Synthesis of fused pyrazoles via intramolecular cyclization of appropriately ortho-substituted nitroarenes and nitroheteroarenes

Remennikov, G. Ya.

doi:10.1007/s10593-017-2028-6

Cited by 13 publications

(2 citation statements)

References 75 publications

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“…These popular moieties are heavily used for the manufacture of agrochemicals, dyes, pharmaceuticals, high explosives, plastics, pesticides, feedstocks etc and ubiquitous commodity of organic molecules [2] . Most importantly, the nitro group on the aromatic ring has been transformed into a wide array of functionalities [3] such as amine, azide, amide, hydroxylamine, sulfonamide, azo, nitrile, alkyl, alkenyl, alkynyl, halides etc and various complex heterocycles [4] . In addition, they can inherently participate S N Ar reactions with a variety of nucleophiles, leading to various functionalized arenes [5] .…”

Section: Methodsmentioning

confidence: 99%

“…[2] Most importantly, the nitro group on the aromatic ring has been transformed into a wide array of functionalities [3] such as amine, azide, amide, hydroxylamine, sulfonamide, azo, nitrile, alkyl, alkenyl, alkynyl, halides etc and various complex heterocycles. [4] In addition, they can inherently participate S N Ar reactions with a variety of nucleophiles, leading to various functionalized arenes. [5] Keeping in view of the rich applications, they were traditionally synthesized via an aromatic electrophilic nitration of arenes using a mixture of excess fuming HNO 3 and H 2 SO 4 (Scheme 1a).…”

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confidence: 99%

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Reversal Reactivity of β‐Alkylnitroalkenes as 1,3‐Binucleophiles: Application to Nitroarenes using Organocatalysis

et al. 2021

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An efficient pyrrolidine : 4-ClBzOH salt (catalyst IV) catalyzed [3 + 3] cyclization reaction of β-alkyl-substituted nitroalkenes as 1,3-binucleophiles with various β-aryl/alkyl/ alkenyl-substituted acroleins in an open-atmosphere is reported. Eventually, this tunable organocatalytic reaction creates one CÀ C and C=C bonds selectively that turns out to have a wide substrate scope, which affords a series of substituted nitroarenes in good to high yields. In addition, several other positive features are associated with this organocatalytic approach such as evading toxic metalcatalysts, no need for external oxidant and nitrating agent, 100% carbon-economical, excellent tolerance of functionalities, water as a sole by-product, circumventing of prefunctionalized arenes etc. Moreover, a range of important hetero-and carbocycles such as 2-arylcarbazole, 2,6-diphenylindole, 2'-chloro-1,1' : 4',1''-terphenyl and 1 : 1' : 4',1''-terphenyl were accessed from nitroarenes through our unique methods.

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Section: Methodsmentioning

confidence: 99%

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confidence: 99%

Reversal Reactivity of β‐Alkylnitroalkenes as 1,3‐Binucleophiles: Application to Nitroarenes using Organocatalysis

et al. 2021

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A novel synthetic approach to Pyrazolooxazines. One‐pot synthesis of Pyrazolo[5,1‐c][1,4]oxazine derivatives from 2,2‐dichlorovinylacetophenones

Guirado

Martiz

Vera

et al. 2022

Journal of Heterocyclic Chem

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New synthetic approach to pyrazolo[1,5‐a]pyrazine derivatives from 2,2‐dichlorovinylacetophenones

Guirado,

Vera,

Martiz

et al. 2023

Journal of Heterocyclic Chem

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New efficient synthetic methods in pyrazoline and pyrazolopyrazine chemistry have been developed starting from 2,2‐dichlorovinylacetophenones 1, which were sequentially transformed into 3‐aryl‐5‐dichloromethyl‐1‐(2‐hydroxiethyl)‐2‐pyrazolines 2, 3‐aryl‐5‐dichloromethyl‐1‐(2‐O‐tosylhydroxyethyl)‐2‐pyrazolines 3, 3‐aryl‐5‐dichloromethyl‐1‐(2‐azidoethyl)‐2‐pyrazolines 4, and 3‐aryl‐5‐dichloromethyl‐1‐(2‐aminoethyl)‐2‐pyrazoline hydrochlorides 5, by reaction with 2‐hydroxyethylhydrazine, O‐tosylation, azidation, and catalytic hydrogenation, respectively. Compounds 5 were treated with aqueous sodium hydroxide to provide 2‐aryl‐4,5,6,7‐tetrahydropyrazolo[1,5‐a]pyrazines 6 in one‐step conversions involving cyclization and aromatization. A reaction mechanism has been proposed with the aid of DFT theoretical calculations. Compounds 6 could also be obtained directly in one‐pot reactions of tosylates 3 with ammonium hydroxide followed by the addition of sodium hydroxide. The molecular structure of 2‐(4‐chlorophenyl)‐4,5,6,7‐tetrahydropyrazolo[1,5‐a]pyrazine 6c was determined by X‐ray crystallography. Simplicity, good overall yields and inexpensive starting materials are advantageous features of the improved synthetic procedures reported herein.

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Synthesis of fused pyrazoles via intramolecular cyclization of appropriately ortho-substituted nitroarenes and nitroheteroarenes

Cited by 13 publications

References 75 publications

Reversal Reactivity of β‐Alkylnitroalkenes as 1,3‐Binucleophiles: Application to Nitroarenes using Organocatalysis

Reversal Reactivity of β‐Alkylnitroalkenes as 1,3‐Binucleophiles: Application to Nitroarenes using Organocatalysis

A novel synthetic approach to Pyrazolooxazines. One‐pot synthesis of Pyrazolo[5,1‐c][1,4]oxazine derivatives from 2,2‐dichlorovinylacetophenones

New synthetic approach to pyrazolo[1,5‐a]pyrazine derivatives from 2,2‐dichlorovinylacetophenones

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