Synthesis of selected 3-substituted-pyrimido[5,4-e]1,2,4-triazine-5,7-diamines as potential folate antagonists

3-(Anilinomethy1) 3-[(arylthio)methy1]pyrimido[5,4-e]-1,2,4-triazine-5,7-diamines were prepared by ring closure of 6-hydrazino-4-[(phenylmethy1)thio]-2.5-pyrimidinediamine. these nonclassical analogs of known potent dihydrofolate reductase inhibitors were inactive against malarial infections in mice and L1210 leukemia in vitro.     

Synthesis of pyrido[2,3-d]pyrimidine-2,4-diones from pyrimido-[4,5-e]-1,2,4-triazine-6,8-diones by reversed azadiene synthesis

It was shown that pyrimido[4,5-e]-1,2,4-triazine-6,8-diones enter the reversed azadiene synthesis reaction with ketones and vinyl ethyl ether in the presence of diethylamine or boron trifluoride etherate, and also with enamines. As a result of the reaction, pyrido[2,3-d]pyrimidine-2,4-diones are formed in good yield. Pyrimido[5,4-e]-1,2,4-triazine-5,7-diones do not undergo such reactions with acetone. The reasons for the unique behavior of the isomeric pyrimidotriazinediones in the reaction with acetone are discussed.For a preliminary communication, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 224–233, February, 1990.     

A novel synthesis of N(1)-(substituted)-pyrimido[5,4-e]-1,2,4-triazine-5,7(1H,6H)-diones

A new synthesis of N₁-(substituted)-pyrimido[5,4-e]-1,2,4-triazine-5,7(1H,6H)-diones, which are analogues of the natural product toxoflavin, is reported. Condensation of preformed alkyl or aryl hydrazones with 6-chloro-3-methyl-5-nitrouracil efficiently provides pyrimidotriazinediones in a three-step process that broadens the scope of R₁ substituents.     

Diethylamine and triethylamine as sources of the dienophile component in the reverse azadiene synthesis with dimethylpyrimido[4,5-e]- and-[5,4-e]-1,2,4-triazinediones and 1,2,4,5-tetrazines

Diethylamine (DEA) and triethylamine (TEA) can function as sources for the two-carbon component in the reverse azadiene synthesis. Reaction of 5,7-dimethylpyrimido[4,5-e]-1,2,4-triazine-6,8-dione, 6,8-dimethylpyrimido-[5,4-e]-1,2,4-triazine-5,7-dione, or 1,2,4,5-tetrazine with an excess of DEA or TEA gives, respectively, the pyrido[2,3-d]pyrimidine-2,4-dione,pyrido[3,2-d]pyrimidine-2,4-dione, or pyridazine. The presence of an oxidant (atmospheric oxygen, MnO₂, or an electron-acceptor solvent) is required for the reaction to occur. Reaction of 5,7-dimethylpyrimido[4,5-e]-1,2,4-triazinedione with piperidine, morpholine, or under certain conditions DEA, results in opening of the triazine ring to give uracils with an amidine group in the 6-position.For preliminary communication, see [1, 2].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1545–1558, November, 1990.     

Syntheses and properties of 4,6-dimelhyl[1,2,5]oxadiazolo[3,4-d]pyrimidine-5,7(4H,6H)dione 1-oxide

New convenient syntheses of 4,6-dimethyl[1,2,5]oxadiazolo[3,4-d]pyrimidine-5,7(4H,6H)-dione 1-oxide (I) from 1,3-dimethyl-6-hydroxylaminouracil by means of nitrosative and nitrative cyclizations are described. Compound I was converted into 4,6-dimethyl[1,2,5]oxadiazolo[3,4-d]pyrimidine-5,7(4H,6H)dione [4,6-dimethyl-5,7(4H,6H)furazano[3,4-d]pyrimidinedione] by refluxing in dimethylformamide. Transformation of I to 1,3,7,9-tetramethyl-2,4,6,8(1H,3H,7H,9H)pyrimido[5,4-g]pteridinetetrone and/or 1,3,6,8-tetramethyl-2,4,7,9(1H,3H,6H,8H)pyrimido[4,5-g]pteridinetetrone is described.     

Synthesis of condensed heterocycles containing a pyrimido[5,4-e][1,3]-thiazine fragment

The cyclocondensation of 4,6-dichloro-2-methylthiopyridine-5-carbaldehyde and heterocyclic thiones such as 1,2,4-triazole-5-thione, imidazolidine-2-thione, imidazole-2-thione, and 4,5-diphenylimidazole-2-thione in dimethylformamide gave tricyclic heterocycles containing a pyrimido[5,4-e][1,3]thiazine fragment. The reaction of 6-chloro-8-methylthio-5H-pyrimido[5,4-e][1,2,4]triazolo[5,1-b][1,3]thiazin-5-ol with diethylamine, pyrrolidine, and morpholine gave the corresponding 6-dialkylaminopyrimidotriazolothiazines.Vilnius University, 2006 Vilnius, Lithuania; e-mail: sigitas.tumkevicius@chf.vu.lt. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 854–856, June, 2000.     

Sequence of the conversion of pyrimido [5,4-e]-1,2,4-triazinediones to imidazo[4,5-e]-1,2,4-triazinones

The conversion of pyrimido[5,4-e]-1,2,4-triazinediones to imidazo[4,5-e]-1,2,4-triazinones is a multistage process including the hydrolysis of the C₍₅₎-N₍₆₎ amide bond, the closure of the ureido group to the imidazolidinone ring, decarboxylation, acid oxidation.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1252–1259, September, 1987.     

Purines, pyrimidines, and related fused systems. 21. Oxidative amination of 3-chloro-6,8-dimethylpyrimido[4,5-c]pyridazine-5,7(6H,8H)-dione

Oxidative amination of 3-chloro-6,8-dimethylpyrimido[4,5-c]pyridazine-5,7(6H,8H)-dione with primary alkylamines and potassium amide in liquid ammonia gives rise to the corresponding 4-amino derivatives as the major products. The reactions with acyclic secondary amines are accompanied by annelation of the pyrrole moiety to the starting heterosystem to form 1-R-3-R"-6,8-dimethylpyrrolo[2",3";3,4]pyrimido[4,5-c]pyridazine-7,9(6H,8H)-diones. The reaction with piperidine as the aminating agent occurs exclusively as aminodehalogenation. The Sonogashira cross-coupling of 4-amino-3-chloro-6,8-dimethylpyrimido[4,5-c]pyridazine-5,7(6H,8H)-diones with terminal alkynes affords 1-R-2-R"-6,8-dimethylpyrrolo[3",2";3,4]pyrimido[4,5-c]pyridazine-7,9(6H,8H)-diones.     

Study of Nitrogen- and Sulfur-Containing Heterocycles. 57. Synthesis and Conversion of 4′-Substituted 5-(5-Amino-6-Pyrimidylthio)-2,2-Dimethyl-4,6-Dioxo-1,3-Dioxanes

By reaction of 4-substituted 5-amino-6-mercaptopyrimidines with 5-bromo-2,2-dimethyl-4,6-dioxo-1,3-dioxane, we have obtained 4′-substituted 5-(5-amino-6-pyrimidylthio)-2,2-dimethyl-4,6-dioxo-1,3-dioxanes. We have studied diazotization of these compounds by isoamyl nitrite. In the case of 4′-methoxy- and 4′-dimethylamino-substituted derivatives, we have obtained derivatives of novel heterocyclic systems: pyrimido[5,4-e][1,3,4]thiadiazine and pyrimido[5,4-e][1,3,4]thiadiazine-7-spiro-5′-1,3-dioxane, and in the case of the 4′-isopropylamino-substituted derivative we obtained 4-isopropyl-7-(2,2-dimethyl-4,6-dioxo-1,3-dioxan-5-ylidene)-1,2,3-triazolo[5,4-d]pyrimidin-7-ylidene.__________Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 613–623, April, 2005.     

The synthesis of pyrimido[4,5-c]pyridazines and pyrimido[5,4-c]pyridazines

The Hofmann reaction on 6-methylpyridazine-3,4-dicarboxamide (1) gave a mixture of 3-methylpyrimido[4,5-c]pyridazine-5,7-dione (2), 3-methylpyrimido[5,4-c]pyridazine-6,8-dione (3) and an acid (4) of unknown structure. The Hofmann reaction on pyridazine-3,4-dicarboxamide (9) gave a mixture of pyrimido[4,5-c]pyridazine-5,7-dione ( 10 ) and an acid ( 11 ) of unknown structure. The reaction of 3-amino-6-methylpyridazine-4-carboxamide ( 18 ) with ethyl orthoformate gave 3-methylpyrimido[4,5-c]pyridazin-5-one ( 21 ). 4-Aminopyridazine-3-carboxamide ( 36 ) upon fusion with urea gave pyrimido[5,4-c]pyridazine-6,8-dione ( 37 ) while with ethyl orthoformate 36 gave pyrimido[5,4-c]pyridazin-8-one ( 38 ). Pyrimido[5,4-c]-pyridazine-8-thione ( 39 ) was obtained by the action of phosphorus pentasulfide on 38. 4-Amino-3-cyanopyridazine ( 16 ) when treated with formamide produced 8-aminopyrimido[5,4-c]-pyridazine ( 41 ). The synthesis of 4-aminopyridazine-3-carboxamide ( 36 ) and 4-amino-3-cyanopyridazine ( 16 ), both key intermediates in the synthesis of the novel pyrimido[5,4-c]pyridazine ring system was accomplished by the Reissert reaction of 4-aminopyridazine-2-oxides and subsequent conversion of the nitrile to the amide.     

Purines, Pyrimidines, and Condensed Systems Based on them. 18. Reaction of 6,8-Dimethylpyrimido[4,5-c]pyridazine-5,7(6H,8H)dione N(2)-oxide with Alkylamines

Heating 6,8-dimethylpyrimido[4,5-c]pyridazine-5,7(6H,8H)-dione N₍₂₎-oxide (2) with piperidine or morpholine gave a moderate yield of 3-piperidino- and 3-morpholino-6,8-dimethylpyrimido[4,5-c]pyridazine-5,7(6H,8H)-diones (3a,b). Reaction of N-oxide (2) with ammonia and alkylamines in the presence of an oxidant led to formation of the 3-amino derivatives of 2 and the corresponding desoxy products 3. The latter were also obtained by an independent method by heating 3-chloro-6,8-dimethylpyrimido[4,5-c]pyridazine-5,7(6H,8H)-dione with alkylamines in butanol.     

Synthesis of a New Heterocyclic System. 7-Methyl-1-phenyl-5,7-dihydro[1,2]diazepino[5,4-b]carbazol-4(3H)-one

Russian Journal of Organic Chemistry - 7-Methyl-1-phenyl-5,7-dihydro[1,2]diazepino[5,4-b]carbazol-4(3H)-one representing a new heterocyclic system has been synthesized starting from...     

Facile and efficient synthesis of 5,7-disubstituted thiazolo[5,4-d] pyrimidine-4,6(5H,7H)-diones

A facile and efficient approach was developed to access 5,7-disubstitued thiazolo[5,4-d]pyrimidine-4,6(5H,7H)-diones through condensation of N-substituted 5-amino-4-carbethoxythiazole with structurally diverse isocyanates in the presence of sodium hydride.The easy availability of substrates and tolerance of structural diversity in this reaction make it attractive to be used for construction of libraries in drug discovery process.     

Lactam and acid amide acetals 65. Study of the reaction of DMF diethylacetal with 5-carbamoyl(thiocarbamoyl)-6-aminopyrrolizine derivatives

The reaction of DMF diethylacetal with 5-carbamoyl(thiocarbamoyl)-6-aminopyrrolizine derivatives proceeds regioselectively at the amido (thioamido) group without involving the 5-amino group. The synthesized acyl(thioacyl)amidines are starting compounds in the production of pyrimido[5,4-e]pyrrolizine derivatives.See [1] for Communication 64.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 349–354, March, 1991.     

Synthesis of 4-hydrazino-5H-pyrimido[5,4-b]indole and related compounds

This paper describes the synthesis of two 4-amino-5H-pyrimido[5,4-b]indoles 5 , 4-hydrazino-5H-pyrimido[5,4-b]indole 6 , two 1,2,4-triazolo[4,3-c]pyrimido[5,4-b]indoles 8 , and tetrazolo[4,5-c]pyrimido[5,4-b]indole 10 . Starting with ethyl 3-aminoindole-2-carboxylate 1 , 5H-pyrimido[5,4-b]indol-4-one 2 was obtained (80%) by condensing with formamide. Reactions of 2 with phosphorus oxychloride and phosphorus pentasulfide gave respectively, 4-chloro-5H-pyrimido[5,4-b]indole 3 (70%) and 5H-pyrimido[5,4-b]indole-4-thione 4 (80%). Compound 3 reacted with amines (morpholine, piperidine) to give the respective 4-amino-5H-pyrimido[5,4-b]-indoles 5 , and compound 4 reacted with hydrazine to give 4-hydrazino-5H-pyrimido[5,4-b]indole 6 (80%). Two hydrazones of 6 (benzylidene, isopropylidene) 7 were also prepared (90%). Compound 6 reacted with formic and acetic acids to give (65–75%) the respective 1,2,4-triazolo[4,3-c]pyrimido[5,4-b]indoles 8 and with nitrous acid to give tetrazolo[4,5-c]pyrimido[5,4-b]indole 9 (85%). All the new compounds 2 to 9 were characterized by elemental analysis and spectral data (ir, nmr).     

Synthesis and applications of [1-(15)N]-labeled 4,6-dimethyl-4H-[1,2,5]oxadiazolo[3,4-d]pyrimidine-5,7-dione 1-oxide as a useful tool for mechanistic investigations

[1-(15)N]-Labeled 4,6-dimethyl-4H-[1,2,5]oxadiazolo[3,4-d]pyrimidine-5,7-dione 1-oxide (1-(15)N1) was easily prepared by nitration of commercially available 6-amino-1,3-dimethyl-1H-pyrimidine-2,4-dione using 15N-enriched nitric acid followed by an intramolecular oxidative cyclization with iodosylbenzene diacetate under mild conditions. On the basis of the experimental results using 1-(15)N1, the formation of 8-phenyltheophylline (3), the 1,3-dimethylalloxazines (4: n = 0, 1), and 1,3,7,9-tetramethyl-1H,9H-pyrimido[5,4-g]pteridine-2,4,6,8-tetraone++ + (5) in the thermal reaction of the N-oxide 1 with benzylamine, aniline, or piperidine, and the generation of NO or NO-related species in the reaction with N-acetylcysteamine were reasonably explained by considering the initial attack of the employed nucleophiles on the 3a-position of 1.     

Application of bis(iminophosphorane) in heterocyclic synthesis: new entries to symmetrically or unsymmetrically substituted thieno[2,3-d:5,4-d']dipyrimidine-4,5(3H,6H)-diones

The bis(carbodiimides) 4, obtained from bis-aza-Wittig reactions of bis(iminophosphorane) 3 with 2 equiv of aromatic isocyanates, were reacted with secondary amine to give symmetrically substituted 2,7-diaminothieno[2,3-d:5,4-d']dipyrimidine-4,5(3H,6H)-dione 6 in the presence of a catalytic amount of EtO(-)Na(+). Reactions of 4 with phenols or ROH in the presence of a catalytic amount of potassium carbonate or RO(-)Na(+) gave symmetrically substituted 2,7-diaryl(alkyl)oxythieno[2,3-d:5,4-d']dipyrimidine-4,5(3H,6H)-diones 6 in satisfactory yields. However, iminophosphoranes 9 were obtained via reaction of bis(iminophosphorane) 3 with 1 equiv of aromatic isocyanate and subsequent reaction with an amine in the presence of a catalytic amount of EtO(-)Na(+). Further reaction of iminophosphoranes 9 with aromatic isocyanates and various nucleophile generated unsymmetrically substituted thieno[2,3-d:5,4-d']dipyrimidine-4,5(3H,6H)-diones 12 in good yields.     

Synthesis, molecular structure and characterization of allylic derivatives of 6-amino-3-methyl-1,2,4-triazolo[3,4-f][1,2,4]-triazin-8(7H)-one

1-Allyl- (2) and 7-allyl-6-amino-3-methyl-1,2,4-triazolo[3,4-f][1,2,4]triazin-8(7H)-one (3) were obtained via the 18-crown-6-ether catalyzed room temperature reaction of 6-amino-3-methyl-1,2,4-triazolo[3,4-f][1,2,4]triazin-8(7H)-one (1) with potassium carbonate and allyl bromide in dry acetone. The structures of these two derivatives were verified by 2D-NMR measurements, including gHSQC and gHMBC measurements. The minor compound 2 may possess aromatic character. A single crystal X-ray diffraction experiment indicated that the major compound 3 crystallizes from dimethyl sulfoxide in the monoclinic space group P2(1)/n and its molecular structure includes an attached dimethylsulfoxide molecule, resulting in the molecular formula C(10)H(16)N(6)O(2)S. Molecular structures of 3 are linked by extensive intermolecular N-H...N hydrogen bonding [graph set C(1)(1)(7)]. 1 Each molecule is attached to the dimethyl sulfoxide oxygen via N-H...O intermolecular hydrogen bonding. The structure is further stabilized by pi-pi stacking interactions.     

Studies with Heterocyclic β‐Enaminoniriles: A Simple Route for the Synthesis of Polyfunctionally Substituted Thiophene,Imidazo[1,2:1′,6′]pyrimido[5,4‐b]thiophene and Thieno[3,2‐d]pyrimidine Derivatives

Reaction of 3,5‐diaminothiophene‐2‐carbonitrile derivatives 3a‐c with ethoxycarbonylmethyl isothiocyanate and/or N‐[bis(methylthio)methylene]glycine ethyl ester led to formation of 7‐substituted‐8‐amino‐5‐thioxo‐6H‐imidazo[1,2:1′,6′]pyrimido[5,4‐b]thiophene‐2(3H)‐one derivatives 6a‐c and 7‐substituted‐8‐amino‐5‐(methylthio)imidazo[1,2:1′,6′]pyrimido[5,4‐b]thiophene‐2(3H)‐one 7a‐c , respectively. Also, the synthetic potential of the β‐enaminonitrile moiety in 3a‐c has been explored; it proved to be a promising candiate for the synthesis of 1,6‐disubstituted‐2,4‐diamino‐7,8‐dihydro‐8‐oxopyrrolo[1,2‐a]thieno[2,3‐e]pyrimidine derivatives 10a‐f and pyrido[2′,3′:6,5]pyrimido[3,4‐a]benzimidazole derivatives 12a,b .     

Regioselective synthesis of novel N2- and N4-substituted 7-methylpyrazolo[4,5-e][1,2,4]thiadiazines

The new compound 7-methylpyrazolo[4,5-e][1,2,4]thiadiazin-3(2H,4H)-one1,1-dioxide (5) was synthesized and its novel mono N2- or N4-substituted derivatives 6 and 7 were prepared by regioselective N-alkylation of 5 with different molar ratios of NaH and alkyl halides. Based on the regioselective alkylation conditions found a facile one-pot synthesis of N2,N4-disubstituted pyrazolo[4,5-e][1,2,4] thiadiazines 8 was developed. The structures of the newly synthesized compounds were confirmed by IR,(1)H-NMR, (13)C-NMR and MS spectral analysis.