Structure and properties of 1- and 3-hydroxytriazolo [4,5-b] pyridines

It is shown that 1-hydroxytriazolo[4,5-b]pyridine exists in alcohol solution primarily in the N-oxide form, whereas 3-hydroxytriazolo[4,5-b]pyridine exists in the hydroxy form. 4-Methyl-triazolo[4,5-b]pyridine 1-oxide is formed in the methylation of 1-hydroxytriazolo[4,5-b]pyridine, whereas 3-methoxytriazolo[4,5-b]pyridine is formed in the methylation of 3-hydroxytriazolo[4,-5-b]pyridine.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1418–1421, October, 1976.     

A concise synthesis of all four possible benzo[4,5]furopyridines via palladium-mediated reactions

[reaction: see text] By taking advantage of the alpha- and gamma-activation of chloropyridines as well as palladium-mediated reactions, all four possible benzo[4,5]furopyridine tricyclic heterocycles, benzo[4,5]furo[2,3-b]pyridine, benzo[4,5]furo[2,3-c]pyridine, benzo[4,5]furo[3,2-c]pyridine, and benzo[4,5]furo[3,2-b]pyridine, are efficiently synthesized from 2-chloro-3-iodopyridine, 3-chloro-4-stannylpyridine, 4-chloro-3-iodopyridine, and 2-chloro-3-hydroxypyridine, respectively.     

咪唑并吡啶类化合物的合成及其应用*

咪唑并吡啶类化合物具有与吲哚、氮杂吲哚等类似的特殊结构和良好的生物活性,在医药和农药工业有着广泛的应用,成为有机化学家和药物化学家的研究热点。咪唑并吡啶类化合物主要有咪唑并[4,5-b]吡啶、咪唑并[4,5-c]吡啶、咪唑并[1,2-a]吡啶和咪唑并[1,5-a]吡啶等4个类型。本文阐述了近年来咪唑并吡啶类化合物的合成研究进展和应用情况,主要介绍了咪唑并[4,5-b]吡啶和咪唑并[4,5-c]吡啶这两类化合物的合成方法和在医药及农药领域的应用。     

Quantum chemical predictions concerning two unknown “mesoionic” compounds

The Pariser-Parr-Pople approximation was used to predict the properties of compounds I, 3-oxo-2H-1,2,3-triazolo[3,4-a]pyridine, and II, 3-oxoisoxazolo[2,3-a]pyridine, originated by joining a pyridine ring to two sydnone-like heterocyclic systems not yet reported in the literature. A parallel computation was carried out for two known compounds of similar structure, to give the predictions a better reliability through the comparison with observed spectral data and chemical behaviour. Compound I is expected to be stable, with an absorption spectrum similar to III, 2-oxo-1,3,4-oxadiazolo[4,5-a]pyridine, and chemical properties analogous to IV, 1-methyl-3-oxo-1,2,4-triazolo-[4,3-a]pyridine. A reaction path is suggested for obtaining from I the unknown isomeric structure V, 3-oxo-1H-1,2,3-triazolo[3,4-a]pyridine. Compound II is predicted as an unstable orange-red substance which should be handled and kept at low temperatures.     

Synthesis and Reactions of Some New Oxazolo[4,5-b]Pyridines and Related Compounds

A series of 2-heterocyclicalkylthiooxazolo[4,5-b]pyridines have been prepared through the reaction of 2-(hydrazinocarbomethylthio)oxazolo[4,5-b]pyridine with the appropriate reagents. 2-Ethylthiooxazolo[4,5-b]pyridine has been successfully employed to synthesize some fused- triheterocyclic compounds.     

A comparison of two methods for the preparation of 3-Deazapurine ribonucleosides

The reaction of the trimethylsilyl derivative of 4,6-dichloroimidazo[4,5-c]pyridine with 2,3,5-tri-O-benzoyl- D -ribofuranosyl bromide gave four nucleosides-the α- and β-anomers of the 1-isomer and the α- and β-anomers of the 3-isomer (3.9:2.7:1.5:1). In contrast, the fusion reaction of 4,6-dichloroimidazo[4,5-c ]pyridine with 1,2,3,5-tetra-O-acetyl-β- D -ribofuranose gave a high yield of the 1-β-isomer, which was converted to the known 3-deazaadenosine (4-amino-l-β- D -ribofuranosylimidazo[4,5-c]pyridine).     

Synthetic studies of potential antimetabolites. XIII. Synthesis of 7-amino-3-β-d-ribofuranosyl-3H-imidazo[4,5-b] pyridine (1-deazaadenosine) and related nucleosides

7-Amino-3-β-D-ribofuranosyl-3H-imidazo[4,5-b]pyridine (III, 1-deazaadenosine) was synthesized in 32% yield from the diacetyl derivative prepared from 7-aminoimidazo[4,5-b ]pyridine (1-deazaadenine) and 1,2,3,5-tetra-O-acetyl-β-D-ribose by the fusion method. A synthesis of 7-amino-4-b?-D-ribofuranosyl-4H-imidazo[4,5-b]pyridine (IV) was also achieved.     

Synthesis and Anticancer Evaluation of 2-{4-[5-(5-Substituted arylpyrimidin-2-yl)-1H-pyrazol-3-yl]-phenyl}thiazolo[4,5-b]pyridine Derivatives

Russian Journal of General Chemistry - In the present study a new series of 2-{4-[5-(5-substituted arylpyrimidin-2-yl)-1H-pyrazol-3-yl] phenyl}thiazolo[4,5-b]pyridine derivatives (11a–11j)...     

Design,Synthesis of New 1,2,4-Triazole/1,3,4-Thiadiazole with Spiroindoline,Imidazo[4,5-b]quinoxaline and Thieno[2,3-d]pyrimidine from Isatin Derivatives as Anticancer Agents

The current work aims to design and synthesis a new series of isatin derivatives and greatly enhances their cytotoxic activity. The derivatives 3-((bromophenyl) imino)-1-(morpholino (pyridine) methyl) indolin-2-one, 2-((oxoindoline) amino) benzoic acid, 3-(thiazolo-imino) indolinone, ethyl-2-((oxoindolin-3-ylidene)amino)-benzothiophene-3-carboxylate, 1-(oxoindoline)-benzo[4,5] thieno [2,3-d]pyrimidin-4(1H)-one, ethyl-2-(2-oxoindoline) hydrazine-1-carboxylate, N-(mercapto-oxo-pyrimidine)-2-(oxoindoline) hydrazine-1-carboxamide, N-(oxo-thiazolo[3,2-a] pyrimidine)-2-(oxoindolin-ylidene) hydrazine-carboxamide, 3-((amino-phenyl) amino)-3-hydroxy- indolinone, 3-((amino-phenyl) imino)-indolinone, 2-(2-((oxoindoline) amino) phenyl) isoindolinone, 2-(oxoindoline) hydrazine-carbothioamide, 5′-thioxospiro[indoline-3,3′-[1,2,4]triazolidin]-one, 5′-amino-spiro[indoline-3,2′-[1,3,4]thiadiazol]-2-one and 3-((2-thioxo-imidazo[4,5-b]quinoxaline) imino) indolinone were synthesized from the starting material 1-(morpholino (pyridine) methyl) indoline-2,3-dione and evaluated for their in vitro cytotoxic activity against carcinogenic cells. The new chemical structures were evidenced using spectroscopy (IR, NMR and MS) and elemental analysis. The results show that compounds imidazo[4,5-b]quinoxaline-indolinone, thiazolopyrimidine-oxoindoline, pyrimidine-oxoindoline-hydrazine-carboxamide, spiro[indoline-3,2′-[1,3,4] thiadiazol]-one and spiro[indoline-3,3′-[1,2,4]triazolidin]-one have excellent anti-proliferative activities against different human cancer cell lines such as gastric carcinoma cells (MGC-803), breast adenocarcinoma cells (MCF-7), nasopharyngeal carcinoma cells (CNE2) and oral carcinoma cells (KB).     

First Synthesis of 5-Chloro-7-[1,3]oxazolo[4,5-b]pyridin-2-ylquinolin-8-ol by Pd-Catalyzed Arylation

5-Chloro-7-[1,3]oxazolo[4,5-b]pyridin-2-ylquinolin-8-ol was synthesized by a Pd-catalyzed arylation, which proceeds efficiently with 2 equivalents of benzylated clioquinol and 1 equivalent of oxazolo[4,5-b]pyridine. The product was smoothly debenzylated by boron trichloride in dichloromethane.     

Co-synthesis of 1-(3-aminopyridin-2-yl)-1H-benzimidazole and 3-(2-aminophenyl)-3H-imidazo[4,5-b]pyridine

Russian Chemical Bulletin - A new method for the synthesis of N-substituted 3H-imidazo[4,5-b]pyridine via chemical reduction of 1-(3-nitropyridin-2-yl)-1H-benzimidazole in an acidic media was...     

Regioselective synthesis of C-2 substituted imidazo[4,5-b]pyridines utilizing palladium catalysed C–N bond forming reactions with enolizable heterocycles

In this Letter we report a rapid and facile access to C2-substituted imidazo[4,5-b]pyridine analogues utilizing palladium mediated Buchwald–Hartwig cross-coupling reactions. The use of enolizable heterocycles as cross-coupling partners resulted in a wide range of imidazo[4,5-b]pyridine analogues which are prone to have medicinal relevance. Xantphos and Pd(OAc)₂ were found to be more effective for the coupling of 2-halo imidazo[4,5-b]pyridines with pyridone nucleophiles. A regioselective approach for the synthesis of 2-substituted 3H-imidazo[4,5-b]pyridine and 1H-imidazo[4,5-b]pyridine is also reported.     

Synthesis of New Furo[2,3-b]pyridine and Furo[3,2-d]pyrimidine Derivatives

Russian Journal of Organic Chemistry - New furo[2,3-b]pyridine and pyrido[3′,2′:4,5]furo[3,2-d]pyrimidine derivatives were synthesized from ethyl...     

Cyclization of substituted 3,4-diaminopyridines into 1H-[1,2,3]triazolo[4,5-c]pyridine 2-oxide derivatives during the nitration process

The nitration of pyridine-3,4-diamine, its N,N′-diacetyl derivative, and N ⁴-alkylpyridine-3,4-diamines with excess nitric acid in concentrated sulfuric acid at 60°C was accompanied by cyclization with formation of the corresponding 1-substituted 4-nitro-1H-[1,2,3]triazolo[4,5-c]pyridine 2-oxides. 4-Chloro-1H-[1,2,3]triazolo[4,5-c]pyridine 2-oxide derivatives were obtained under analogous conditions from 2-chloropyridine-3,4-diamine, its N,N′-diacetyl derivative, and 2-chloro-N ⁴-methylpyridine-3,4-diamine. The nitration of these compounds at 80–90°C gave 4-chloro-7-nitro-1H-[1,2,3]triazolo[4,5-c]pyridine 2-oxides.     

Studies on the chemical synthesis of potential antimetabolites. 30. Regioselective introduction of a chlorine atom into the imidazo[4,5-b]pyridine nucleus

Reactions of some imidazo[4,5-b]pyridine 4-oxides with phosphoryl chloride are described. Treatment of N-1-substituted imidazo[4,5-b]pyridine 4-oxides with phosphoryl chloride led to the predominant formation of 7-chloro derivatives. This feature was successfully applied to the preparation of a chloroimidazo[4,5-b]pyridine nucleoside, which served as an important precursor of 1-deazaadenosine.     

Reaction of 3H-oxazolo[4,5-b]pyridine-2-thione with amines

Primary amines and diethylamine react with oxazolo[4,5-b]pyridine thione to form N-(3-hydroxy-2-pyridyl)thioureas whereas cyclic secondary amines and aniline form 2-aminooxazolo[4,5-b]pyridines. Exchange of the benzene ring in benzoxazolinethione for pyridine causes the properties of the resultant oxazolopyridine-2-thione to resemble those of 5- and 6-nitrobenzoxazolinethiones.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1129–1130, August, 1987.     

Selective C-acylation of 2-aminoimidazo[1,2-a]pyridine: application to the synthesis of imidazopyridine-fused [1,3]diazepinones

A series of 20 optically pure 3,4-dihydro-5H-pyrido[1',2':1,2]imidazo[4,5-d][1,3]diazepin-5-ones which form a new family of azaheterocycle-fused [1,3]diazepines were synthesized in four steps with 17-66% overall yields. The key step consists of a selective C-acylation reaction of easily accessible 2-aminoimidazo[1,2-a]pyridine at C-3.     

Reactions with 3,6‐diaminothieno[2,3‐b]‐pyridines: Synthesis and characterization of several new fused pyridine heterocycles

6‐Aminopyridine‐2(1H)thiones 1 reacting with α‐halo‐compounds 2a–c afforded the alkylthiopyridine derivatives 3a–c which in turn cyclized to the corresponding thieno[2,3‐b]pyridine derivatives 4a–c . Several thieno[2,3‐b]pyridine derivatives 7, 16, 19 , pyrido[3′,2′:4,5]thieno[3,2‐d]pyrimidine derivatives 6a,b, 11a–c, 21 and pyrido[3′,2′:4,5]thieno[3,2‐c]pyridazine derivatives 13, 17 were prepared starting from compounds 4a–c . © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:405–413, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20313     

Synthesis of Some New Imidazo[4,5-B]Pyridine Derivatives Using 2-Cyanomethyl-1-Methyl-1H-Imidazo[4,5-B]Pyridine

Abstract

The reactions of 2-cyanomethyl-1-methyl-1H-imidazo[4,5-b]pyridine with isothiocyanates, nitroso compounds, acid chlorides, and thioglycolic acid were investigated. New imidazo[4,5-b]pyridine derivatives with various substituents in 2-position and derivatives of the new pyrrolo[2′,1′:2,3]imidazo[4,5-b]pyridine ring system were synthesized. The compounds obtained were tested in vitro for their tuberculostatic activity.     

An unexpected [2+2]-cycloaddition reaction of 4-methyldithieno-[3,4-b:3′,2′-d]pyridinium iodide with dimethyl acetylenedicarboxylate

An unexpected [2+2]-cycloaddition occured in the reaction of 4-methyldithieno-[3,4-6:3′,2′-d]pyridinium iodide (3)with two equivalents of DMAD, giving 4-(trans-1,2-dicarbomethoxy-2- iodovinyl)-5-methyl-6,7-dicarbomethoxy-4,5-dihydrothieno [23-c]quinoline (4) in 54% yield. 4 is formed via 4-methyl-5-(trans-1,2-dicarbomethoxy-2-iodo-4,5-dihydrothieno [3,4-b:3′,2′-d]pyridine (16), followed by [2+2]-cycloaddition. The primary adduct rearranges via a thiepin to an episulfide which eliminates sulfur to give 4.