Synthesis of 6-mono- and 5,6-disubstituted 1,2,3-triazolo[4,5-d]pyrimidin-7-ones

The reactions of N-substituted 4-amino-3-benzyl-1,2,3-triazole-5-carboxamides with phosphorus oxochloride and dimethylformamide at 80 °C or with triethyl orthoacetate and acetic anhydride at 160 °C afforded 6-mono- or 5,6-disubstituted 1,2,3-triazolo[4.5-d]pyrimidin-7-ones in 30—85% and 65—90% yields, respectively.     

Iminophosphorane-mediated efficient synthesis of new tricyclic 3,5-dihydro-1,2,3-triazolo[4,5-d]-1,2,4-triazolo[1,5-a]pyrimidin-9-ones

The carbodiimides 2, obtained from aza-Wittig reactions of iminophosphorane 1 with aromatic isocyanates, reacted with hydrazine to give selectively 6-amino-7H-1,2,3-triazolo[4,5-d]pyrimidin-7-ones 5. Compounds 5 were further transformed to iminophosphoranes 6 by reaction with triphenylphosphine, hexachloroethane and triethylamine. A tandem aza-Wittig reaction of iminophosphorane 6 with isocyanate or acyl chloride generated previously unreported 3,5-dihydro-1,2,3-triazolo[4,5-d]-1,2,4-triazolo[1,5-a]pyrimidin-9-ones 10 or 12 in satisfactory yield. X-ray structure analysis of 10 g verified the proposed structure and the reaction selectivity.     

Synthesis and Crystal Structure of 3-Benzyl-5-cyclohexylamino-6-phenyl-3,6-dihydro-1,2,3-triazolo[4,5-d]pyrimidin-7-one

1 INTRODUCTION A large number of 8-azapurine (1,2,3-triazolo[4,5-d]pyrimidine) derivatives have been synthe-sized in recent years, and many of them are reportedto exhibit broad spectral biological activities, such asthe interesting antifungal[1], antiviral[2], anticancer[3]and antiallergic[4] properties. So far, these compoundshave been prepared by either of the following twomajor routes: annulation of a triazole ring onto apyrimidine ring or a pyrimidine ring onto a triazolering. Mos…     

Microwave assisted synthesis of 2,3-dihydro-4H-benzo[4,5]thiazolo[3,2-a]furo[2,3-d]pyrimidin-4-ones and 6,7-dihydro-5H-furo[2,3-d]thiazolo[3,2-a]pyrimidin-5-ones using Mn(OAc)3

2-Hydroxy-4H-benzo[4,5]thiazolo[3,2-a]pyrimidin-4-one 2a and 7-hydroxy-5H-thiazolo[3,2-a]pyrimidin-5-one 2b, were obtained in high yields under mild conditions from the cyclization reactions of bis-(2,4,6-trichlorophenyl) malonate and 2-aminobenzothiazole or 2-aminothiazole, respectively. A new class of compounds, 2,3-dihydro-4H-benzo[4,5]thiazolo[3,2-a]furo[2,3-d]pyrimidin-4-ones and 6,7-dihydro-5H-furo[2,3-d]thiazolo[3,2-a]pyrimidin-5-ones, were synthesized via the microwave assisted radical addition of compounds 2a and 2b to various alkenes using manganese(III) acetate. A preliminary acetylcholine esterase (AchE) inhibition test of compound 4e showed excellent (92%) inhibitory potential, comparable with the standard drug Donapezil®.     

A Solution-Phase Parallel Synthesis of 5-Substituted 3,6-Dihydro-7H-1,2,3-triazolo[4,5-d]pyrimidin-7-ones

5‐Substituted 7H‐1,2,3‐triazolo[4,5‐d]pyrimidin‐7‐ones ( 4 ) were rapidly prepared by a solution‐phase parallel synthetic method, which includes aza‐Wittig reaction of iminophosphorane ( 1 ) with phenyl isocynate to give carbodiimide ( 2 ) and subsequent reaction of 2 with various amine and alcohols in the presence of catalytic amount of sodium alkoxide in a parallel fashion.     

Synthesis of [1,2,3]Triazolo[4,5-d]pyrimidine 3-Oxides

[1,2,3]Triazolo[4,5-d]pyrimidine 3-oxides were synthesized by replacement of the amino group in 6-aminouracil by hydroxyamino, coupling of the resulting 6-hydroxyaminopyrimidine with benzenediazonium salts, and oxidation of 6-hydroxyamino-5-phenylazouracils with a solution of K₃[Fe(CN)₆] in water.     

Reaction of 6-arylidenehydrazino-1,3-dimethyluracils with thionyl chloride leading to purine,thiazolo[4,5-d]pyrimidine,pyrimido[4,5-e][1,3,4]thiadiazine,pyrazolo[3,4-d]pyrimidine,and [1,2,3]thiadiazolo[4,5-d]pyrimidine derivativese

The reaction of 6-arylidenehydrazino-1,3-dimethyluracils with thionyl chloride in benzene afforded purine, thiazolo[4,5-d]pyrimidine, pyrimido[4,5-e][1,3,4]thiadiazine, pyrazolo[3,4-d]pyrimidine, and [1,2,3]thiadiazolo[4,5-d]pyrimidine derivatives, while the treatment of 6-(benzylidene-1′-methylhydrazino)-1,3-dimethyluracil with thionyl chloride in benzene gave 4-methylpyrimido[4,5-e][1,3,4]thiadiazine and 1-methylpyrazolo-[3,4-d]pyrimidine derivatives. Plausible mechanisms for the formation of these fused pyrimidines are also described.     

新型[1,2,3]三唑-[4,5-d]嘧啶酮类衍生物的微波法合成

以卤代烃、邻甲基苯胺、氰基乙酸和乙酰氯为原料,经取代、成环、偶联和关环4步反应,用微波法合成了9个[1,2,3]三唑-[4,5-d]嘧啶酮类衍生物（5a~5i）,其中5a~5e, 5g和5i为新化合物,其结构经¹H NMR, ¹³C NMR和HR-MS(ESI)表征。     

1,2,3-Triazolo[4,5-d]-1,2,4-triazolo[4,3-b]pyridazines

Some new 1,2,3-triazolo[4,5-d]-1,2,4-triazolo[4,3-b]pyridazines were prepared starting from the corresponding 1,2,3-triazolo[4,5-d]pyridazines via the formation of the 1,2,4-triazole ring, by condensation of an appropriate monocarbon fragment with the 4-hydrazino substituent and the nitrogen atom in the 5 position of the heterocycle. Condensation of 4-phenylhydrazino substituted derivatives with formic acid gave zwitterionic compounds.     

v-Triazolines. Part XIX. Thiocino[4,5-d]-1,2,3-triazole and thiocino[4,5-d]isoxazole derivatives

5-Amino-2,3,6,7-tetrahydrothiocines were reacted with arylazides yielding 1-aryl-9a-amino-1,3a,4,5,7,8,9,9a-octahydrothiocino[4,5-d]-1,2,3-triazoles which could be deaminated to 1-aryl-1,4,5,7,8,9-hexahydrothiocino-[4,5-d]-1,2,3-triazoles. Similarly, the above enamines yielded, with nitrile oxides, 3-aryl-9a-amino-3a,4,5,8,9,9a-hexahydrothiocino[4,5-d]isoxazoles which were transformed with acids into 3-aril-4,5,8,9-tetrahydrothiocino-[4,5-d]isoxazoles.     

Synthesis of 3-alkyl-5-arylamino-6,11-dihydro-3H-anthra[1,2-d]-[1,2,3]triazole-6,11-dione 2-oxides by nitrosation of 3-alkylamino-5-arylamino-6H-anthra[1,9-cd]isoxazol-6-ones

Nitrosation of 3-alkylamino-5-arylamino-6H-anthra[1,9-cd]isoxazol-6-ones with sodium nitrite in acetic acid leads to the formation of the corresponding unstable N-nitroso derivatives which are converted into 3-alkyl-5-arylamino-6,11-dihydro-3H-anthra[1,2-d][1,2,3]triazole-6,11-dione 2-oxides on heating.     

Synthesis of some isomeric 4,11-dihydro-5H-[1]benzoxocino[4,3-d] or [3,4-c]isoxazol-5-ones and isomeric 4,5,10,11-tetrahydrobenzo[5,6]-cycloocta[2,1-d] or [1,2-c]isoxazol-5-ones

The title compounds were prepared by acid-catalyzed cyclization of aryloxymethyl- or (2-arylethyl)-4-carboxymethylisoxazoles which in turn were synthesized from aryloxymethyl- or (2-arylethyl)isoxazole-4-carboxylic acids by Arndt-Eistert homologation.     

Synthesis of novel 5-piperidyl-substituted 7-hydroxy-3H-1,2,3-triazolo[4,5-d]pyrimidines

A series of 8-azapurin-6-ones having a piperidine substituent at position 5 has been synthesized from pipecolinate esters, benzylazides, and cyanoacetamide. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 276–290, February, 2006.     

Fused Diazepines. Synthesis of 2-Methyl-8-aryl-4,6-dihydro-5H-thieno[3',2':4,5]thieno[2,3-d][1,2]diazepin-5-ones

Russian Journal of Organic Chemistry - Heterocyclization of ethyl 2-acetyl(aroyl)-5-methylthieno[2,3-b]thiophene-3-acetates with hydrazine hydrate has been studied. A dependence of the reaction...     

Efficient synthesis of 5-substituted-4,5-dihydro-1,2,4-triazin-6-ones and 5-substituted-1,2,4-triazin-6-ones

Treatment of methyl α-(dimethylarninomethyleneamino)carboxylates 1 (from α-amino acids and dimethylformamide dimethylacetal) with hydrazine gives 5-substituted-4,5-dihydro-1,2,4-triazin-6-ones 2 , which are smoothly dehydrogenated to 5-substituted-1,2,4-triazin-6-ones 3 with potassium permanganate in acetone/acetic acid.     

Synthesis of aminomethyl derivatives of 3-methyl-4,7-dihydro-3H-imidazo[4,5-d][1,2,3]triazin-4-one

New aminomethyl derivatives of 3-methyl-4,7-dihydro-3H-imidazo[4,5-d][l,2,3]triazin-4-one were synthesized by Mannich reaction. These Mannich bases is also possible to prepare by reaction of 7(5)-hydroxymethyl-3-methyl-4,7(5)dihydro-3H-imidazo[4,5-d][l,2,3]triazin-4-one with amines. The compounds obtained exist in solutions as mixtures of N⁵ and N⁷ isomers, and the fraction of the latter grows with the polarity of the solvent.     

Synthesis of 6H-Naphtho[1,2,3-cd]indol-6-ones

S,S-Dimethyl-and S-methyl-S-phenyl-N-(9,10-anthraquinon-1-yl)sulfoximides are converted into 6H-naphtho[1,2,3-cd]indol-6-ones on heating in polar aprotic solvents.