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A novel access to pyrrolo[3,4-d]pyrimidine scaffold via tandem Staudinger/intramolecular aza-Wittig reaction of 5-acyl-4-(1-azidoalkyl)-3,4-dihydropyrimidin-2(1H)-ones promoted by PPh3 was developed. Synthesis of the starting pyrimidinones involved the reaction of readily available N-[(2-azido-1-tosyl)alkyl]ureas with Na enolates of benzoylacetone or acetylacetone followed by acid-catalyzed dehydration of the resulting products without their isolation. [ABSTRACT FROM AUTHOR]

Routes were proposed for the synthesis of new pyrimidine-derived polycyclic nitrogen heterocycles – 4-(1H-pyrazol-1-yl)-2-(pyridin- 2-yl)pyrimidines with various donor substituents, isomeric 2-(1H-pyrazol-1-yl)-4-(pyridin-2-yl)pyrimidines, 2-(pyrazin-2-yl)-4-(1Hpyrazol- 1-yl)pyrimidines, and 4-(1H-pyrazol-1-yl)-2-(pyrimidin-2-yl)pyrimidines – which are of interest as N,N,N-tridentate ligands for the synthesis of transition metal coordination compounds. Experimental and theoretical studies of the electronic structure of the resulting compounds were carried out. [ABSTRACT FROM AUTHOR]

A series of homoisoflavonoids bearing 3-(het)arylcoumarin moiety were synthesized by cascade reaction of enaminones with 8-dimethyl- aminomethyl-7-hydroxy-3-(het)arylcoumarins. The further reaction of synthesized coumarin-isoflavone hybrids with bidentate nucleophiles led to the formation of substituted 7-hydroxy-8-(1H-pyrazol-4-ylmethyl)coumarins, 7-hydroxy-8-(isoxazol-4-ylmethyl)- coumarins, and 7-hydroxy-8-(pyrimidin-5-ylmethyl)coumarins. [ABSTRACT FROM AUTHOR]

One-pot efficient copper-catalyzed approach for the synthesis of tetracyclic chromeno[4',3':4,5]pyrimido[1,2-b]indazolone and chromeno[4,3-d]-[1,2,4]triazolo[4,3-a]pyrimidine derivatives as a class of pharmacologically interesting compounds through the intramolecular domino condensation–aza-Diels–Alder reaction of aminoazoles and o-propargylated salicylaldehydes under reflux conditions has been described. [ABSTRACT FROM AUTHOR]

This brief review presents recent advances at the Ivan Franko National University of Lviv in the application of Meerwein arylation for the synthesis of complex compounds including following heterocycles – 2-aminothiazoles, 2-aminoselenazoles, 3,4-dihydroisocoumarines, 3-hydroxythiophenes, dihydropyrimidin-2(1H)-ones, 3-arylpyran-2-ones, and heterocyclic systems such as pyrazolo[4,3-e]thiazolo[3,2-a]pyrimidine, 4,5-dihydro[1,2,3]triazolo-[1,5-a]pyrazin-6(7H)-ones, thienopyridinediones, 4H-thieno[2,3-c]-chromen-4-one, hexahydro-4H-furo[2,3-f]isoindoles. [ABSTRACT FROM AUTHOR]

A one-step method for the synthesis of new 5-aminoazolo[1,5-a]pyrimidines was developed. The use of a synthetic equivalent of carbonyl dielectrophile based on Meldrum's acid made it possible to introduce a substituted amino group into position 5 of azolo[1,5-a]-pyrimidines without the use of severe conditions and palladium catalysts. The tolerance of the reaction to various substituents was also investigated. Based on the isolated intermediates, a reaction mechanism of the process was proposed. Moreover, the possibility of synthesizing analogs of biologically active molecules based on the obtained compounds was demonstrated. [ABSTRACT FROM AUTHOR]

The review summarizes literature data on the methods of synthesis of o-aminopyrimidine aldehydes and o-aminopyrimidine ketones and their application for the construction of fused pyrimidines, in particular pyrido[2,3-d]pyrimidines, pyrimido[4,5-d]pyrimidines, pyrazolo-[3,4-d]pyrimidines, quinazolines, pyrimido[4,5,6-de]quinazolines, thieno[2,3-d]pyrimidines, pyrrolo[2,3-d]pyrimidines, cyclopenta[d]-pyrimidines, pyrimido[4,5-b]azepines, and pyrimido[4,5-b]quinolines. [ABSTRACT FROM AUTHOR]

The reaction of β-carbonyl-substituted 1H-benzo[f]chromenes with 3-amino-1,2,4-triazoles provides a new avenue for the preparation of [1,2,4]triazolo[1,5-a]pyrimidines containing a (2-hydroxynaphthalen-1-yl)methyl group at position 6. The reaction of 2-trifluoroacetyl-1Н-benzo[f]chromene with 3-amino-5-(methylsulfanyl)-1H-1,2,4-triazole yielded a derivative of a new 4,5,5a,13a-tetrahydro-6H-benzo-[5,6]chromeno[3,2-e][1,2,4]triazolo[1,5-a]pyrimidine heterocyclic system. The proposed cascade reaction mechanism includes an aza-Michael reaction, cyclodehydration, and a retro-oxa-Michael reaction. [ABSTRACT FROM AUTHOR]

Ribociclib and palbociclib, two typical selective CDK4/6 inhibitors, which have been employed in clinic for the treatment of estrogen receptor positive (ER+) breast cancer, possess an active fragment of pyrrolo[2,3-d]pyrimidine and pyrido[2,3-d]pyrimidine, respectively. Herein, 25 novel pyrrolo(pyrido)[2,3-d]pyrimidine derivatives have been designed and synthesized based on molecular diversity. Their antiproliferative activity was evaluated against ER+ (T47D) and triple-negative (MDA-MB-436) breast cancer cell lines. The obtained results demonstrated that dihydroartemisinin-pyrrolo[2,3-d]pyrimidine and dihydroartemisinin-pyrido[2,3-d]pyrimidine derivatives are characterized by significant antiproliferative effects on both cell lines and have higher anticancer activity against triple-negative breast cancer cells compared to ribociclib. [ABSTRACT FROM AUTHOR]

A method for the introduction of the N,N-dimethylformamidine protective group in a series of six-membered 2-aminohetarene N-oxides was developed. It was shown that 2-amino derivatives of N-oxides of various six-membered heterocycles (pyridines, pyrimidines, pyrazines, tetrazines) successfully enter the reaction. The stability of the N,N-dimethylformamidine protecting group in 2-aminohetarene N-oxides was found to depend on the type of reaction medium. [ABSTRACT FROM AUTHOR]

The alkaloid 4-O-methylsinomenine was modified by introducing pyrimidine substituents at the C-1 position of the backbone. Two methods were used to synthesize these hybrid molecules. The first method involves the preparation of 1-ethynyl-4-O-methylsinomenine and a sequence of cross-coupling reactions with benzoic acid chlorides and cyclocondensation with amidines. The second method is based on palladium-catalyzed carbonylation–cross coupling of 1-iodo-4-O-methylsinomenine with phenylacetylene in the presence of Mo(CO)6 as a source of CO in MeCN and subsequent cyclocondensation of alkynyl ketone with amidines. The carbonylation–crosscoupling reaction proceeded selectively in the presence of the PdCl2/(1-Ad)2PBn catalytic system. [ABSTRACT FROM AUTHOR]

A new method for the synthesis of quinazolines based on the annulation of the benzene ring to 5-acetyl-6 methylpyrimidin-2-one(thione) derivatives has been proposed. Condensation of the latter at the methyl group with dimethylformamide dimethyl acetal in boiling PhH leads to the formation of 5-acetyl-6-[2-(dimethylamino)vinyl]pyrimidin-2-ones(thiones), which, when boiled with MeONa in MeOH, cyclize to 5-hydroxyquinazolin-2-ones(thiones). Similarly, 5-acetyl-6-methyl-4-(trifluoromethyl)pyrimidine was converted to 5-hydroxy-4-(trifluoromethyl)quinazoline. Quinazolines are not formed from 5-acetyl-6-methylpyrimidines condensed with dimethylformamide dimethyl acetal at the acetyl group, but 5-acetyl-6-methylpyrimidines can be used to obtain pyrido[2,3-d] pyrimidine derivatives. [ABSTRACT FROM AUTHOR]

New derivatives of imidazo[1,5-a]pyrimidine have been synthesized by cyclization of in situ generated 1H-imidazol-4(5)-amine with 1,3-diketones or malondialdehyde derivatives. Utilization of asymmetrical 1,3-diketones leads to the formation of a mixture of regioisomers. The discovered conversion of imidazo[1,5-a]pyrimidine core into 3H-imidazo[4,5-b]pyridine that takes place only under acidic conditions can be considered as a new version of Dimroth rearrangement involving cleavage of C–N bond and formation of C–C bond. [ABSTRACT FROM AUTHOR]

Nonannulated tetrazolylpyrimidines in the structure of which the heterocyclic fragments are separated by hydrazinocarbonylmethyl, methylpyrazolyl groups or a sulfur atom were synthesized. Some of these compounds showed moderate in vitro activity against H1N1 subtype of influenza A virus. The selectivity index of the anti-influenza action of {5-[(4,6-dimethylpyrimidin-2-yl)sulfanyl]-1H-tetrazol-1-yl}acetic acid, which has very low cytotoxicity, was twice as high as the selectivity index of the reference drug rimantadine. [ABSTRACT FROM AUTHOR]

The synthesis of new cyclopenta[4',5']pyrido[3',2':4,5]furo[3,2-d]pyrimidin-7-amines have been carried out to study their antimicrobial activity. The biological tests evidenced that some of the synthesized compounds exhibit pronounced antimicrobial properties. A study of the structure–activity relationship revealed that the 3,5-dimethyl-1H-pyrazol-1-yl moiety linked to the carbon C-9 of the pyrimidine plays a decisive role in the manifestation of activity. The influence of 3,5-dimethyl-1H-pyrazol-1-yl group on the Dimroth rearrangement and azide-tetrazole equilibrium has also been examined. [ABSTRACT FROM AUTHOR]

The mechanism of a multicomponent reaction between aminoazoles, 1-morpholino-2-nitroalkenes, and benzaldehyde was studied in acidic medium. Performing the reaction in acetic acid led to the formation of 6-nitro-5-phenyl-4,5,6,7-tetrahydropyrazolo[1,5-a]-pyrimidines, which subsequently underwent a rearrangement. Reaction conditions were proposed for a multicomponent synthesis with trioxane, and the alkylation reactions of 4,7-dihydroazolo[1,5-a]pyrimidine nitro derivatives were optimized. [ABSTRACT FROM AUTHOR]

This review considers methods for the synthesis of pyrimido[1,2-a]indoles and their ring-fused derivatives, covering publications from the last 10 years. Depending on the synthons used for assembling the target structure, three main approaches to the synthesis of pyrimido-[1,2-a]indoles can be distinguished: annulation of a pyrimidine ring to 2-aminoindoles, modification of other indole derivatives, and miscellaneous methods. [ABSTRACT FROM AUTHOR]

A new multicomponent reaction for regioselective synthesis of substituted 1,2,4-triazolo[1,5-a]pyrimidines using aminotriazoles, β-ketoglutaric acid dimethyl ester, and dimethylformamide dimethyl acetal was implemented. The selective reduction of 1,2,4-triazolo-[1,5-a]pyrimidines to dihydro derivatives and the use of triazolo pyrimidines as starting compounds in multicomponent synthesis of dihydropyrido[3,4-е][1,2,4]triazolo[1,5-a]pyrimidinecarboxylates was demonstrated. [ABSTRACT FROM AUTHOR]

Reactions of five- and six-membered cyclic β-alkoxyvinyl α-keto esters and NCC-binucleophiles are described. The following binucleophiles were studied: heteroaromatic amines (pyrazoles, isoxazole, uracils, and isoquinolinone) and 2-(benzimidazolyl)acetonitrile. It was found that condensation proceeded regioselectively in the case of five-membered cyclic enone. Fused α-pyridine carboxylates, likely formed in situ, underwent lactonization, which resulted in six-membered lactones in moderate to excellent yields (53–91%). Only in the case of 3-unsubstituted 5-aminopyrazole, formation of γ-pyridine carboxylate followed by cyclization to isomeric lactone was observed. On the contrary, six-membered cyclic enone was reactive only toward heterocyclic amines under optimized conditions and provided open-chain α-pyridine carboxylates in 40–80% yield. [ABSTRACT FROM AUTHOR]

1-Alkyl-N-Boc-5-formylpyrazol-4-amines react with malononitrile and cyanoacetamide to form 5-amino-1H-pyrazolo[4,3-b]pyridine nitriles and amides, respectively. Cyclocondensation of the obtained derivatives with chloroacetaldehyde, bromotrifluoroacetone, or ethyl bromopyruvate leads to the formation of imidazo[1,2-a]pyrazolo[3,4-e]pyridines or to pyrazolo[3′,4′,5,6]pyrido[2,3-d]pyrimidine derivatives in cyclocondensation with orthoesters, ethyl oxalyl chloride, or carbonyldiimidazole. [ABSTRACT FROM AUTHOR]

A reaction of 3-oxobutanoyl-containing podands with thiophene-2-carbaldehyde (or benzaldehyde) and 3-amino-1,2,4-triazole gave podands featuring a 4,7-dihydro[1,2,4]triazolo[1,5-а]pyrimidine motif. It was established that the process was accompanied by the formation of [4,3-а]-isomers, which occurred in a slight excess during the synthesis of a podand containing a phenyl group at position 7 and, on the other hand, were observed as the minor products during the synthesis of podands bearing a thiophen-2-yl substituent. Trace amounts of monosubstituted podands were also detected, containing a free hydroxy group along with the triazolodihydropyrimidine pharmacophore. [ABSTRACT FROM AUTHOR]

Triazolo[4,3-a]pyrimidines were prepared by the reduction of 5,6,7-trisubstituted 2-(arylhydrazinylidene)-5H-[1,3]thiazolo[3,2-a]- pyrimidin-3(2H)-ones with NaBH4 in the presence of V2O5 at room temperature. The structure of ethyl 3-(hydroxymethyl)- 5-(4-methoxyphenyl)-7-methyl-1-phenyl-1,5-dihydro[1,2,4]triazolo[4,3-a]pyrimidine-6-carboxylate was proven by the single crystal X-ray diffraction data. The mechanism of the reaction including transition cage structure is discussed. [ABSTRACT FROM AUTHOR]

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]

The cross coupling of 5'-ethynyllappaconitine with benzoic acid chlorides under the conditions of the Sonogashira reaction in benzene leads to the corresponding 5-alkynones. By condensation of the obtained 5'-alkynones with amidines, compounds with hybrid structure containing fragments of a diterpene alkaloid and pyrimidine were synthesized. The yields of the target compounds were 67-90%. The possibility of carrying out the cross coupling - condensation reaction as a one-pot synthesis is demonstrated. [ABSTRACT FROM AUTHOR]

In this work, we provide the first generalized and critical analysis of data on the chemistry of malononitrile dimer (2-aminopropene-1,1,3-tricarbonitrile) - a multifunctional reagent that is widely used for the preparation of diverse heterocyclic systems. The majority of references are from the last 20-25 years. [ABSTRACT FROM AUTHOR]

An efficient green synthesis of novel 3-(4-aminothieno[2,3-d]pyrimidin-5-yl)coumarins has been developed. One-pot reaction of 3-acetylcoumarin, malononitrile, and elemental sulfur, catalyzed by L-proline, resulted in the formation of thiophene derivatives, which were used as precursors for the synthesis of 3-(4-aminothieno[2,3-d]pyrimidin-5-yl)coumarins. Target compounds were prepared by a one-pot method or stepwise, and NH4OAc was exploited as a reagent and molten salt. Microwave irradiation method was successfully applied to afford the products in excellent yields. [ABSTRACT FROM AUTHOR]

An improved seven-step synthesis of 4-chloro-7H-pyrrolo[2,3-d]pyrimidine from dimethyl malonate with 31% overall yield is described. The procedure is operationally simple and practical for the synthesis of the 4-chloro-7H-pyrrolo[2,3-d]pyrimidine building block. [ABSTRACT FROM AUTHOR]

A sequence of microwave-assisted Suzuki cross-coupling reaction and bromination with N-bromosuccinimide was used for the synthesis of 3,3'-(5,5'-{5-[5-(9-ethyl-9H-carbazol-3-yl)-3-hexylthiophen-2-yl]pyrimidine-4,6-diyl}bis(thiophene-5,2-diyl))bis(9-ethyl-9H-carbazole). The obtained compound was characterized with regard to its optical properties, as well as possible applications in sensors for nitroaromatic compounds in acetonitrile solutions and in vapor phase. [ABSTRACT FROM AUTHOR]

The first annulated heterocyclic derivatives of tetrahydro-2-pyrimidin-2(1H)-one were synthesized in one preparative step on the basis of a solventless three-component reaction of tetrahydro-2-pyrimidin-2(1H)-one with 1-iodopropan-2-one, 2-iodo-1-phenylethan-1-one, 2-iodo-1-(thiophen-2-yl)ethan-1-one, or 1,3-diiodopropan-2-one and elemental iodine in the absence of a base. [ABSTRACT FROM AUTHOR]

A method was developed for the synthesis of 7-alkylamino-5-methyl-6-nitrotetrazolo[1,5-a]pyrimidines from the readily available 5-methyl-6-nitrotetrazolo[1,5-a]pyrimidin-7(4H)-one by using a sequence of chlorodeoxygenation and amination reactions. The chlorinated intermediate formed along this route was isolated and characterized as 7-chloro-5-methyl-6-nitrotetrazolo[1,5-a]pyrimidine. [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]

The possibility of intramolecular nucleophilic aromatic substitution of hydrogen in the series of 5-[2-(het)aryl-1-benzothiophen-3-yl]-pyrimidines was explored. A convenient method for the synthesis of [1]benzothieno-[3,2- f]thieno[2,3- h]quinazoline and [1]benzothieno-[3,2- f]thieno[3,2- h]quinazoline based on the developed S protocol was proposed. The energy parameters (width of the band gap, the energy of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbitals (LUMO)) of benzothieno[3,2- f]-thieno[2,3- h]quinazoline synthesized for the first time were determined based on the data of the absorption spectra and cyclic voltammetry. [ABSTRACT FROM AUTHOR]

β-Ketoacids reacted with 4-(trifluoromethyl)pyrimidin-2(1 Н)-ones according to the mechanism of Michael addition-decarboxylation, forming 4-(2-oxoalkyl)-6-(trifluoromethyl)-3,4-dihydropyrimidin-2-ones. [ABSTRACT FROM AUTHOR]

The reaction of 4,6-dichloropyrimidine-5-carbaldehyde with cyanomethyltriphenylphosphonium chloride gave (2 Е)-3-(4,6-dichloropyrimidin-5-yl)acrylonitrile, which was further used for the preparation of 4,6-diamino-substituted pyrimidinylacrylonitrile derivatives, capable of intramolecular cyclization with the formation of new 4-amino-substituted 7-iminopyrido[2,3- d]pyrimidines. Performing the reaction with 4-amino-6-chloropyrimidine-5-carbaldehyde led to 7-amino-4-chloropyrido[2,3- d]pyrimidine, a promising intermediate for the synthesis of pyrido[2,3- d]pyrimidine-4,7-diamines. [ABSTRACT FROM AUTHOR]

A series of 2-[(pyrimidin-5-yl)methyl]phenols and 1-[(pyrimidin-5-yl)methyl]-2-naphthols have been accessed via the interaction of carbonyl-substituted 4 H-chromenes and 1 H-benzo[ f]chromenes with amidines and guanidine in a reaction cascade initiated by the Michael reaction. It was established that in this transformation chromenes act as the synthetic equivalents of hydroxybenzylated α-formyl ketones or α-formylaldehydes. [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]

Simple aromatic substituents in the substrate molecule, including pyrimidine, pyridine, and benzene rings, directly facilitated the intramolecular cycloaddition of azomethine ylide to alkene. All of these aromatic substituents aided the formation of azomethine ylides, which then underwent highly diastereospecific sequential cycloaddition. It was shown that both the presence of an electron-deficient aromatic ring and a substituent at ortho position of the aromatic ring relative to the aminomethyl group enhanced the reactivity of azomethine ylides towards cycloaddition. [ABSTRACT FROM AUTHOR]

[MediaObject not available: see fulltext.]The effect of pyrimidine ring saturation in 2-amino[1,2,4]triazolo[1,5- а]pyrimidines on their reactivity as polyfunctional N-nucleophiles was studied by computational methods (reactivity indices and transition state energy values for the model reaction of S2 alkylation with chloromethane, DFT B3LYP/6-311++G(2d,2p)), as well as experimentally (alkylation with benzyl bromide). The global nucleophilicity of partially hydrogenated aminotriazolopyrimidines was shown to be substantially higher than for aromatic analogs. The most likely sites for electrophilic attack in partially hydrogenated aminotriazolopyrimidines were the N-1 and N-3 atoms, as well as the amino group, and the probability of attack at the N-3 atom increased with harder electrophiles. The nucleophilicity of amino group and the N-1 atom was substantially decreased in aromatic aminotriazolopyrimidines, where the most likely sites of attack by hard electrophiles were the N-3 and N-4 atoms. [ABSTRACT FROM AUTHOR]

[Figure not available: see fulltext.] Alkylation of 6-C(O)R-7-aryl-5-methyl-4,7-dihydro[1,2,4]triazolo[1,5- a]pyrimidines with methyl iodide or ethyl bromide in either saturated aqueous KОН-MeCN or NaH-DMF led to the formation of N-alkyl derivatives in good yields (60-98%). Reactivity of the acetyl group of N-alkyl derivatives towards aromatic aldehydes under the conditions of the Claisen-Schmidt reaction was significantly higher than in 4-unsubstituted compounds. The starting 6-C(O)R-7-aryl-5-methyl-4,7-dihydro[1,2,4]triazolo[1,5- a]pyrimidines were synthesized via a three-component condensation of an aromatic aldehyde, 3-amino-1,2,4-triazole, and a dicarbonyl compound (2,4-pentanedione or ethyl acetoacetate) in DMF. [ABSTRACT FROM AUTHOR]

[Figure not available: see fulltext.] 3-Diazopyrrolidones, prepared by nitrosation of 3-aminopyrrolidones with isoamyl nitrite in the presence of glacial acetic acid, enter in a 1,3-dipolar cycloaddition reaction with dimethyl ester of acetylenedicarboxylic acid to form tetrahydropyrazolo[1,5- c]pyrimidines in good yields. [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]

[Figure not available: see fulltext.] We studied the reaction of 2-(ethoxycarbonyl)methyl-1,4,6-trimethylpyrimidinium iodide with hydrazides of N-azolyl- and С-pyrazolylsubstituted carboxylic acids, which were synthesized by reacting the respective esters with hydrazine hydrate. This reaction was shown to result in recyclization and formation of ethyl 2-(pyrazolylalkyl)- and 2-(azolylalkyl)-5,7-dimethylpyrazolo[1,5- a]pyrimidine-3-carboxylates. Besides pyrazolopyrimidines, the separation of reaction mixture provided in some cases also another recyclization product, 2-hydroxy-5,7-dimethylpyrazolo[1,5- a]pyrimidine. [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]

[Figure not available: see fulltext.] 2-(Chloromethyl)-5,6,7,8-tetrahydropyrido[4',3':4,5]thieno[2,3- d]pyrimidin-4(3 Н)-ones reacted with acetylenedicarboxylate ester, methyl propiolate or acetylacetylene, forming mixtures of 2-(chloromethyl)-5,6,7,10-tetrahydropyrimido[5',4':4,5]thieno[3,2- d]azocin-4(3 Н)-ones and 2'-chloromethyl-6'-methylidene-2,3-dihydro-1 Н-spiro[pyrido[4,5']thieno[2,3- d]pyrimidin]-4'(3' H)-ones in various ratios. Analogous products were also obtained in the reaction of 2-(methoxymethyl) derivative with methyl propiolate, while using 2-[(morpholin-4-yl)-methyl] derivative in a similar reaction led to the formation of a more complex product mixture. [ABSTRACT FROM AUTHOR]

The interaction of ortho-aminoaryl polyethers, derivatives of mono-, di-, and triethylene glycol, with acetyl ketene, generated from 2,2,6-trimethyl-4H-1,3-dioxin-4-one produced acetoacetanilide- containing podands. 2,2,6-Trimethyl-4H-1,3-dioxin-4-one reacted with aminoaryl-substituted podands containing a short polyether chain (1-2 atoms) in toluene medium without catalyst. Acetoacetanilide- containing podands with longer polyether chains could be obtained by using triethylamine or acetic acid as catalyst. Acetoacetanilide-containing podands were used in the Biginelli reaction as СН-active components. [ABSTRACT FROM AUTHOR]

Novel organic dyes containing pyridine ring as the anchoring group with carbazole or triphenylamine substituents were synthesized from available 4-(2-thienyl)pyrimidine using the Kost-Sagitullin rearrangement and Suzuki cross coupling assisted by microwave irradiation. The photophysical (absorption and photoluminescence spectra) and electrochemical properties of these compounds were investigated. The data from quantum calculations show that all of the dyes are potentially good photosensitizers for dye-sensitized solar cells. [ABSTRACT FROM AUTHOR]

A novel method has been developed for the synthesis of 8-alkyl[1, 2, 4]triazolo[5,1-b]purines from 6-nitro[1,2,4]triazolo[1,5-a]pyrimidin-7-ones via successive phosphoryl chloride-mediated chloro-desoxygenation, aminodehalogenation, and reduction to give 7-alkylamino-6-amino[1,2,4]triazolo-[1,5-a]pyrimidines. The latter can be cyclized in the presence of formic acid. [ABSTRACT FROM AUTHOR]

We have optimized the reaction conditions for the synthesis of 2-methylsulfanyl-6-polyfluoro-alkylpyrimidin-4-ones. In particular the yield of trifluoromethyl-substituted heterocycle was increased to 96%, and new polyfluoroalkyl-substituted analogs were prepared. The interaction of these heterocycles with morpholine or hydrazine was shown to result in nucleophilic substitution of the methylsulfanyl group, leading to 2-morpholino- and 2-hydrazino-6-polyfluoroalkylpyrimidin-4-ones. The reaction of 2-(2-phenylhydrazino)-6-trifluoromethylpyrimidin-4-one with paraform produced 5-oxo-2-phenyl-7-tri-fluoromethyl-5H-1,2,4-triazolo[4,3-а]pyrimidin-1-id-2-ium. The lactam structure of the synthesized heterocycles was established by X-ray structural analysis, as well as by IR and NMR spectroscopy. [ABSTRACT FROM AUTHOR]

The reaction of 2-aryl-4-cyano-1,3-oxazole-5-sulfonyl chlorides with 5-amino-3-R-1 H-pyrazoles and 5-amino-1 H-1,2,4-triazole gave 5-[(3-R-5-amino-1 H-pyrazol-1-yl)sulfonyl]-2-aryl-1,3-oxazole-4-carbo- nitriles and 5-[(5-amino-1 H-1,2,4-triazol-1-yl)sulfonyl]-2-aryl-1,3-oxazole-4-carbonitriles. The action of sodium hydride on these carbonitriles leads to the elimination of sulfur dioxide and cyclocondensation to give new heterocyclic systems, namely, [1,3]oxazolo[5,4- d]pyrazolo[1,5- a]-pyrimidine and [1,3]oxazolo[5,4- d][1,2,4]triazolo[1,5- a]pyrimidine. [ABSTRACT FROM AUTHOR]

The Biginelli reaction of methyl propiolate and of methyl 3-diethylaminoacrylate has yielded a novel series of 6-unsubstituted 3,4-dihydropyrimidin-2(1 H)-ones. The successie oxidation of the pyrimidine ring, chlorination of the 2-oxo group, and substitution of the chlorine atom by an aromatic amine give previously unknown 2-(arylamino)pyrimidines. 2-Oxo- and 2-(arylamino)pyrimidine-5-carboxylic acids have been obtained. [ABSTRACT FROM AUTHOR]