The Thermal Decomposition of 2-Azidobenzylideneamines

Krbechek, L. O.; Takimoto, H. H.

doi:10.1021/jo01028a037

Cited by 39 publications

(10 citation statements)

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“…The required anilides 245 can be prepared in high In some cases, compounds 248 are converted into 2H-indazoles 250 even in the process of the azide formation [228]. The thermal decomposition of other 2-azidobenzylideneamine derivatives into 2-substituted-2H-indazoles is also described [229].…”

Section: Formation Of One N-n Bondmentioning

confidence: 99%

Five‐Membered Heterocycles: 1,2‐Azoles. Part 1. Pyrazoles

Elguero

Silva

Tomé

2011

Modern Heterocyclic Chemistry

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Section: Formation Of One N-n Bondmentioning

confidence: 99%

Five‐Membered Heterocycles: 1,2‐Azoles. Part 1. Pyrazoles

Elguero

Silva

Tomé

2011

Modern Heterocyclic Chemistry

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“…It is important to underline that at present a wide range of precursors has been used to synthesize the 2H-indazole ring, in practice including all strategic routes for its synthesis. For example, 2H-indazoles have been synthesized from 2-azidobenzylideneamines [17] or 2-azidobenzoylamines [18,19], oxidative cyclization from N-acylhydrazones of 2-aminoacylbenzenes [20,21], reaction of carbenes with azobenzene [22,23], rearrangement of ortho-substituted azobenzenes [24,25], and reductive heterocyclization of ortho-nitrobenzylideneamines [26][27][28], and heterocyclization of ortho-nitrobenzylamines [29][30][31][32][33]. A variant of the formation of the 2H-indazole system from compounds containing the pyrazole unit have been described.…”

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A new effective route for the synthesis of substituted 2h-indazoles

Mochalov

Khasanov

Трофимова

et al. 2009

Chem Heterocycl Comp

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A two-stage synthesis of 2H-indazoles has been established, based on consecutive reactions of reduction of 2-alkyl-, 2-cyclopropyl-, and 2-arylcarbonylazobenzenes to phenylazo-substituted benzyl alcohols and intramolecular heterocyclization of the reduction products under the influence of organic acids.In recent years there has been a considerably strengthened interest in the synthesis and study of the medicobiological properties of derivatives of 2H-indazoles, resulting from the observation in a series of compounds which are seldom encountered in nature, a class of heterocycles with a wide range of biological activity: antiangiogenic [1], anticarcinogenic and anti-inflammatory [2,3], antimicrobial [4], antifungal [5,6], cytotoxic [7], and antihelminthic [8]. In addition compounds of this class show potential as inhibitors of NO-synthetases [9, 10], protein kinases [11,12], tubulin [13], modulators of X-receptors of the liver [14], and they also show properties of male contraceptives [15,16].The discovery of the biological activity of the 2H-indazoles caused the real problem of the synthesis of new derivatives of this class of heterocycles. It is important to underline that at present a wide range of precursors has been used to synthesize the 2H-indazole ring, in practice including all strategic routes for its synthesis. For example, 2H-indazoles have been synthesized from 2-azidobenzylideneamines [17] or 2-azidobenzoylamines [18,19], oxidative cyclization from N-acylhydrazones of 2-aminoacylbenzenes [20,21], reaction of carbenes with azobenzene [22,23], rearrangement of ortho-substituted azobenzenes [24,25], and reductive heterocyclization of ortho-nitrobenzylideneamines [26][27][28], and heterocyclization of ortho-nitrobenzylamines [29][30][31][32][33]. A variant of the formation of the 2H-indazole system from compounds containing the pyrazole unit have been described. For example, oxidation of 4,5-tetramethylenepyrazoles with dichlorodicyanobenzoquinone gave substituted 2H-indazoles in high yield [34]. However, despite the abundance of variants for the construction of the 2H-indazole ring, the variation of substituents is practically limited to those in positions 2 and 3, and only in the papers [30,31,33] were syntheses of 2H-indazoles containing substituents in the annelated benzene ring reported.

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“…According to [17], 2-substituted indazoles were isolated in high yield from the thermolysis of o-azidobenzylidene amines. From this it seemed expedient to use the thermolysis of the azido imines 5a-f for the pyrazoloannelation of the pyridine ring.…”

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Synthesis of 6-aryl-1,6-dihydro-dipyrazolo[3,4-b:4,3-c]pyridines

Вовк¹,

Мельніченко²,

Sukach

et al. 2004

Chem Heterocycl Compd

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Keywords: N-aryl-6-azido-1H-pyrazolo [3,4-b]pyridine-5-carbaldimines, 6-aryl-1,6-dihydrodipyrazolo- [3,4-b:4,3-e]pyridines, thermolysis.Dipyrazolo [3,4-b:4,3-e]pyridines are examples of condensed heterocyclic compounds with notable pharmacological activity, for example bactericidal [1], sedative [2], and antiasthmathic [3]. Substances with electroluminescent properties are also found among them [4,5]. Only 1,7-disubstituted dipyrazolo[3,4-b:4,3-e]-pyridines can be synthesized by the reported cyclization of 2,6-dichloro-3,5-diformylpyridine with hydrazines [6], 5-aminopyrazoles with carbonyl compounds [7-10], and pyrazolin-5-ones with aldehydes and arylimines [11]. The intramolecular cyclocondensation of the hydrazone of 6-chloropyrazolo[3,4-b]pyridine-5-carbaldehyde was used to prepare 3-methyl-1-phenyl-1,7-dihydrodipyrazolo[3,4-b:4,3-e]pyridine [12]. N N N C H Cl Me Ph NNH 2 N N N N H N Me Ph EtOH, ∆, 18 hThere are no reports of 1,6-dihydro analogs of these heterocyclic systems in the literature. It is for this reason that we examine preparatively suitable routes to their synthesis in this paper.6-Chloro-3-methyl-1-phenyl-1H-pyrazolo[3,4-b]pyridine-5-carbaldehyde (1), synthesized from 5-acetylamino-3-methyl-1-phenylpyrazole by the Vilsmeier-Haack method [12] was proposed as the starting material for the synthesis of the desired materials. Compound 1, like 5-chloropyrazole-4-carbaldehyde [13][14][15], was converted in 85% yield to 6-azidopyrazolo[3,4-b]pyridine-5-carbaldehyde 2 by reaction with NaN 3 in DMSO in the presence of the phase transfer catalyst Bu 4 N + I -.An investigation of the thermal properties of compound 2 showed that, in contrast to its close analog, 2-azido-7-methylquinoline-3-carbaldehyde, which is converted into the corresponding tetrazoloquinoline even at 40°C, it is quite stable and only underwent cyclization to pyrazolo[3,4-e][1,2,3,4]tetrazolo[1,5-a]pyridine 3 on refluxing in toluene for 6 h. It was therefore suggested that when the condensation of the azidoaldehyde 2 with

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The Thermal Decomposition of 2-Azidobenzylideneamines

Cited by 39 publications

References 1 publication

Five‐Membered Heterocycles: 1,2‐Azoles. Part 1. Pyrazoles

Five‐Membered Heterocycles: 1,2‐Azoles. Part 1. Pyrazoles

A new effective route for the synthesis of substituted 2h-indazoles

Synthesis of 6-aryl-1,6-dihydro-dipyrazolo[3,4-b:4,3-c]pyridines

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