenum-mediated synthesis of quinazolin-4(3H)-ones via cyclocarbonylation using microwave irradiation

A new, efficient and practical synthesis of quinazolin-4(3H)-ones is reported via molybdenum-mediated cyclocarbonylation using microwave irradiation. These methods allow access to a wide range of quinazolin-4(3H)-ones in reasonable yields without the need for gaseous carbon monoxide and palladium catalysts. A range of reactions illustrating the wide scope of this chemistry was carried out and all proceeded in reasonable yields.     

One-pot synthesis of quinolin-2-(1H)-ones via tandem Ugi-Knoevenagel condensations

A new application of the Ugi reaction in the synthesis of heterocyclic compounds is described. Substituted quinolin-2-(1H)-ones are formed in one-pot sequential Ugi four-component condensation and intramolecular Knoevenagel cyclization between o-acylanilines, aldehydes, malonic or tosylacetic acids and cyclohexyl isocyanide.     

A synthetic route to 11-(1H-pyrrol-1-yl)-11H-indeno[1,2-b]quinoxaline derivatives exploiting a three-component coupling strategy under microwave irradiation

11H-Indeno[1,2-b]quinoxalin-11-ones generated in situ from ninhydrin and various 1,2-phenylenediamines, catalysed by montmorillonite K10 under microwave irradiation, condense with 4-hydroxyproline to produce 11-(1H-pyrrol-1-yl)-11H-indeno[1,2-b]quinoxaline derivatives in good yields.     

A facile synthesis of (Z)-5-(substituted)-2-(methylthio)thiazol-4(5H)-one using microwave irradiation and conventional method

A new effective approach to the synthesis of some new (Z)-5-(substituted)-2-thioxothiazolidin-4-one 3a–l and (Z)-5-(substituted)-2-(methylthio)thiazol-4(5H)-one 5a–l is reported under microwave irradiation as well as conventional conditions.     

Green chemical multi-component one-pot synthesis of fluorinated 2,3-disubstituted quinazolin-4(3H)-ones under solvent-free conditions and their anti-fungal activity

A rapid one-pot solvent-free procedure has been developed for the synthesis of fluorinated 2,3-disubstituted quinazolin-4(3H)-ones by neat three-component cyclocondensation of anthranilic acid, phenyl acetyl chloride and substituted anilines under microwave irradiation. The experimental methodology and microwave conditions described here are well established, allowing significant rate enhancement and good yields compared to conventional reaction conditions. The reaction is generalized for o-, m- and p-substituted anilines with electron-donating and -withdrawing groups to give quinazolin-4(3H)-ones. Synthesized compounds have been screened for their anti-fungal activity.     

Rh(I)-catalyzed solvent-free ortho-alkylation of aromatic imines under microwave irradiation

The synthesis of ortho-alkylated ketones through a chelation-assisted Rh (I) catalyzed ortho-alkylation reaction of aromatic imines under microwave activated solvent-free conditions in monomode reactors was performed. These conditions have been also applied to hydroacylation and ortho-alkylation reactions with aldimines.     

Calcium acetate catalyzed synthesis of 4-arylidene-2-phenyl-5(4H)-oxazolones under solvent-free conditions

Eight 4-arylidene-2-phenyl-5(4H)-oxazolones (azlactones) have been prepared via Erlenmeyer synthesis from aromatic aldehydes and hippuric acid using calcium acetate under solvent-free conditions with microwave irradiation.     

TaBr5-catalyzed Biginelli reaction: one-pot synthesis of 3,4-dihydropyrimidin-2-(1H)-ones/thiones under solvent-free conditions

An efficient TaBr₅ (5-10 mol %)-catalyzed Biginelli reaction under solvent-free conditions for one-pot syntheses of 3,4-dihydropyrimidin-2-(1H)-ones (DHPMs) and their thione analogs is reported. The catalyst is stable at room temperature and employed under mild and environmentally friendly conditions.     

Ionic liquid phase organic synthesis (IoLiPOS) methodology applied to the three component preparation of 2-thioxo tetrahydropyrimidin-4-(1H)-ones under microwave dielectric heating

An ionic liquid phase organic synthesis (IoLiPOS) has been developed for the preparation of 2-thioxo tetrahydropyrimidin-4(1H)-ones. Treatment of the starting poly(ethyleneglycol)ionic liquid phases (PEG_n-ILPs) 1 with acryloyl chloride 2 afforded a serie of (PEG_n)-ILPs bound acrylate 3 in quantitative yields. Michael addition of aliphatic primary amines 5 to the PEG₁-ILPs 3(a,d) allowed the preparation of β-aminoesters 6 in high yields. Addition of alkyl isothiocyanates 7 to 6 gave the corresponding thioureido esters 8 in the third step. The final cyclization-cleavage under microwave/solventless strategy provides, under basic conditions, the expected 2-thioxo tetrahydropyrimidin-4(1H)-ones 9 in high purity after flash chromatography. According to the IoLiPOS methodology, the NMR method was used to establish loading of all the PEG-ionic liquid phases intermediates.     

A rapid synthesis of isoxazolo[5,4-d]pyrimidin-4（5H）-ones under microwave irradiation with solid acid catalysis in solvent-free conditions

A rapid and efficient method for the synthesis of isoxazolo[5,4-d]pyrimidin-4（5H）-ones has been developed through cyclocondensation of 5-aminoisoxazole-4-carboxamides with orthoesters under conventional heating and solvent-free microwave irradiation with solid acid catalysis. In comparison, the reactions are faster and the yields are higher under microwave irradiation.     

A new approach to the synthesis of 4-(N-aryl)carbamoylmethyl-4,5-dihydropyridazin-3(2H)-ones

Reaction of N-aryl substituted maleimides with aliphatic ketazines leads to the formation of 4,5-dihydropyridazin-3(2H)-ones in moderate yields. The reaction proceeds through 1,4-addition of an azine to the maleimide double bond, as confirmed by separation of the corresponding adducts in some cases, which are then converted into 4,5-dihydropyridazin-3(2H)-ones. In addition, the solid-state synthesis of 4,5-dihydropyridazin-3(2H)-ones is demonstrated for the first time.     

New three-component cyclocondensation reaction: microwave-assisted one-pot synthesis of 5-unsubstituted-3,4-dihydropyrimidin-2(1H)-ones under solvent-free conditions

Sixteen 5-unsubstituted-3,4-dihydropyrimidin-2(1H)-ones have been synthesized by microwave-assisted Biginelli reactions in a short and concise manner employing ZnI₂ as a catalyst under solvent-free conditions. All products were identified by IR, NMR, elemental analysis and HRMS. The advantages of this novel protocol include the excellent yield, operational simplicity, short time and the avoidance of the use of organic solvents and expensive catalysts.     

Ammonium chloride-catalyzed one-pot synthesis of 3,4-dihydropyrimidin-2-(1H)-ones under solvent-free conditions

Ammonium chloride as a very inexpensive and readily available reagent, and efficiently catalyzes one-pot, three component, Biginelli condensation reactions of aldehydes, 1,3-dicarbonyl compounds and urea or thiourea under solvent-free conditions to afford the corresponding 3,4-dihydropyrimidin-2-(1H)-ones in high yields at 100°C.     

A solvent-free synthesis of ethyl 3,5-diaryl-1H-pyrrole-2-carboxylates via triethylphosphite mediated reductive cyclization of ethyl 2-nitro-5-oxo-3,5-diarylpentanoates under microwave irradiation

Ethyl 3,5-diaryl-1H-pyrrole-2-carboxylates have been synthesized in good yields from ethyl 2-nitro-5-oxo-3,5-diarylpentanoates by treatment with triethylphosphite under microwave irradiation. The integrity of the mechanism proposed has been augmented by ³¹P NMR and EIMS experiments.     

Synthesis of pyrazino[1,2-a]benzimidazol-1(2H)ones via a microwave assisted Buchwald-Hartwig type reaction

A convenient synthesis of substituted pyrazino[1,2-a]benzimidazol-1(2H)ones starting from 3,5-dichloropyrazinones has been accomplished. Various 3-anilino-pyrazinones were easily converted to the desired tricyclic structures by applying a microwave assisted Buchwald-Hartwig type cyclization.     

New cycloaddition reaction between 4-arylidene-2-phenyl-5(4H)-1,3-oxazolones and benzyne; facile synthesis of 1,4(H)-benzoxazepine-2-ones and their N-phenyl derivatives

Reaction of 4-arylidene-2-phenyl-5(4H)-1,3-oxazolones with benzyne afforded predominantly, 3-arylidene-7-hydroxy-7-phenyl-1,4(H)-benzoxazepine-2-ones in addition to their N-phenyl derivatives. However, the reaction of the target oxazolones with an excess of benzyne gave only the N-phenyl derivatives of 1,4(H)-benzoxazepine-2-ones in good yields. The reaction mechanism describing product formation is also explained. Arylation of 1,4(H)-benzoxazepine-2-ones with benzyne proceeded successfully to give the N-phenyl products.     

CuO nanoparticles catalyzed simple and efficient synthesis of 2,3-dihydroquinazolin-4(1H)-ones and quinazolin-4(3H)-ones under ultrasound irradiation in aqueous ethanol under ultrasound irradiation in aqueous ethanol

A CuO nanoparticle-catalyzed one-pot process has engineered for the preparation of diverse quinazolinones from the readily available isatoic anhydride, aldehydes and amine or ammonium. For amine substrates the reactions afford 2,3-dihydroquinazolin-4(1H)-ones in aqueous ethanol promoted by ultrasound irradiation. However, the ammonium substrates undergo intramolecular electron transfer and rearrangement yielding quinazolin-4(3H)-ones. The catalyst is recyclable four times without loss of substantial activity. Other remarkable features include the wide range of functional group tolerance (46 quinazolinones are synthesized and 9 of them are reported firstly), and providing moderate to excellent yield of the products under mild conditions.     

Asymmetric 1,3-dipolar reactions of 3-sulfinylfuran-2(5H)-ones with 11H-dibenzo[b,e]azepine 5-oxide. Synthesis of pyrroloazepines via isoxazoloazepines

The addition of morphanthridine N-oxide (1) to homochiral 3-p-tolylsulfinylfuran-2(5H)-ones (2a and 2b) under mild conditions affords furoisoxazoloazepines (3a and 3b) in high yields and with complete regioselectivity. The π-facial and endo-selectivities are also complete from 2a, which yields anti-3a-endo as the only diastereoisomer, whereas cycloreversion determines that the anti-3b-endo adduct can be almost exclusively isolated from 2b. Proper manipulation of the furoisoxazoloazepines allows the synthesis of the optically pure isoxazoloazepines and pyrroloazepines.     

Sulfamic acid: a novel and efficient catalyst for the synthesis of aryl-14H-dibenzo[a.j]xanthenes under conventional heating and microwave irradiation

A simple and convenient procedure for the synthesis of aryl-14H-dibenzo[a.j]xanthenes is described through a one-pot condensation of β-naphthol with aryl aldehydes in the presence of sulfamic acid as the catalyst in a solvent-free media using both conventional heating and microwave irradiation.