Competitive cyclisations of singlet and triplet nitrenes. Part 8. The 1-(2-nitrenophenyl)pyrazoles and related systems

Lindley, John M.; McRobbie, Ian; Meth‐Cohn, Otto; Suschitzky, H.

doi:10.1039/p19800000982

Cited by 33 publications

(10 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…up to pH 2-3. The suspension was stirred and added of a solution of 2-nitro-5-chlorophenylhydrazine 46 (1.0 mmol) in ethanol (20 mL); the reaction was stirred at refluxing temperature, for 2 h, and monitored by TLC until starting material disappearing. The formed sodium chloride was filtered off and the ethanol solution was evaporated in vacuo.…”

Section: -(2-nitro-5-chlorophenyl)-2h-4-methyl-5-iminopyrazole (1)mentioning

confidence: 99%

“…up to pH 2-3. The suspension was stirred and added of a solution of 2-nitro-5-chlorophenylhydrazine 46 (1.0 mmol) in ethanol (20 mL); the reaction was stirred at refluxing temperature, for 10 h, and the imino derivative (1) was converted in the corresponding 5-aminopyrazole 2. By TLC monitoring is possible to evidence the spot of 5-aminopyrazole (2) at lower R f than 5iminopyrazole (1); when the reaction was finished the ethanol solution was evaporated and the final precipitate recrystallized with ethanol (1.05 g, 42% yield).…”

Section: -(2-nitro-5-chlorophenyl)-2h-4-methyl-5-iminopyrazole (1)mentioning

confidence: 99%

See 1 more Smart Citation

Development of ligands at γ-aminobutyrric acid type A (GABAA) receptor subtype as new agents for pain relief

Guerrini

Ciciani

Bruni

et al. 2011

Bioorganic & Medicinal Chemistry

View full text Add to dashboard Cite

The identification of compounds with selective anxiolytic-like effects, exerted through the benzodiazepine site on γ-aminobutyric acid type A (GABA(A)) receptors, and that show pronounced antihyperalgesia in several pain models, has oriented research towards the development of new agents for the relief of pain. Starting from our previously reported ligands at the benzodiazepine site on GABA(A) receptors showing selective anxiolytic-like effects, we have designed new compounds with the aim of identifying those devoid of the typical side effects of the classical benzodiazepines. Our preliminary results indicate that compounds 4, 10(±) and 11 have a very promising antihyperalgesic profile in different animal pain models (peripheral mono-neuropathy, STZ-induced hyperalgesia). In particular 11 exhibits high potency since it exerted its protective effect starting from the dose of 3mg/kg po, after single injection.

show abstract

“…up to pH 2-3. The suspension was stirred and added of a solution of 2-nitro-5-chlorophenylhydrazine 46 (1.0 mmol) in ethanol (20 mL); the reaction was stirred at refluxing temperature, for 2 h, and monitored by TLC until starting material disappearing. The formed sodium chloride was filtered off and the ethanol solution was evaporated in vacuo.…”

Section: -(2-nitro-5-chlorophenyl)-2h-4-methyl-5-iminopyrazole (1)mentioning

confidence: 99%

“…up to pH 2-3. The suspension was stirred and added of a solution of 2-nitro-5-chlorophenylhydrazine 46 (1.0 mmol) in ethanol (20 mL); the reaction was stirred at refluxing temperature, for 10 h, and the imino derivative (1) was converted in the corresponding 5-aminopyrazole 2. By TLC monitoring is possible to evidence the spot of 5-aminopyrazole (2) at lower R f than 5iminopyrazole (1); when the reaction was finished the ethanol solution was evaporated and the final precipitate recrystallized with ethanol (1.05 g, 42% yield).…”

Section: -(2-nitro-5-chlorophenyl)-2h-4-methyl-5-iminopyrazole (1)mentioning

confidence: 99%

Development of ligands at γ-aminobutyrric acid type A (GABAA) receptor subtype as new agents for pain relief

Guerrini

Ciciani

Bruni

et al. 2011

Bioorganic & Medicinal Chemistry

View full text Add to dashboard Cite

show abstract

“…The characteristics of the pyrazolol 4c were fully in agreement with those for the 1-(2,4-dinitrophenyl)-3-methyl-1H-pyrazol-5-ol obtained before by an alternative method [10].…”

mentioning

confidence: 60%

Synthesis of 1-aryl(hetaryl)pyrazol-5-ols and azopyrazoles on their basis

Kuznetsov

Ruchkina

Кобраков

2011

Chem Heterocycl Comp

View full text Add to dashboard Cite

Treatment of 3,5-dichloropyrid-2-ylhydrazine, and of mono-and dinitrophenylhydrazines with acetoacetic ester gave hydrazones and the products of their cyclization, namely pyrazolols. It was shown that acetoacetic ester 2,4-dinitrophenylhydrazone cyclizes to the pyrazolol only by using PPA while other studied hydrazones undergo tarring under these conditions. The products of azocoupling of pyrazolols with 3-diazonio-4-hydroxy-5-nitrobenzenesulfonate or 2-hydroxy-5-nitrophenyldiazonium salts are able to color textile materials. The fungicidal activity of the synthesized compounds has been studied.Our analysis of literature sources based on CAS data and available through STN has shown that the interest in the synthesis and studies of the properties of pyrazole derivatives has persisted at a constantly high level while, in the last 20 years, there has occurred an increasing trend in the number of publications and a jump has been noted in the number of patents to 30-35 per year [1, 2]. This is explained by the fact that, amongst pyrazole derivatives, there are known chemical agents for plant protection, chemico-pharmaceutical preparations, antioxidants, reagents for chemical analysis and for organic synthesis, dyes, and pigments.In our work we have synthesized a series of pyrazol-5-ol derivatives containing a substituent in the 1 position which can undergo further chemical transformation, and of derived azopyrazoles.One of the most convenient and widely used methods for preparing pyrazol-5-ols is the heterocyclization of substituted hydrazines with acetoacetic ester [3] and it is known that the process can occur both with and without the separation of the intermediate hydrazones 3. R NHNH 2 Me O O OEt Me N O N H OEt R N N Me O H R + 1a-e 2 3a-e 4a-e -EtOH -H 2 O1,3,4 а R = Ph, b R = 4-nitrophenyl, c R = 2,4-dinitrophenyl, d R = 2-methoxy-5-nitrophenyl, e R = 3,5-dichloropyrid-2-yl

show abstract

“…

…”

mentioning

confidence: 98%

Synthesis of 4-substituted imidazo[1,2-a]quinoxalines

Lamberth¹

1999

J. prakt. Chem.

View full text Add to dashboard Cite

[6,7] and triazolo [4,3-a]quinoxalines [8,9] have been described, which enable the selective and diverse substitution of the 4-position, this is not the fact for imidazo[1,2-a]quinoxalines. Known procedures for the preparation of imidazo[1,2-a]quinoxalines either start from 2-chloroquinoxalines [10,11], in which a future 4-substituent would have to be installed already in the starting material, or use the intramolecular condensation of 2-methyl or 2-formyl substituted 1-(2-aminophenyl)imidazoles [12,13] with no possibility for the introduction of a 4-function. Only one example in the patent literature describes an appropriate approach to 4-substituted imidazo[1,2-a]quinoxalines, based on the intramolecular ring closure between an acylamino function and the 2-position of an 1-arylsubstituted imidazole [14]. Unfortunately, the application of this method was limited so far, because many products are formed in extraordinary low yields. Herein we present an improved procedure, by which the amount of phosphorus oxychloride in the key step could be reduced dramatically, resulting in increased yields of the products.The synthesis starts with the known copper oxide catalyzed arylation of imidazole with 1-fluoro-2-nitrobenzene (3). The PROCEDURES/DATA _________________________________________________________________ 492

show abstract

Competitive cyclisations of singlet and triplet nitrenes. Part 8. The 1-(2-nitrenophenyl)pyrazoles and related systems

Cited by 33 publications

References 7 publications

Development of ligands at γ-aminobutyrric acid type A (GABAA) receptor subtype as new agents for pain relief

Development of ligands at γ-aminobutyrric acid type A (GABAA) receptor subtype as new agents for pain relief

Synthesis of 1-aryl(hetaryl)pyrazol-5-ols and azopyrazoles on their basis

Synthesis of 4-substituted imidazo[1,2-a]quinoxalines

Contact Info

Product

Resources

About