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A new spiro derivative of dihydro-1,2,3-triazolo[1,5-a]pyrimidine - 5'-amino-6'-cyano-4'H-spiro[cyclohexane-1,7'-[1,2,3]triazolo[1,5-a]-pyrimidine]-3'-carboxamide - was prepared by three-component reaction of 5-amino-1,2,3-triazole-4-carboxamide with malononitrile and cyclohexanone; the structure of product was established by X-ray analysis. Microwave activation and conventional heating showed the formation of single product and the same direction of heterocyclization. Available literature data concerning similar reactions using 3-amino-1,2,4-triazole or 2-aminobenzimidazole were reinvestigated experimentally with consideration of alternative structures; structures of products were studied by NMR including NOE experiments. [ABSTRACT FROM AUTHOR]

By acylation of substituted 2-aminoarylpyrimidines with 5-phenyl(p-tolyl)isoxazole- and 4,5-dichloroisothiazole-3-carbonyl chlorides new amides of pyrimidine series were obtained. [ABSTRACT FROM AUTHOR]

5-Substituted 2,6-dimethylpyrimidin-4(3H)-ones were synthesized, and their structure was proved by X-ray analysis. Their reactions with aromatic aldehydes regioselectively afforded (Z)-2-(2-arylethenyl)- pyrimidin-4(3H)-ones whose structure was determined by one- and two-dimensional (NOESY) 1H NMR and X-ray analysis. [ABSTRACT FROM AUTHOR]

2-(Allylamino)pyrido[3,2-d]pyrimidin-4(3H)-one was converted to linearly fused dihydroimidazo- [1,2-a]pyrido[3,2-d]pyrimidine on heating in polyphosphoric acid, whereas its reactions with molecular iodine and chlorosulfanylarenes afforded mainly angularly fused analogs. 2-(Cinnamylamino)pyrido[3,2-d]pyrimidin- 4(3H)-one reacted with polyphosphoric acid and chlorosulfanylarenes to give linear pyrido[3,2-d]pyrimido-[1,2-a]pyrimidinones, and its iodocyclization led to the formation of angularly fused derivative. [ABSTRACT FROM AUTHOR]

The selectivity of the domino reaction of the (het)aryl azides, containing the carbonyl center in the ortho position to the azido group, with malonodinitrile dimer was studied. It has been shown that in the case of aromatic azides bearing a carboxy or nitrile function in the ortho position, the reaction occurred with the formation of exclusively [1,2,3]triazolo[1,5-a]pyrimidine instead of [1,2,3]triazolo[4,5-b]pyridine system. Thus, new [1,2,3]triazolo[1,5-a]quinazolines, thieno[2,3-e][1,2,3]triazolo[1,5-a]pyrimidine, and thieno[3,2-e][1,2,3]triazolo[1,5-a]-pyrimidines, having polyfunctional 1-amino-2,2-dicyanovinyl fragment, were prepared in short time in high yields. [ABSTRACT FROM AUTHOR]

This paper reports an efficient method for the synthesis of pyrano[2,3- d]pyrimidine derivatives via a one-pot four-component reaction between N, N-dimethyl barbituric acid, piperidine, aldehydes and 4-hydroxycoumarin. Mild reaction condition, easy purification and good yields are the main feature of this synthesis. [ABSTRACT FROM AUTHOR]

In this work, 4,4′-(butane-1,4-diyl)bis(1-sulfo-1,4-diazabicyclo[2.2.2]octane-1,4-diium)tetrachloride (NS-C(DABCO-SOH)·4Cl), a newly reported nano-sized Brönsted acid catalyst is used for the effective synthesis of pyrimido[4,5- d]pyrimidinones and pyrano[2,3- d]pyrimidinones derivatives. The products were formed under mild and environmentally friendly conditions in excellent yields over very short reaction times. Using green solvent and simple methodologies, no side reactions and use of inexpensive catalyst with lower loading are other advantages of this work. [ABSTRACT FROM AUTHOR]

The interaction of available 2-methylsulfonyl-3-ethoxyacrylonitrile with amidine, their analogs, and aminoazoles containing amidine fragment, yielding earlier unknown 4-amino-5-methylsulfonylpyrimidines and their fused derivatives has been studied. [ABSTRACT FROM AUTHOR]

A trifluoroacetic acid-mediated cascade reaction involving nucleophilic substitution and Smiles rearrangement is described. The reaction of hydroxydihydrodiazepines with primary amines led to amino-substituted dihydrodiazepines, which readily underwent Smiles rearrangement to give pyrrolo[1,2- f]pteridine derivatives. [ABSTRACT FROM AUTHOR]

Series of novel substituted thioxopyrimidine and thiazolo[3,2- a]pyrimidine compounds that combine various heteroaryl rings have been synthesized via Biginelli one-pot three-component reaction and elucidated with chemical and spectral analysis. Several products were tested for their antimicrobial properties. [ABSTRACT FROM AUTHOR]

Reaction of substituted 2(4)-hydrazinopyrimidines with 3-aryl-1-phenyl-2-propen-1-ones in the presence of a base results prevailingly in 5-aryl-1-[pyrimidin-2(4)-yl]-3-phenyl-4,5-dihydro-1 H-pyrazoles. The fragmentation path of these compounds under positive electrospray ionization consists in simultaneous decomposition of their heterocyclic fragments. [ABSTRACT FROM AUTHOR]

The article discusses a study which investigated the reactions of the dipolarophile compounds, 5-(arylmethylidene)-2,4,6-pyrimidine-2,4,6(1H,3H,5H)-triones, with p-phenacyl- and p-acetonylisoquinolinium bromides which are precursors of azomethine ylides. Topics discussed include the generation of active azomethine ylides as a result of the treatment of N-onion salts with sodium hydroxide, the reactions of the reagents, and the molecular structure of the compounds.

In this work, succinimidinium hydrogensulfate ([H-Suc]HSO), a newly reported Brönsted acidic ionic liquids is used as an efficient, homogeneous and reusable catalyst for the synthesis of 5-arylidenepyrimidine-2,4,6(1 H,3 H,5 H)-trione and pyrano[2,3-d]-pyrimidine dione derivatives. The products were formed in excellent yields over short reaction times and the catalyst can be reused several times without any appreciable loss in its activity. [ABSTRACT FROM AUTHOR]

By condensation of 2-aryl-substituted pyrimidin-5-ylpropanoic acids with 1,2-ethanediamine and 1,2-benzenediamine in polyphosphoric acid new derivatives of heterocyclic systems were synthesized: imidazo- and benzo[4',5']imidazo[1',2':1,6]pyrido[2,3- d]pyrimidines. Unlike that the reaction of substituted 2-mercaptopyrimidin-5-ylpropanoic acid with 1,2-benzenediamine in polyphosphoric acid in the presence of equimolar amount of ZnCl proceeds by a tandem mechanism with the formation of 4-methyl-5,6-dihydrobenzo[4',5']imidazo[1',2':1,6]pyrido[2,3- d]pyrimidine-2-thiol and the corresponding disulfide. [ABSTRACT FROM AUTHOR]

A mild and efficient method has been used for the synthesis of ethyl 4-(3-hydroxphenyl)-6-methyl-2-thioxo-1,3-dihydroprimidine-5-carboxylate (monastrol) ( 2), via Biginelli reaction. Alkylation of 2 with the fluorescent coumarin 3 afforded the new thioether analog 4. Similarly, ethyl 4-(6,8-dichloro-2-oxo-2 H-chromen-3-yl)-6-methyl-2-thioxo-1,2,3,4-tetrahydro-pyrimidine-5-carboxylate ( 6) was prepared. The synthesized compounds are fluorescent active and show wavelength of maximum absorption (λ) in UV or visible region in MeOH at room temperature. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Three-component reaction of methyl benzoylpyruvate, aromatic aldehyde, and urea in methanol in the presence of sodium bisulfate stops at the stage of the formation of nondehydrated product with a methylated tertiary hydroxy group and results in methyl 6-aryl-5-benzoyl-4-methoxy-2-oxohexahydropyrimidine-4-carboxylates. [ABSTRACT FROM AUTHOR]

Substituted 2-spiropyrimidin-4-ones are formylated at room temperature under the conditions of the Vilsmeier-Haack reaction. When cautiously heated they undergo electrophilic rearrangement. [ABSTRACT FROM AUTHOR]

This minireview provides the first presentation and analysis of literature data published over recent years on the synthesis and chemical reactivity of 1,2,5-oxadiazole N-oxides (furoxans) fused with other heterocycles (pyridine, pyridazine, pyrimidine, pyrazine, and 1,4-dithiane). [ABSTRACT FROM AUTHOR]

A new approach to prepare 2-chloroacetamides has been developed, based on the reaction of chloroacetyl chloride with excess of secondary amines. Alkylation of 6-methyl-1-(thiethan-3-yl)pyrimidine-2,4(1 H,3 H)-dione with the synthesized 2-chloroacetamides in the presence of potassium carbonate has afforded N-acetamido-substituted 6-methyl-1-(thiethan-3-yl)pyrimidine-2,4(1 H,3 H)-diones. [ABSTRACT FROM AUTHOR]

Vitamin traffic, the production of organic growth factors by some microbial community members and their use by other taxa, is being scrutinized as a potential explanation for the variation and highly connected behavior observed in ocean plankton by community network analysis. Thiamin (vitamin B1), a cofactor in many essential biochemical reactions that modify carbon-carbon bonds of organic compounds, is distributed in complex patterns at subpicomolar concentrations in the marine surface layer (0-300 m). Sequenced genomes from organisms belonging to the abundant and ubiquitous SAR11 clade of marine chemoheterotrophic bacteria contain genes coding for a complete thiamin biosynthetic pathway, except for thiC, encoding the 4-amino-5-hydroxymethyl-2-methylpyrimidine (HMP) synthase, which is required for de novo synthesis of thiamin's pyrimidine moiety. Here we demonstrate that the SAR11 isolate 'Candidatus Pelagibacter ubique', strain HTCC1062, is auxotrophic for the thiamin precursor HMP, and cannot use exogenous thiamin for growth. In culture, strain HTCC1062 required 0.7 zeptomoles per cell (ca. 400 HMP molecules per cell). Measurements of dissolved HMP in the Sargasso Sea surface layer showed that HMP ranged from undetectable (detection limit: 2.4 pM) to 35.7 pM, with maximum concentrations coincident with the deep chlorophyll maximum. In culture, some marine cyanobacteria, microalgae and bacteria exuded HMP, and in the Western Sargasso Sea, HMP profiles changed between the morning and evening, suggesting a dynamic biological flux from producers to consumers. [ABSTRACT FROM AUTHOR]

Reaction of N-arylamides of acetoacetic acid with aromatic aldehyde and 3-amino-1,2,4-triazole derivatives has resulted in N,7-diaryl-5-methyl-4,7-dihydro-1,2,4-triazolo[1,5- a]pyrimidine-6-carboxamides. [ABSTRACT FROM AUTHOR]

Benzoylacetonitriles are easily available and have high chemical reactivity due to the presence of three active moieties; nitrile, carbonyl, and active methylene functions. This review article represents a survey covering the synthetic strategies leading to five six-membered heterocycles; pyrans, pyridazines, pyrimidines, pyrazines, and triazine compounds; utilizing benzoylacetonitriles as starting precursor since 1985. The reactions are subdivided into groups that cover the synthetic methods of these heterocycles. [ABSTRACT FROM AUTHOR]

A procedure for the preparation of 6-methyl-3,4-dihydropyrimidin-2(1 H)-ones involving deacylation of 5-acetyl-6-methyl-3,4-dihydropyrimidin-2(1 H)-ones in MeOH-KOH medium is developed. We have shown that the obtained compounds readily undergo reaction with chalcones in MeOH-MeONa with the formation of derivatives of 4,5,7-triaryl-3,4,5,6-tetrahydroquinazolin-2(1 H)-one. [ABSTRACT FROM AUTHOR]

Brønsted acidic ionic liquids, namely 2-pyrrolidonium hydrogensulfate, N-methyl-2-pyrrolidonium hydrogensulfate, N-methyl-2-pyrrolidonium dihydrogenphosphate, (4-sulfobutyl)tris(4-sulfophenyl)phosphonium hydrogensulfate, triphenyl(propyl-3-sulfonyl)phosphonium toluenesulfonate, l-prolinium sulfate, and l-prolinium nitrate, catalyzed efficient one-pot pseudo-four-component reaction of salicylaldehydes, malononitrile, and secondary amine for preparation of chromeno[2,3- d]pyrimidines under solvent-free conditions at room temperature. The catalysts show environmentally benign character and can be easily prepared, stored, and recovered without obvious significant loss of activity. [ABSTRACT FROM AUTHOR]

Reaction of 4-cyano-1,3-oxazole-5-sulfonyl chlorides with amidines results in new 7-amino-1,3-oxazolo[5,4- d]pyrimidines. Their structure was confirmed by spectral methods and X-ray diffraction analysis. [ABSTRACT FROM AUTHOR]

A simple and efficient approach towards one-step synthesis of 2-amino-5-cyano-4-hydroxy-6-aryl pyrimidines has been developed. It is based on three-component condensation of aliphatic, aromatic or heterocyclic aldehydes, ethyl cyanoacetate and guanidinium carbonate in the presence of amino-functionalized SBA-15 catalyst in ethanol. In this chemical process, the tautomeric interconversion of pyrimidine derivatives has been observed. This efficient technique has the advantage to give 2-amino-pyrimidine derivatives using a heterogeneous catalyst in high yields, to be completed in short reaction times and to offer a simple product isolation procedure. [ABSTRACT FROM AUTHOR]

The reaction of 6-methyl-2-(2-oxo-2-phenylethylidene)-2,3-dihydropyrimidin-4(1 H)-one and of its nitrosation product with hydroxylamine stops at the stage of forming the corresponding oximes. The reaction of 6-methyl-2-(2-oxo-2-phenylethylidene)-2,3-dihydropyrimidin-4(1 H)-one with hydrazine yields a mixture of 3-amino-5-phenylpyrazole and 3-methyl-2-pyrazolin-5-one in 71 and 62% yields, respectively. The ketoxime is used in the synthesis of a series of imidazole N(3)-oxides substituted at the 1, 4, and 5 positions of the imidazole ring. [ABSTRACT FROM AUTHOR]

Reactions of 4,6-dihydrazino-5-nitro- and 2-methylthio-4-hydrazino-6-chloro-5-( p-alkoxybenzyl)pyrimidines with carbonyl compounds and aryl- and cyclohexylisothiocyanates were studied. The influence of the products on DNA methylation and their in vitro antitumor properties were studied. [ABSTRACT FROM AUTHOR]

Regioselectivity was examined of reactions between nine 3(5)-aminopyrazoles and 2-acetylcyclopentanone and 2-acetylcyclohexanone under various conditions. A series of cyclopenta[ e]pyrazolo-[1,5-a]pyrimidines was obtained. The highest regioselectivity of the reaction was observed in alcohol at 20°C in the presence of a catalytic quantity of trifl uoroacetic acid. The regiostructure of compounds was established by H and C NMR spectroscopy. [ABSTRACT FROM AUTHOR]

Triazolo[1′,5′:1,2]pyrimido[4,5- d]azocines were synthesized by the tandem expansion of the tetrahydropyridine ring in tetrahydropyridotriazolopyrimidines by the action of activated alkynes. Under these conditions, triazolopyridopyrimidines benzylated at the nitrogen atom of the pyrimidine moiety undergo the Hofmann cleavage of the tetrahydropyridine ring to form 5-vinyltriazolo[1,5- a]pyrimidines. [ABSTRACT FROM AUTHOR]

Information relating to the synthesis of tetrahydropyrimidin-2(1 H)-ones(thiones), annelated at the N(1)-C(6) bond, by cascade cyclization of substituted N-(3-oxoalkyl)ureas and thioureas is classified. The general relationships of this process are presented. [ABSTRACT FROM AUTHOR]

6-Allylamino-1-R-4,5-dihydro-1 H-pyrazolo[3,4- d]pyrimidines treated with iodine in the presence of potassium carbonate are converted into 6-allylamino-1-R-1 H-pyrazolo[3,4- d]pyrimidines that at further reaction with iodine undergo the cyclization into 6-iodomethyl-1-R-1,6,7,8-tetrahydroimidazo [1,2- a]pyrazolo[3,4- d]-pyrimidin-5-ium iodide of a linear structure. In the absence of potassium carbonate alongside the mentioned linear products 8-iodo-methyl-1-R-1,4,5,6,7,8-hexahydroimidazo[1,2- a]pyrazolo[4,3- e] pyrimidin-9-ium iodides of an angular structure have been obtained. [ABSTRACT FROM AUTHOR]

Three-component reaction of N-methyl- or N,N-diethyl-3-oxobutanamide with aromatic aldehydes and tetrazol-5-amine monohydrate gave the corresponding N-substituted 7-aryl-5-methyl-4,7-dihydrotetrazolo-[1,5- a]pyrimidine-6-carboxamides. [ABSTRACT FROM AUTHOR]

A number of 2-(anthracen-9-yl)-substituted imidazolidines and hexahydropyrimidines were synthesized by reaction of N,N′-bis[aryl(hetaryl)methyl]ethylene-1,2-diamines and N,N′-bis[aryl(hetaryl)methyl]-propane-1,3-diamines with anthracene-9-carbaldehyde. The obtained compounds showed chemosensor activity toward Cd, Cu, and Hg ions. [ABSTRACT FROM AUTHOR]

A reaction of 2-diaminomethylidenedimedone with aryl isocyanates leads to the formation of the corresponding ureas, which upon the action of sodium methoxide cyclize to 4-amino-7,8-dihydroquinazoline-2,5(1 H,6 H)-dione derivatives. The latter react with aryl isocyanates following the similar scheme to furnish 1,6-diaryl-8,8-dimethyl-7,8-dihydro-1 H-pyrimido-[4,5,6- de]quinazoline-2,5(3 H,6 H)-diones, new tricyclic compounds containing pyrimidopyrimidine fragment. [ABSTRACT FROM AUTHOR]

Methyl 1-aryl-3-aroyl-4,5-dioxo-4,5-dihydro-1 H-pyrrole-2-carboxylates reacted with 3-methyl-4-phenyl-1 H-pyrazol-5-amine to give methyl 7-arylcarbamoyl-6-aroyl-2-methyl-3-phenylpyrazolo[1,5- a]-pyrimidine-5-carboxylates. The molecular and crystalline structures of methyl 6-benzoyl-7-(4-chlorophenylcarbamoyl)-2-methyl-3-phenylpyrazolo[1,5- a]pyrimidine-5-carboxylate were studied by X-ray analysis. [ABSTRACT FROM AUTHOR]

Substituted o- and p-nitroanilines and m-benzylaminoanilines in the reaction with cyanamide failed to yield the corresponding arylguanidines, and in the presence of 3-dimethylamino-1-(3-pyridyl)-2-propen-1-one formed 4-pyridyl-substituted pyrimidin-2-ylcyanamides and 2-amino-pyrimidines. [ABSTRACT FROM AUTHOR]

Electrochemical and optical properties of cyclometallated Rh(III) and Pd(II) complexes based on phenyl-substituted pyrazole, pyridine, and pyrimidine with ethylenediamine, 2,2′-bipyridine, and 1,10-phenanthroline chelating ligands were investigated. One-electron reduction waves of the complexes were assigned to ligand-centered processes of electron transfer on π* orbitals of heterocyclic chelating and cyclometallated ligands, whereas irreversible oxidation waves, to the processes involving a mixed phenyl-metal π/d orbital. The long-wave absorption band results from by the spin-allowed optical transition between π/d-HOMO and a π* orbital of a cyclometallated ligand. The character of the optical transition responsible for low-temperature (77 K) phosphorescence of the complexes is defined by the ratio of the energy gap between π* orbitals of chelating and cyclometallated ligands and by the energy of the singlet-triplet splitting of electron-excited states. [ABSTRACT FROM AUTHOR]

5-Acylamino-4-amino-6-arylsulfanylpyrimidines were formed by the reaction 3-arylsulfanyl-2-acylami- no-3-chloroacrylonitriles with benzamidine. The products were converted into new derivatives of 6-aryl- sulfanyl-substituted purine bases by treatment with polyphosphoric acid. [ABSTRACT FROM AUTHOR]

Fusion of methyl 4-(2-thienyl)-2,4-dioxobutanoate with 1 H-tetrazol-5-amine monohydrate and aromatic aldehyde gave methyl 7-aryl-6-(2-thenoyl)-4,7-dihydrotetrazolo[1,5- a]pyrimidine-5-carboxylates which reacted with an equimolar amount of hydrazine hydrate at 180-190°C under solvent-free conditions to produce 9-aryl-8-(2-thienyl)-4,9-dihydrotetrazolo[1′,5′: 1,2]pyrimido[4,5- d]pyridazin-5(6 H)-ones. [ABSTRACT FROM AUTHOR]

A simple and efficient method has been developed for the synthesis of series of 4-aryl-1,3,4,5-tetrahydro-2 H-indeno[1,2- d]pyrimidine-2-thiones through Biginelli's one-pot multicomponent condensation reaction via microwave irradiations. Then, these thiones were converted to their S-alkylated/aralkylated derivatives. The prepared heterocyclic products were structurally confirmed by analytical and spectral data and evaluated for their antibacterial activities. The results showed that this skeletal framework exhibited marked potency as antibacterial agents. The compound 2-(Ethylthio)-4-(4-Hydroxy-3-methoxyphenyl)-4,5-dihydro-1 H-indeno[1,2- d]pyrimidines 4b have shown antibacterial activity towards all the seven clinical isolates used. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

A new type of intramolecular cyclization of 1,5-bis[2-( E-3-oxo-3-phenylprop-1-enyl)-phenoxy]-3-oxapentane with 3-aminotriazole promoted by potassium ions was discovered. A cascade mechanism for the formation of crownophane with 4,7-dihydro[1,2,4]triazolo[1,5- a]-pyrimidine fragment was suggested. Effects of oligooxyethylene fragment of the chalcone podand and acid-base catalysis on the selectivity of the cyclocondensation processes and degree of oxidation of triazolopyrimidine fragments were studied. The product structures were confirmed by IR, H and C NMR spectroscopy and X-ray diffraction study. [ABSTRACT FROM AUTHOR]

The alkylation of 4-polyfluoroalkylpyrimidin-2-ones with iodomethane, 4-bromobutyl acetate, and epichlorhydrin occurs regiospecifically to form O-regioisomers. [ABSTRACT FROM AUTHOR]

Condensations of aromatic carbo- and heterocyclic ketones and aldehydes in methanol gave new chalcones containing carbazole fragments, 1,3-diaryl(9-R-9 H-carbazol-3-yl)prop-2-en-1-ones. Some of the synthesized chalcones reacted with guanidine sulfate to produce 2-amino-4,6-diarylpyrimidines that are promising materials for the design of light emitting diodes. Study on electrochemical polymerization of both chalcones and pyrimidines derived therefrom showed that almost all the examined substrates give rise to stable colored conjugated polymer films on the surface of working electrode under conditions of cyclic voltammetry. [ABSTRACT FROM AUTHOR]

The antiradical properties of a number of uracil derivatives are studied in initiated 1,4-dioxane oxidation as a model reaction. The antioxidant activity of the uracil derivatives as inhibitors is estimated. The antiradical activity of the compounds is quantitatively characterized in terms of the effective rate constant of inhibition, fk. [ABSTRACT FROM AUTHOR]

We present herein a new and efficient method for synthesis of bis-pyrazol pyrimidine derivatives by N-alkylation using a microwave-assisted synthetic process. Two new compounds, N-(4,6-bis(3,5-dimethyl-1 H-pyrazol-1-yl)methyl nicotinonitrile and 2,6-bis(3,5-dimethyl-1 H-pyrazol-1-yl)-4-methyl nicotinonitrile, were synthesized by the N-alkylation reaction. The novel compounds were characterized by Fourier transform infrared spectrometry, ultraviolet spectroscopy, elemental analysis, and nuclear magnetic resonance spectroscopy, etc. The microwave-assisted procedures have noteworthy advantages in terms of thermal efficiency over those carried out by conventional heating methods. Graphical abstract: [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

The debenzoylation of 2-[(amino)(benzoylamino)methylidene]cyclohexane-1,3-diones (addition products of cyclohexane-1,3-diones with benzoylcyanamide) affords the corresponding 2-diaminomethylidenecyclohexane-1,3-diones. The latter act as N,N-dinucleophiles in reactions with diethyl malonate in the presence of MeONa to form 6-hydroxy-2-(2,6-dioxocyclohexylidene)-1,2-dihydropyrimidin-4(3 H)-ones. This reaction performed at 200 °C in the absence of bases results in the subsequent self-condensation of the dihydropyrimidinones to give 4,5′-bipyrimidine derivatives. [ABSTRACT FROM AUTHOR]

4New hybrid systems based on a series of chalcones and containing pyrimidine, thiophene, and pyrrole fragments were synthesized, and their electrochemical properties were studied. [ABSTRACT FROM AUTHOR]