Regioselective Synthesis of 2-Substituted [1,2,4]Triazolo[5,1-b][1,3]thiazin-7-ones by Heteropolyacids

2-Substituted [1,2,4]triazolo[5,1-b][1,3]thiazin-7-ones 3 were synthesized via regioselective cyclization of 4H-[1,2,4]triazol-3-ylsulfanyl-acrylic acids 2 in the presence of catalytic amounts of heteropolyacids at room temperature in very good yields and rates.     

Efficient Synthesis of Fluorinated [1,2,4]Triazolo[3,4-b][1,3,4]thiadiazoles

Russian Journal of Organic Chemistry - An efficient synthesis of fluorinated [1,2,4]triazolo[3,4-b][1,3,4]thiadiazole derivatives has been achieved by cyclocondensation of 5-substituted...     

Sulfuric Acid: A Mild Catalyst for the Regioselective Synthesis of 2-Substituted [1,2,4]Triazolo[5,1-b][1,3]thiazin-7-ones

Summary.  A facile and regioselective synthesis of 2-substituted [1,2,4]triazolo[5,1-b][1,3]thiazin-7-ones by action of sulfuric acid on (4H-[1,2,4]triazol-3-ylsulfanyl)-acrylic acids is described. Received January 23, 2001. Accepted (revised) May 7, 2001     

Synthesis and chemical transformations of partially hydrogenated [1,2,4]triazolo[5,1-b]quinazolines

The reaction of 5-methyl-7-phenyl-4,7-dihydro-1,2,4-triazolo[1,5-a]pyrimidine with α,β-unsaturated carbonyl compounds in MeOH in the presence of MeONa affords partially hydrogenated aryl-substituted [1,2,4]triazolo[5,1-b]quinazolines. Hydrolysis, oxidation, reduction, and alkylation of 5,6,8-triphenyl-5,6,7,10-tetrahydro[1,2,4]triazolo[5,1-b]quinazoline were studied. The structure of one oxidation product, viz., 7-hydroxy-5,6,8-triphenyl-6,7-dihydro[1,2,4]triazolo[5,1-b]quinazoline, was established by X-ray diffraction. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 335—340, February, 2006.     

新型[1,2,4]三唑[4,3-b]均四嗪类化合物的合成及其抗癌活性

以6-(3,5-二甲基吡唑-1-基)-3-肼基均四嗪和芳醛为原料,经Schiff碱缩合和环合反应合成了6个新型的6-芳基-3-(3,5-二甲基吡唑-1-基)[1,2,4]三唑[4,3-b]均四嗪类化合物(4a～4f),其结构经1HNMR,MS,IR和元素分析表征。以顺铂为对照,采用MTT法测试了体外4a～4f对人白血病细胞株,人肺癌,人乳腺癌和人子宫颈癌细胞株的抗癌活性。结果表明,4a～4f对四种癌细胞均具有较强的抑制活性。     

Synthesis and Tautomeric Structure of 7-Arylhydrazono-7H-[1,2,4]Triazolo[3,4-b][1,3,4]Thiadiazines

Two synthetic approaches were developed for the title compounds 8a-g via coupling of diazotized anilines with 7-acetyl-6-methyl-3-phenyl-7H-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazine 7 , and reaction of N-aryl 2-oxopropanehydrazonoyl chlorides 9 with 4-amino-3-mercapto-5-phenyl-1,2,4-triazole 1 . The tautomeric structures of 8 were elucidated by their spectral analyses and correlation of their acid dissociation constants with Hammett equation.     

Synthesis of New Phosphonate Derivatives of Naphtho[2,1-b[Pyran]3,2-e][1,2,4]Triazolo [1,5-c]Pyrimidines

Abstract

The synthesis of new naphthopyranotriazolopyrimidines phosphonates 4a–i in good yields (74%–93%) has been accomplished via Michaelis–Arbusov rearrangement by the reaction of trialkyl phosphite with naphthopyranotriazolopyrimidines chloride 3a–e, which were obtained from α-functionalized iminoethers 1 in two steps. The synthesized compounds 4a–i were completely characterized by IR, ¹H, ¹³C, and ³¹P NMR and HRMS.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

Synthesis of 9-Aryl-6,6-dimethyl-5,6,7,9-tetrahydro-1,2,4-triazolo[5,1-b]quinazolin-8(4H)ones

The reaction of 3-amino-1,2,4-triazole with arylidene derivatives of dimedone and their potential synthetic equivalents leading to the formation of 9-aryl-6,6-dimethyl-5,6,7,9-tetrahydro-1,2,4-triazolo[5,1-b]quinazolin-8(4H)ones has been studied. The direction of heterocyclization has been established, and the possible mechanisms for the formation of the pyrimidine heterocycle have been analysed.     

Synthesis and Antimicrobial Study of New Fused Thiazolo[3,2-b]triazine,Triazolo[4,3-b]triazine,and 1,2,4-Triazinone Derivatives

Russian Journal of Organic Chemistry - 6-[2-(Furan-2-yl)ethyl]-3-sulfanylidene-3,4-dihydro-1,2,4-triazin-5(2H)-one (1) reacted with chloroacetone to give S-acetonyl derivative which cyclized in...     

新型三环系稠杂环[1,2,4]-三唑并[1,5-a][1]-苯并氮杂(艹卓)及[1,2,4]-三唑并[1,5-a]-喹啉的合成

α-四氢萘酮的乙氧羰基腙(1)经LTA氧化, 得到α-偶氮-α-乙酰氧基化合物2. 在AlCl3作用下, 化合物2脱去乙酰氧基产生重氮正离子中间体3, 再经与腈的1,3-偶极环加成、 [1,2]-迁移扩环、碱性水解和与苦味酸作用, 得到新型[1,2,4]-三唑并[1,5-a][1]苯并氮杂(艹卓)苦味酸盐6a～6c. 以2,3-二氢-1-茚酮为底物, 采用相同的合成路线, 合成了1,2,4-三唑并[1,5-a]-二氢喹啉苦味酸盐12a～12c.     

Synthesis of substituted imidazo[5,1-b]benzimidazoles

Some chemical characteristics and reactions of 3-phenyl-4-methylimidazo[5,1-b]benzimidazole (I) have been examined. It has been shown that I undergoes electrophilic substitution (hydroxymethylation, acetylation, nitrosation, and the Mannich and Vilsmeier reactions), the substituent entering at the 1-position. Cyanoethylation of I gives 1-cyanoethyl-3-phenyl-4-methylimidazo[5,1-b]benzimidazole.For part III, see [3].     

Design,Synthesis, and Antimicrobial Evaluation of Novel [1,2,4]Triazolo[3,4-b][1,3,4]thiadiazepine Derivatives

Russian Journal of Organic Chemistry - The title compounds,...     

新型三环系稠杂环[1,2,4]-三唑并[1,5-a][1]-苯并氮杂及[1,2,4]-三唑并[1,5-a]-喹啉的合成

α-四氢萘酮的乙氧羰基腙(1)经LTA氧化,得到α-偶氮-α-乙酰氧基化合物2.在A lC l3作用下,化合物2脱去乙酰氧基产生重氮正离子中间体3,再经与腈的1,3-偶极环加成、[1,2]-迁移扩环、碱性水解和与苦味酸作用,得到新型[1,2,4]-三唑并[1,5-a][1]苯并氮杂苦味酸盐6a~6c.以2,3-二氢-1-茚酮为底物,采用相同的合成路线,合成了1,2,4-三唑并[1,5-a]-二氢喹啉苦味酸盐12a~12c.     

Multicomponent Efficient Synthesis of New [1,2,4]Triazolo[3,4]thiadiazines

A series of novel triazolo thiadiazines were synthesized by a simple, highly efficient, one‐pot pseudo four component approach involving the condensation of 4‐amino‐5‐hydrazinyl‐4H‐1,2,4‐triazole‐3‐thiol ( 1 ), aromatic aldehydes ( 2 ), and various phenacyl bromides ( 3 ) with good yields. The structures of compounds were confirmed by analytical and spectral (IR, ¹H NMR, ¹³C NMR) data.     

Synthesis of 8-alkylthio- and 8-selanyl-3-tert-butylpyrazolo[5,1-c][1,2,4]triazines

Abstract

Interaction of 8-lithio-3-tert-butyl-4-oxopyrazolo[5,1-c][1,2,4]triazin-1-ide with elemental sulfur or selenium in THF with further in situ alkylation at –97?°C followed by warming to room temperature furnished a series of 3-tert-butyl-8-X-pyrazolo[5,1-c][1,2,4]triazin-4(6H)-ones (X?=?n-BuS, n-BuSe, MeSe, PhCH₂S) in good yields. 8,8'-Diselanediylbis(3-tert-butylpyrazolo[5,1-c][1,2,4]triazin-4(1H)-one) was also isolated as a by-product in these reactions. One-pot interaction of the n-BuSe substituted derivative with diborane/boron trifluoride led to reduction of the 1,2,4-triazine core and partial elimination of the alkylselanyl moiety. The structures of the synthesized products were established on the basis of IR, ¹H, 13C, 2D HMBC ¹H–⁷⁷Se NMR and high resolution mass spectra, as well as X-ray single crystal diffraction analyses. Two of the prepared compounds were also tested for antimicrobial and antifungal activities.     

A Facile and Efficient Synthesis of Novel 1,2,4-Triazolo[5,1-b]quinazolin-9-one Derivatives

Summary.  A facile and efficient synthesis of a series of novel 1,2,4-triazolo[5,1-b]quinazolines is described. 2,3-Diaryl-2,3-dihydro-1H-1,2,4-triazolo[5,1-b]quinazolin-9-ones were obtained by reaction of 3-amino-2-arylamino-3H-quinazolin-4-ones with aromatic aldehydes as well as by ring closure of the corresponding anils. Treatment of 3-amino-2-arylamino-3H-quinazolin-4-ones with aromatic carboxylic acids afforded 2,3-diaryl-3H-1,2,4-triazolo[5,1-b]quinazolin-9-ones which could also be synthesized by dehydrogenation of the corresponding dihydro derivatives. Reaction of 3-amino-2-arylamino-3H-quinazolin-4-ones with diethyl malonate and acetylacetone gave 3-aryl-3,9-dihydro-9-oxo-1,2,4-triazolo[5,1-b]quinazolin-2-yl-acetic acid ethyl ester and 3-aryl-2-methyl-3H-1,2,4-triazolo[5,1-b]quinazolin-9-ones, respectively. The latter compounds were also prepared via reaction with acetic anhydride, whereas acetylation with acetic anhydride in the presence of pyridine afforded the acetyl derivatives. Received March 22, 2001. Accepted (revised) May 11, 2001