Selective Synthesis of Bis-Heterocycles via Mono- and Di-Selenylation of Pyrazoles and Other Heteroarenes

Kour, Jaspreet; Khajuria, Pratiksha; Verma, Praveen Kumar; Kapoor, Neharika; Kumar, Amit; Sawant, Sanghapal D.

doi:10.1021/acsomega.2c00323

Cited by 19 publications

(7 citation statements)

References 58 publications

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“…The reaction proceeds with keto-enol tautomerization of ketone, followed by nucleophilic attack of enol form on selenium dioxide gave the intermediate dialkyl selenide (35A). Subsequently, the nucleophilic attack of phenol on dialkyl selenide gave the desired α-arylselanyl ketone product (35). The mechanism is further confirmed by the isolation and characterization of dialkyl selenide (Scheme 12).…”

Section: Selenation and Selenocyanation Reactionsmentioning

confidence: 73%

“…[31] They have reported a novel p-toluene sulphonic acid (p-TSA) mediated synthesis of α-arylselanyl ketones (33) by three component reaction. The reaction of selenium dioxide carried out with alkyl aryl ketones/ alkyl alkyl ketones (33) and electron rich phenols (34) in the presence of p-TSA at 60 °C gave the desired α-arylselanyl ketones (35). Using this methodology, successfully twenty three substrates have been synthesized with good to excellent yield.…”

Section: Selenation and Selenocyanation Reactionsmentioning

confidence: 99%

“…After that, the reaction of phenylglyoxal ( 45 Kour and co-workers have reported selenylation of pyrazoles (47) using selenium dioxide as a selenylating reagent. [35] In this methodology, mono-selenylation of pyrazoles (dipyrazolyl selenide) (48) carried out by treating pyrazoles (1 equiv.) with selenium dioxide (2 equiv.)…”

Section: Selenation and Selenocyanation Reactionsmentioning

confidence: 99%

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Selenium dioxide as a selenylating reagent: An overview and its Sanguine future

Saroha,

Swami,

Singh

et al. 2023

ChemistrySelect

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Selenylation of heterocyclic and carbocyclic compounds using selenium dioxide as a selenylating reagent has emerged as a novel research area. Selenium dioxide is a cheap, easily available and odorless selenium source with wide functional group tolerance. Selenium dioxide is much known for α‐oxidation reactions but this review will elaborate its role as oxidizing as well as selenylating agents. In this review, we have summarized the selenylation of different molecules like anilines, phenylhydrazines, aryl alkyl ketones, phenols, indoles, active methylene compounds, imidazole heterocycles, 1,3‐diones, boronic acids, pyrazoles, 2‐hydroxy acetophenones, alkyl halides and different electron rich arenes along with detailed mechanism. Triselenium dicyanide is a yellow colored addition product that has now been emerged as a well‐known reagent of selenocyanation and many research groups extensively working on it. Selenium containing compounds possess biological as well as pharmacological activity. The immense potential of selenium dioxide as a selenylating reagent attracted the interest of researchers working on selenylation.

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Section: Selenation and Selenocyanation Reactionsmentioning

confidence: 73%

Section: Selenation and Selenocyanation Reactionsmentioning

confidence: 99%

Section: Selenation and Selenocyanation Reactionsmentioning

confidence: 99%

See 1 more Smart Citation

Selenium dioxide as a selenylating reagent: An overview and its Sanguine future

Saroha,

Swami,

Singh

et al. 2023

ChemistrySelect

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“…omatic systems. Recently, notable progress has been made in the use of aromatic electrophilic substitution to synthesize arylselenium compounds [26][27][28]. Noteworthy examples are the use of SeO 2 as selenium source in aromatic electrophilic substitution reactions [27][28][29].…”

Section: Introductionmentioning

confidence: 99%

“…Recently, notable progress has been made in the use of aromatic electrophilic substitution to synthesize arylselenium compounds [26][27][28]. Noteworthy examples are the use of SeO 2 as selenium source in aromatic electrophilic substitution reactions [27][28][29]. Selenium dioxide is a well-known oxidizing agent for the allylic oxidation and oxidation of α-CH bonds located adjacent to electron-withdrawing groups [30][31][32].…”

Section: Introductionmentioning

confidence: 99%

Competing electrophilic substitution and oxidative polymerization of arylamines with selenium dioxide

Selladurai,

Karuthapandi

2024

Beilstein J. Org. Chem.

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This article describes the detailed analysis of the reaction between arylamines, such as aniline, o-anisidine, and methyl anthranilate, with selenium dioxide in acetonitrile. A systematic analysis of the reaction products with the help of 77Se NMR and single-crystal X-ray crystallography revealed that the reaction progress follows three major reaction pathways, electrophilic selenation, oxidative polymerization, and solvent oxidation. For aniline and o-anisidine, predominant oxidative polymerization occurred, leading to the formation of the respective polyaniline polymers as major products. For methyl anthranilate, the oxidative polymerization was suppressed due to the delocalization of amine lone pair electrons over the adjacent carboxylate function, which prompted the selenation pathway, leading to the formation of two of the isomeric diorganyl selenides of methyl anthranilate. The diaryl selenides were structurally characterized using single-crystal X-ray diffraction. Density functional theory calculations suggest that the highest occupied molecular orbital of methyl anthranilate was deeply buried, which suppressed the oxidative polymerization pathway. Due to solvent oxidation, oxamide formation was also noticed to a considerable extent. This study provides that utmost care must be exercised while using SeO2 as an electrophile source in aromatic electrophilic substitution reactions.

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TBAX/Oxone‐Mediated Halogenation of Pyrazoles and Other Heterocycles: An Entry to Important Cross‐Coupling Reactions

Kour

Khajuria

Sharma

et al. 2022

Chemistry An Asian Journal

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A facile, sustainable and eco-friendly protocol has been developed for the halogenation of various heterocycles using TBAX (TBAI/TBAB/TBACl) as halogenating agent, which afforded the products in 90-95% isolated yields. The reaction proceeds with low-cost TBAX and uses greener conditions like EtOH as a solvent and microwave as an alternative energy source for reaction. This protocol has been applied on pyrazoles and extended to different heterocycles like 7-azaindole, indazole, indole and 2-phenylimidazo[1,2α]pyridines. The gram-scale iodination reaction has also been successfully performed by optimizing conventional heating conditions, which demonstrates its potential applicability in organic synthesis. Further these halogenated pyrazoles have been utilized for different coupling reactions including formation of arylated, alkynylated and sulfenated pyrazoles. However, TBAF mediated fluorination did not work.

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Selective Synthesis of Bis-Heterocycles via Mono- and Di-Selenylation of Pyrazoles and Other Heteroarenes

Cited by 19 publications

References 58 publications

Selenium dioxide as a selenylating reagent: An overview and its Sanguine future

Selenium dioxide as a selenylating reagent: An overview and its Sanguine future

Competing electrophilic substitution and oxidative polymerization of arylamines with selenium dioxide

TBAX/Oxone‐Mediated Halogenation of Pyrazoles and Other Heterocycles: An Entry to Important Cross‐Coupling Reactions

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