Spirodiazaselenuranes: synthesis, structure and antioxidant activity

Lamani, Devappa S.; Bhowmick, Debasish; Mugesh, Govindasamy

doi:10.1039/c2ob26156a

Cited by 35 publications

(23 citation statements)

References 67 publications

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“…It is shown earlier that the cyclization process is very rapid at room temperature (25 °C) in the presence of aromatic substituents on the nitrogen atoms. Therefore, all the reactions were carried out at lower temperature (−25 °C) to isolate the intermediates involved in the process [21,22]. In the present study, it is observed that the diaryl selenides 15-21 react with H2O2 or ONOO − to produce the corresponding selenoxides 22-28, which could be isolated and characterized at room temperature.…”

Section: Mechanism Of Cyclizationmentioning

confidence: 87%

“…Similarly, our previous study also showed that some of the spirodiazaselenuranes containing electron donating substituents on the aromatic rings exhibit moderate catalytic activities for the reduction of peroxides [22]. Therefore, the GPx-like catalytic activities of all the selenides 15-21 and the spirodiazaselenuranes 29-35 were studied using H2O2 as the substrate and glutathione (GSH) as the co-substrate to understand the effect of different benzylic, heterocyclic and aliphatic substituents on the antioxidant activity.…”

Section: Glutathione Peroxidase (Gpx)-like Activitymentioning

confidence: 99%

“…2,2′-Selenodibenzoyl chloride, which is the key precursor for the selenides used in this study, was synthesized by the reaction of disodium diselenide and 2-iodobenzoic acid in the presence of copper powder with some slight modifications of the reported procedure [22,24], followed by the reaction with thionyl chloride. Treatment of diaryl selenenyl chloride with various substituted amines produce the selenides 15-21 (Scheme 1), which are oxidized to the corresponding selenoxide intermediates 22-28 in the presence of H2O2 or t-BuOOH.…”

Section: Synthesis Of Spirodiazaselenuranesmentioning

confidence: 99%

“…It is proposed that the phenyl substituent on the nitrogen atom is important, as it facilitates the formation of the diazaselenuranes by increasing the stability of the Se-N bonds. Furthermore, our previous study by substituting the hydrogen atom on the phenyl group with different electron donating and electron withdrawing atoms or groups showed that the electron donating substituents generally enhance the stability of the Se-N bonds and their antioxidant activity [22]. Very recently, Singh and co-workers have synthesized and characterized a new pincer type bicyclic diazaselenurane 14 in which the two amide groups are present in the same phenyl ring forming the bicycles [23].…”

Section: Introductionmentioning

confidence: 99%

“…Very recently, Singh and co-workers have synthesized and characterized a new pincer type bicyclic diazaselenurane 14 in which the two amide groups are present in the same phenyl ring forming the bicycles [23]. Earlier reports show that oxidation of selenides by H2O2 produces the corresponding selenoxides, which undergo a rapid cyclization via a hydroxyselenurane intermediate to produce the spirodiazaselenuranes [21,22]. The aromatic ring on the nitrogen plays an important role in the cyclization by stabilizing the Se-N bonds in the spirodiazaselenurane.…”

Section: Introductionmentioning

confidence: 99%

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Substituent Effects on the Stability and Antioxidant Activity of Spirodiazaselenuranes

2015

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Spirodiazaselenuranes are structurally interesting compounds and the stability of these compounds depends highly on the nature of the substituents attached to the nitrogen atoms. Aromatic substituents are known to play important roles in stabilizing the Se-N bonds in spiro compounds. In this study, several spirodiazaselenuranes are synthesized by introducing benzylic and aliphatic substituents to understand their effect on the stability of the Se-N bonds and the antioxidant activity. Replacement of phenyl substituent by benzyl/alkyl groups significantly reduces the stability of the spirodiazaselenuranes and slows down the oxidative cyclization process. The selenium centre in the spiro compounds undergoes further oxidation to produce the corresponding selenurane oxides, which are stable at room temperature. Comparison of the glutathione peroxidase (GPx) mimetic activity of the compounds showed that the diaryl selenides having heterocyclic rings are significantly more active due to the facile oxidation of the selenium centre. However, the activity is reduced significantly for compounds having aliphatic substituents. In addition to GPx activity, the compounds also inhibit peroxynitrite-mediated nitration and oxidation reaction of protein and small molecules, respectively. The experimental observations suggest that the antioxidant activity is increased considerably upon substitution of the aromatic group with the benzylic/aliphatic substituents on the nitrogen atoms.

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Section: Mechanism Of Cyclizationmentioning

confidence: 87%

Section: Glutathione Peroxidase (Gpx)-like Activitymentioning

confidence: 99%

Section: Synthesis Of Spirodiazaselenuranesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Substituent Effects on the Stability and Antioxidant Activity of Spirodiazaselenuranes

2015

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Enzyme Mimetic Chemistry of Organoselenium Compounds

Bhowmick

Mugesh

2013

Patai's Chemistry of Functional Groups

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Selenium plays a key role in biology by mediating many important physiological processes. In proteins, selenium is present in the form of selenocysteine (Sec, U), which is generally considered as the 21st amino acid. Although Sec is a homolog of cysteine (Cys, C) and has similar structural and functional properties, the reactivity of Sec residues in proteins is significantly different from that of Cys due to the low redox potential and high nucleophilicity of Sec. In this chapter, some of the well‐studied examples of selenoenzymes and their synthetic mimics are discussed. Synthetic compounds that mimic the function of glutathione peroxidase (GPx) and iodothyronine deiodinase (ID) are used extensively to understand the chemical mechanism of the enzymes. The chemistry of Sec residue at the active site of GPx is widely studied with the help of a number of small‐molecule organoselenium compounds. Ebselen was the first synthetic GPx mimic to undergo clinical studies for a number of disease states, including stroke, inflammation, and hearing loss, although ebselen and its analogues exhibit poor GPx activity in the presence of thiols due to undesired thiol‐exchange reactions. The GPx activity of several tert ‐amine‐based diselenides is found to be much higher than that of ebselen and related compounds. In these compounds, the amine moiety plays an important role in modulating the reactivity of different intermediates involved in the catalytic cycle. In addition to selenenyl amides and diaryl diselenides, a number of spirodiazaselerunanes are studied as GPx mimics. The role of Sec in iodothyronine deiodinases, which control the thyroid hormone levels, is also discussed in this chapter. Recently, some naphthyl‐based selenols and thiols are reported as mimics of deiodinases.

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Contrasting Reactivity of 2‐chloro‐1‐formyl‐3‐hydroxymethylenecyclohexene and its Schiff Bases towards Disodium Diselenide: Isolation of Selenospirocycles versus Azapentalenes

et al. 2018

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A convenient approach for the synthesis of alicyclic selenospirocycles, 24 and 25, stabilized by intramolecular chalcogen bonding (IChB) is reported by the reaction of 5alkyl-2-chloro-1-formyl-3-hydroxymethylenecyclohexene derivatives {alkyl = H (22), Me (23)} with in situ generated disodium diselenide (Na 2 Se 2 ). However, when 2-chloro-1formyl-3-hydroxymethylenecyclohexene, 22 is condensed with aniline or 4-methoxyaniline and the resulting Schiff bases 26 and 27 are subjected to identical reactions, the Schiff bases undergo cyclisation to afford brightly colored, fused 1,6-diaza-6a-selenapentalene derivatives 28-29, instead of the expected selenospirocycles. The aromatic nucleophilic substitution (S N Ar) reaction of N-(2-bromo-3-nitrobenzyl) naphthylamine, 33 with n BuSeLi affords N-[2-(butylselanyl)-3nitrobenzyl]naphthylamine, 34. The bromination of 34 results in the formation of cyclic isoselenazolines, 35. Selenospirocycles 24 and 25, 1,6-diaza-6a-selenapentalenes 28 and 29 and isoselenazoline 35 are authenticated by single-crystal Xray diffraction studies. Compounds 24, 25 and 35 are stabilized by intramolecular secondary interactions.[a] Dr. Se NMR resonance appears at 931 ppm which is in close agreement with the reported isoselenazoline derivatives. [5] UV-Visible StudiesThe UV-visible studies for ligand 26 and heterocycles 28, 30 were recorded at 15 × 10 À 6 M concentration in acetonitrile as solvent at the room temperature ( Figure 5). All the compounds Figure 4. Plausible mechanism for the formation of 30. Scheme 5. Synthesis of isoselenazoline 35.

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Spirodiazaselenuranes: synthesis, structure and antioxidant activity

Cited by 35 publications

References 67 publications

Substituent Effects on the Stability and Antioxidant Activity of Spirodiazaselenuranes

Substituent Effects on the Stability and Antioxidant Activity of Spirodiazaselenuranes

Enzyme Mimetic Chemistry of Organoselenium Compounds

Contrasting Reactivity of 2‐chloro‐1‐formyl‐3‐hydroxymethylenecyclohexene and its Schiff Bases towards Disodium Diselenide: Isolation of Selenospirocycles versus Azapentalenes

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