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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 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 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]

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]

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 condensation of 3-alkylamino-5-amino-1-phenyl[1,2,4]triazoles with β-keto esters or diethyl ethoxymethylenemalonate in the presence of acetic acid proceeds selectively to give 3-alkylamino-1-phenyl[1,2,4]triazolo[4,3- a]pyrimidin-5(1 H)-ones. The observed reaction pathway is explained using quantum-chemical calculations of the energies of possible isomeric heterocyclization products. [ABSTRACT FROM AUTHOR]

A method for the preparation of 4-amino-substituted tetrahydropyrimido[4,5- d]azocines containing an aromatic pyrimidine fragment has been developed. It was established that tetrahydropyrido[4,3- d]pyri-midines are cleaved by the action of activated alkynes with the formation of 6-vinylpyrimidines. [ABSTRACT FROM AUTHOR]

Synthetic approaches to the construction of bicyclic systems containing the imidazole nucleus have been considered. Methods for obtaining derivatives of imidazo[1,2- a]pyrazine and imidazo[1,2- a]pyrimidine have been studied, and methods have been developed for catalytic hydrogenation of these compounds. Partial reduction of the imidazole ring on imidazo[1,2- a]pyrimidine hydrogenation has been discovered for the first time. [ABSTRACT FROM AUTHOR]

Published information on heterocyclizations involving acetamidines and acetamidoximes substituted at the α-position with an electron-withdrawing group is reviewed, where these starting materials have been used in the synthesis of 2-aminoazaheterocycles (2-aminopyridines, 2-aminopyrroles, and 2-aminoazirines). In such reactions the α-carbon atom of the amidine or amidoxime is included in the ring of the obtained heterocycle. [ABSTRACT FROM AUTHOR]

Pyrazolo[3,4- d]thiazolo[3,2- a]pyrimidines were formed on halogenation of 5-allyl-6-thioxopyrazolo[3,4- d]-pyrimidin-4-one, whereas 5-ethylsulfanyl-2-halomethyl[1,3]oxazolo[3,2- c]pyrazolo[4,3- e]pyrimidinium tri-halogenides were formed from 5-allyl-6-ethylsulfanyl-1,5-dihydro-4H-pyrazolo[3,4- d]pyrimidin-4-one. [ABSTRACT FROM AUTHOR]

A method has been developed for the synthesis of new 8-amino-substituted 5-propyl(isobutyl)-1,2,3,4-tetra-hydropyrimido[4',5':4,5]furo[2,3- c]isoquinolines from 3-oxo derivatives of 5,6,7,8-tetra-hydroisoquinolines. Isomeric triazoles, condensed at the edge [ c] of the pyrimidine ring, have been obtained from the 8-hydrazino derivatives. A Dimroth rearrangement was carried out in acidic medium. [ABSTRACT FROM AUTHOR]

Methods are proposed for the preparation of fluorophosphorus-containing pyrimidines through three- component reactions of dialkyl (3,3,3-trifluoro-2-oxopropyl)phosphonates. Cyclocondensation of these phosphonates with urea and aryl aldehydes gave 6-aryl-4-hydroxy-2-oxo-4-trifluoromethylhexa-hydropyrimidin-5-ylphosphonates and reaction with urea and trialkyl orthoformates led to 4-alkoxy-2-oxo-4-trifluoromethyl-1,2,3,4-tetrahydropyrimidin-5-ylphosphonates. [ABSTRACT FROM AUTHOR]

The purpose-directed synthesis of a new heterocyclic system, 7,8-dihydroimidazo[1,2- c][1,3]thia- zolo[4,5- e]pyrimidine has been carried out based on the successive interaction of available 2-(aroyl- aminocyanomethylene)imidazolidines with hydrogen sulfide and triethyl orthoformate with subsequent intramolecular cyclocondensation of the obtained 8-aroylamino-7-thioxo-1,2,3,7-tetrahydroimidazo- [1,2-c]pyrimidines under the action of phosphorus pentasulfide or polyphosphoric acid. [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]

Condensation of ethyl ethoxymethyleneacetoacetate and ethyl ethoxymethylenecyanoacetate in ethanol with 3-substituted 3-aminopyrazoles and 5-amino-1,2,4-triazole gave the 2-substituted 6-ethoxy- carbonyl-7-methyl- and 7-amino-6-ethoxycarbonylpyrazolo[1,5-a]pyrimidines as well as 7-amino-6-ethoxycarbonyl-1,2,4-triazolo[1,5-a]pyrimidine. In the presence of alkali these rearranged to 2-substituted 6-acetyl-7-hydroxy- and 6-carbamoyl-7-hydroxypyrazolo[1,5-a]pyrimidines respectively and also to 6-carbamoyl-7-hydroxy-1,2,4-triazolo[1,5-a]pyrimidine. According to H (including NOESY) NMR spectroscopic data there were formed, along with the cyclization products, noncyclic condensation adducts (as cyano derivatives) from ethyl ethoxymethylenecyanoacetate with 5-aminopyrazoles. In the presence of alcoholic alkaline solution these were also transformed in high yield to 6-carbamoyl-7-hydroxypyrazolopyrimidines. When refluxed for a longer time in 12% aqueous alcoholic alkaline solution the 6-ethoxycarbonyl-2,7-dimethylpyrazolo[1,5-a]pyrimidine and 6-acetyl-7-hydroxy-2-methylpyrazolo[1,5-a]pyrimidine recyclize to give 6-carboxy-2,7-dimethyl- and 2,7-di- methylpyrazolo[1,5-a]pyrimidines. [ABSTRACT FROM AUTHOR]

The article offers information on the types of isomerizational recyclization in various pyridine, pyrimidine and pyrazine systems. It states that a recyclization scheme includes the attack of nucleophilic part, opening of the pyrimidine ring, subsequent cyclization that involves the exocyclic nitrogen atom of nitroso group. It discusses the rearrangement of 5,7-dihydroxy-2-methyl-3,6-dinitosopyrazolo[1,5-a]pyrimidine to 5-hydroxy-2-methyl-3-nitrosopyrazolo[1,5-b] [1,2,4] triazine.

A new series of pyrido[3',2':4,5]selenolo[3,2- d]pyrimidine derivatives is reported. The structures of the newly synthesized compounds were elucidated by elemental analyses and spectral data (IR, H and C NMR, MS). [ABSTRACT FROM AUTHOR]

The reactions of 2-aminonicotinamides with triethyl orthoformate, carboxylic acids chlorides, aldehydes, and 2-formylbenzoic acid were studied. As a result pyrido[2,3- d]pyrimidin-4(1H)-ones, 2,3-dihydropyrido[2,3- d]pyrimidin-4(1H)-ones, and 5,7,11b,12-tetrahydropyrido[2',3':4,5]pyrimido- [2,1- a]isoindole-5,7-diones were obtained. [ABSTRACT FROM AUTHOR]

2-(Acylaminocyanomethylene)imidazolidines are formed on interacting 2-acylamino-3,3-dichloro-acrylonitriles with ethylenediamine. The former are converted into new derivatives of oxazolo-[4,5-e]pyrimidine on treatment with trifluoroacetic acid, and then with triethyl orthoformate. [ABSTRACT FROM AUTHOR]

previously reported rearrangement of pyrimidine-5-carboxylic acids esters to 5-acylpyrimidones does not, in fact, occur in any of the examples studied by us. [ABSTRACT FROM AUTHOR]

Densely substituted methyl 5-amino-4-aryl-7-methyl-2-methylthio-7H-pyrrolo[2,3- d]pyrimidine-6-carboxy- lates were synthesized by the palladium-catalyzed cross-coupling reaction of methyl 5-amino-4-chloro-7-methyl-2-methylthio-7H-pyrrolo[2,3- d]pyrimidine-6-carboxylate with arylboronic acids using Pd(OAc)/dicyclohexyl(2-biphenyl)phosphine/KPO as a catalyst system. Reaction of methyl 5-amino-4-chloro-7-methyl-2-methylthio-7H-pyrrolo[2,3-d]pyrimidine-6-carboxylate with 2-formylphenyl- boronic acid led to a novel heterocyclic system - 1,3,4,6-tetraazadibenzo[ cd,f]azulene. [ABSTRACT FROM AUTHOR]

Some 6-(1H-1,2,3-triazol-1-yl)pyrimidine-2,4(1H,3H)-dione derivatives were synthesized via the reaction of 6-azido-1,3-dimethyluracil with ethyl acetoacetate in the presence of sodium ethoxide. The antiviral activities of these compounds against Hepatitis A virus (HAV, MBB-cell culture adapted strain) and Herpes simples virus type-1 (HSV-1) were tested. [ABSTRACT FROM AUTHOR]

Methods have been developed for the synthesis of novel derivatives of pyrano[3,4-c]pyridines, 2,7-naphthyridines, and condensed pyrido[2,3-d]pyrimidines by condensation of thiopyranthiones. [ABSTRACT FROM AUTHOR]

Acylation of pyrrolidin-2-ylidenemalononitrile with benzoyl chloride leads to the formation of 2-(1-benzoylpyrrolidin-2-ylidene)malononitrile. The obtained product was used as starting material in the synthesis of γ-aminopropylpyrazoles and pyrimidines. [ABSTRACT FROM AUTHOR]

The cyclocondensation reactions of 4-aminopyridothienopyrimidine with malonates and their acetylation were studied. All structures were determined by 1H NMR and mass spectra techniques. [ABSTRACT FROM AUTHOR]

Methyl esters of 5-aroyl-6-aryl-2-oxo-1,2,3,6-tetrahydropyrimidine-4-carboxylic acids were synthesized from three component mixtures of methyl esters of aroylpyruvic acids, urea, and substituted benzaldehydes. 8-Hydroxy-4,5-diphenyl-3,4-dihydropyrimido[4,5- d]pyridazin-2(1H)-one was synthesized by the reaction of 5-benzoyl-2-oxo-6-phenyl-1,2,3,6-tetrahydropyrimidin-4-carboxylate with hydrazine hydrate. [ABSTRACT FROM AUTHOR]

Thiazolo[3,2- a]pyrimidines were obtained in good yield by the reaction of 4-aryl-substituted 3,4-dihydropyrimidine(1H)-2-thiones and methyl chloroacetate in boiling toluene. Their structures were shown by 1H NMR spectroscopy and X-ray crystallography. [ABSTRACT FROM AUTHOR]

Reaction of 2-alkylthio-6-aminopyrimidin-4(3H)-ones with ethyl bromopyruvate to give ethyl 2-alkyl-thio-4-aminofuro[2,3- d]pyrimidine-5-carboxylates has been shown to proceed under neutral or acidic conditions. The obtained furo[2,3- d]pyrimidines underwent further cyclocondensation reaction with ethyl bromopyruvate to afford diethyl 5-alkylthiofuro[3,2- e]imidazo[1,2- c]pyrimidine-2,9-dicarboxy-lates. [ABSTRACT FROM AUTHOR]

Published data on the recyclization reactions of 1,3,5-triazines are reviewed. The classification is based on the fragments of the 1,3,5-triazine molecules used in the construction of new heterocycles. [ABSTRACT FROM AUTHOR]

It has been established that 5-vinyl-substituted (N-R,N-vinylaminomethyl)isoxazolo(thiazolo, thiadiazolo)pyrimidines are formed when tetrahydropyrido[3,4- d]pyrimidines, annelated with isoxazole, thiazole, and thiadiazole units are treated with terminal alkynes as a result of opening of the tetrahydropyridine ring. 7-Methoxymethyl-substituted [N-R,N-(dimethoxycarbonylvinyl)]aminoethyl-isoxazolo- and thiazolopyrimi-dines were obtained by reaction with dimethyl acetylenedicarboxylate (ADCE). Triazolo-pyrimidoazocine was obtained for the first time from tetrahydrotriazolopyrimidine and methyl propiolate. [ABSTRACT FROM AUTHOR]

The cyclocondensation products of N-aryl-3-oxobutanethioamides with 5-amino-3-R-4-R1-pyrazoles are 4-(arylamino)-2-methyl-7-R-8-R1-pyrazolo[1,5- a]pyrimidine and pyrazolo[1,5- a]pyrimidine-4-thione derivatives, the ratio of which depends on the nucleophilicity of the starting 5-amino-3-R-4-R1-pyrazoles and the presence of a proton donor solvent. [ABSTRACT FROM AUTHOR]

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. [ABSTRACT FROM AUTHOR]

A study was carried out on the amination of 2-chloro-and 2,4-dichloropyrimidines by linear polyamines and oxadiamines under catalytic and noncatalytic conditions. The reaction of excess polyamine with 2-chloropyrimidine gives the corresponding 2-aminopyrimidines, while the reaction of polyamines with excess of 2-chloropyrimidine gives di-, tri-, and tetraarylated derivatives. The reaction of 2,4-dichloropyrimidine with diamines was studied with different ratios of the starting reagents. The ratios of the products of substitution at pyrimidine C-2 and C-4 were found. [ABSTRACT FROM AUTHOR]

The ratio of dihydroindenopyridine regioisomers formed from ethyl β-amino-crotonate and 4-or 5-monosubstituted 2-arylideneindane-1,3-dione depends on the total electronic and steric effects of the indanedione substituents. [ABSTRACT FROM AUTHOR]

Treatment of methyl nitroacetate and 3-nitropropionate with formaldehyde and primary amines under Mannich reaction conditions gives 5-nitrohexahydropyrimidines. In the case of methyl nitroacetate both the 5-nitrohexahydropyrimidine and isomeric 3,5-di(methoxycarbonyl)-1-methyl-3,5-dinitropiperidines are formed. [ABSTRACT FROM AUTHOR]

The cyclocondensation of 3-amino-4-cyanopyrazole and 3-amino-4-ethoxycarbonylpyrazole with 1,3-diaryl-2,3-propen-1-ones gives the corresponding 3-substituted 5,7-diaryl-4,7(6,7)-dihydropyrazolo[1,5-a]pyrimidines. Their tautomeric composition in solution has been investigated by 1H NMR. [ABSTRACT FROM AUTHOR]

The interaction of the iodomethylates of pyrimidinyl-2-acetic acid derivatives with monosubstituted hydrazines, in addition to the products of a Kost-Sagitullin rearrangement, leads also to N-substituted triazoles. The structure of the triazoles was demonstrated by NOESY NMR experiments. The structure of the reaction products was determined on the basis of the response observed in the spectra between the methyl group protons of the triazole ring and the spatially close proton of the substituent in position 1 and a conclusion was drawn on the direction of the primary attack of nucleophile in the recyclization process of the pyrimidinium salts into a 1,2,4-triazole. [ABSTRACT FROM AUTHOR]

A method has been developed for the synthesis of 4-amino-substituted 7-benzyl-2-morpholin-4-yl-5,6,7,8-tetrahydropyrido[3,4-d]pyrimidines by condensation of ethyl 1-benzyl-3-oxopiperidine-4-carboxylate with morpholine-4-carboxamidine and subsequent reaction of the 7-benzyl-2-morpholin-4-yl-5,6,7,8-tetrahydro-3H-pyrido[3,4-d]pyrimidin-4-one with trifluoromethanesulfonic anhydride and secondary amines. [ABSTRACT FROM AUTHOR]

Condensation of ketene dithioacetal derivatives with some aminoazoles (5-aminotetrazole monohydrate, 2-aminobenzimidazole, 2-aminobenzothiazole, and 2-aminothiazole) in the presence or absence of triethylamine gave the corresponding tetrazolopyrimidines, benzimidazopyrimidines, benzothiazolopyrimidines, and thiazolopyrimidines. [ABSTRACT FROM AUTHOR]

The previously unknown three component condensation of hetarylguanidines, orthoesters, and active methylene carbonyl compounds has been studied. Depending on the nature of the latter products of both linear combination and subsequent cyclizationl leading to pyrimidine or tetrahydroquinazoline structures were obtained. [ABSTRACT FROM AUTHOR]

The recyclization of 2-R-7-hydroxy-3-(4-phenyl-1,2,4-triazol-3-yl)chromones using the binucleophiles hydroxylamine, hydrazine, or guanidine gave isoxazoles, 2-aminochromones, pyrazoles, or pyrimidines with a 4-phenyl-1,2,4-triazol-3-yl substituent. [ABSTRACT FROM AUTHOR]

The synthesis of 2-(2-furyl)imidazo[1,2-a]pyrimidine has been carried out. Azocoupling, nitrosation, and bromination by 1 mole of bromine occur at position 3 of the bicycle. Reaction with 2 mol of bromine gives the 3,5‰-disubstituted derivative. Bromination using 1 mol of bromine in 40% hydrobromic acid and sulfonation occur initially at the 5‰ position of the furyl group. [ABSTRACT FROM AUTHOR]

It has been shown from X-ray structural analytical data that the reaction of 2-ethoxycarbonylmethyl-1,4,6-trimethylpyrimidinium iodide with carboxylic acid hydrazides gives pyrazolo[1,5-a]pyrimidine derivatives and not the isomeric triazolo[4,3-a]pyridines previously reported. This novel and previously unreported rearrangement of 1,2-dialkylpyrimidinium salts occurs via recyclization of the pyrimidine ring with inclusion of a fragment of the nucleophilic reagent into the transformation product. [ABSTRACT FROM AUTHOR]

Data on the isomerization recyclizations of pyrimidines, particularly the Kost-Sagitullin and other transformations accompanied by substitution of an endocyclic atom in pyrimidine by an extracyclic nitrogen or carbon atom (N-N, N-C, or C-C recyclizations), are summarized and analyzed. Data from research on the Kost-Sagitullin and certain other isomerization transformations of pyrimidines at the Institute of Organic Chemistry, National Academy of Sciences of the Republic of Armenia, in recent years are presented. [ABSTRACT FROM AUTHOR]

A modification of the method for the synthesis of N(1)-substituted derivatives of uracil is proposed using the Gilbert-Johnson reaction, which consists of the alkylation of 5-substituted 2,4-bis(trimethylsiloxy)pyrimidines with 1-bromo-2-(phenoxy)ethanes of low reactivity at 180-185° without solvent. The corresponding 1-[2-(phenoxy)ethyl]uracils, which were obtained in 55-74% yield, contained no impurities of the N(1), N(3)-disubstituted compounds. [ABSTRACT FROM AUTHOR]

Products of additive cyclization with ring closure at the nitrogen atom of the thiohetaryl unit were synthesized by the interaction of 4,6-dimethylpyrimidine-2-, 3-cyano-4,6-dimethylpyridine-2-, quinoline-8-, and 1,3-benzothiazole-2-sulfenyl chlorides with 3,3-dimethyl-1-butene. [ABSTRACT FROM AUTHOR]

The synthesis of novel 1-{[2-(phenoxy)ethoxy]methyl}uracil derivatives with different substituents in positions and 6 of the pyrimidine ring has been carried out. It has been shown that the alkylation of trimethylsilyl derivatives of uracil with 2-(4-chlorophenoxy)- and 2-(4-methylphenoxy)ethoxymethyl chloride under Hilbert-Johnson reaction conditions gives N(1)-substitution products. It was found that the 1-{ [2-(phenoxy)ethoxy]methyl}uracil derivatives show viral inhibition properties relative to human immunodeficiency type 1 virus in vitro. The most active compounds are 5-bromo-6-methyluracil derivatives which suppress viral reproduction by 50% at 7.2 and 7.8 micromolar concentrations. [ABSTRACT FROM AUTHOR]

Condensation in ethanol of ethyl ethoxymethyleneacetoacetate with systems containing an amidine fragment (substituted 3-aminopyrazoles and 3-amino-1,2,4-triazole) gave 6-carbethoxy-7-methylpyrazolo[1,5-a]pyrimidines. Addition of base to solutions of the obtained bicyclic carbethoxy derivatives in the course of several minutes caused rearrangement to 6-acetyl-7-hydroxypyrazolo[1,5-a]pyrimidine and 6-acetyl-7-hydroxy-1,2,4-triazolo[1,5-a]pyrimidine respectively. A more prolonged refluxing in 15% aqueous alcohol solution of base caused 6-carbethoxy-7-methyl-2-phenylpyrazolo[1,5-a]pyrimidine and 6-acetyl-7-hydroxy-2-phenylpyrazolo[1,5-a]pyrimidine to recyclize to 7-methylpyrazolo[1,5-a]pyrimidine. [ABSTRACT FROM AUTHOR]