KF/Al2O3 and PEG-400 as a recyclable medium for the selective α-selenation of aldehydes and ketones. Preparation of potential antimicrobial agents

Recent Advances in the Synthesis and Antioxidant Activity of Low Molecular Mass Organoselenium Molecules

Selenium is an essential trace element in living organisms, and is present in selenoenzymes with antioxidant activity, like glutathione peroxidase (GPx) and thioredoxin reductase (TrxR). The search for small selenium-containing molecules that mimic selenoenzymes is a strong field of research in organic and medicinal chemistry. In this review, we review the synthesis and bioassays of new and known organoselenium compounds with antioxidant activity, covering the last five years. A detailed description of the synthetic procedures and the performed in vitro and in vivo bioassays is presented, highlighting the most active compounds in each series.

Metal-Free Three-Component Coupling Reaction of Ketones with Electron-rich Arenes and Selenium Dioxide for the Synthesis of α-Arylselanyl Ketones

A metal-free three-component coupling reaction of aryl alkyl/alkyl ketones, SeO₂, and phenols/anisoles is described. This multicomponent reaction provides a straightforward and facile pathway for the synthesis of α-((4-hydroxy/methoxyphenyl)selanyl)-aryl alkyl/alkyl ketones in the presence of p-toluenesulfonic acid for the C-Se bond formation process. The method offers an attractive and simple procedure using commonly available shelf reagents to deliver organoselenides that, to our knowledge, are being reported here for the first time.

K2S2O8-promoted C-Se bond formation to construct α-phenylseleno carbonyl compounds and α,β-unsaturated carbonyl compounds

A novel K₂S₂O₈-promoted C–Se bond formation from cross-coupling under neutral conditions has been developed. A variety of aldehydes and ketones react well using K₂S₂O₈ as the oxidant in the absence of catalyst and afford desired products in moderate to excellent yields. This protocol provides a very simple route for the synthesis of α-phenylseleno carbonyl compounds and α,β-unsaturated carbonyl compounds.

K₂S₂O₈-promoted C–Se bond formation from the cross-coupling of C(sp³)–H bond adjacent to carbonyl group with diphenyl diselenide under metal-free conditions.

Photoinduced metal-free α-selenylation of ketones

Herein, we report an efficient photoinduced α-selenylation of ketones without metal, additives or under photosensitizer-free conditions, providing a green protocol using light energy to synthesize a variety of α-selenoketones. This new methodology proved to be a mild, simple and eco-friendly tool for the efficient synthesis of the desired products.

Herein, we report an efficient photoinduced α-selenylation of ketones without metal, additives or under photosensitizer-free conditions, providing a green protocol using light energy to synthesize a variety of α-selenoketones.

(Oxo)(Fluoro)-Aluminates in KF-Al2O3 System: Thermal Stability and Structural Correlation

Precise investigation of part of the phase diagram of KF-Al₂O₃ system was performed in an experiment combining different techniques. Solidified mixtures of KF-Al₂O₃ were studied by X-ray powder diffraction and high-field solid-state NMR spectroscopy over a wide range of compositions. To help with the interpretation of the NMR spectra of the solidified samples found as complex admixtures, we synthesized the following pure compounds: KAlO₂, K₂Al₂₂O₃₄, α-K₃AlF₆, KAlF₄, and K₂Al₂O₃F₂. These compounds were then characterized using various solid-state NMR techniques, including MQ-MAS and D-HMQC. NMR parameters of the pure compounds were finally determined using first-principles density functional theory calculations. The phase diagram of KF-Al₂O₃ with the alumina content up to 30 mol % was determined by means of thermal analysis. Thermal analysis was also used for the description of the thermal stability of one synthesized compound, K₂Al₂O₃F₂.

Ring-opening selenation of cyclobutanols: synthesis of γ-selenylated alkyl ketones through C–C bond cleavage

An efficient, practical, and operationally simple manganese-mediated ring-opening selenation of cyclobutanols is disclosed.

Antinociceptive properties of new coumarin derivatives bearing substituted 3,4-dihydro-2H-benzothiazines

Background

Coumarins are an important class of widely distributed heterocyclic natural products exhibiting a broad pharmacological profile. In this work, a new series of coumarins bearing substituted 3,4-dihydro-2H-benzothiazines were described as potential analgesic agents. The clinical use of NSAIDs as traditional analgesics is associated with side effects such as gastrointestinal lesions and nephrotoxicity. Therefore, the discovery of new safer drugs represents a challenging goal for such a research area.

Results

The target compounds 3-(3-methyl-3,4-dihydro-2H-benzo[b][1,4]thiazin-3-yl)-2H-chromen-2-ones 2a-u were synthesized and characterized by spectral data. The antinociceptive properties of target compounds were determined by formalin-induced test and acetic acid-induced writhing test in mice. Among the tested compounds, compound 2u bearing 2-(4-(methylsulfonyl)benzoyl)- moiety on benzothiazine ring and 4-(methylsulfonyl)phenacyloxy- group on the 7 position of coumarin nucleus showed better profile of antinocecieption in both models. It was more effective than mefenamic acid during the late phase of formalin-induced test as well as in the acetic acid-induced writhing test.

Conclusion

Considering the significant antinoceciptive action of phenacyloxycoumarin derivatives, compound 2u prototype might be further used as model to obtain new more potent analgesic drugs.

“The green side of the moon: ecofriendly aspects of organoselenium chemistry”

Key aspects for the development of a greener synthesis and the use of the organoselenium compounds.

In vitro antioxidant activity and in vivo antidepressant-like effect of α-(phenylselanyl) acetophenone in mice

In this study, the antioxidant and antidepressant-like effects of α-(phenylselanyl) acetophenone (PSAP), an organoselenium compound, were investigated. To assess the in vitro antioxidant properties, PSAP was evaluated in four test systems (DPPH, ABTS, FRAP and inhibition of lipid peroxidation). PSAP (100-500 μM) showed potent antioxidant activity and protected against lipid peroxidation. Additionally, we investigated whether PSAP, when administered in mice (100, 200 and 400mg/kg, per oral, p.o.), could cause acute toxicity. Our results demonstrated that PSAP did not cause the death of any animal, significantly reduce body weight or cause any oxidative tissue stress following treatment. This study also evaluated the effect of PSAP (0.1-10 mg/kg, p.o) on mice in a forced swim test (FST) and tail suspension test (TST), assays that are predictive of depressant activity and motor activity in the open-field. PSAP (5-10 mg/kg) significantly reduced immobility time in the FST and TST without affecting motor activity. In addition, the antidepressant-like effect caused by PSAP (5m/kg, p.o) in mice during the TST was dependent on an interaction with the serotonergic system (5-HT(1A) receptors), but not with the noradrenergic, dopaminergic or adenosinergic system. Together, these results suggest that PSAP possesses antioxidant and antidepressant-like properties and may be of interest as a therapeutic agent for the treatment of depressive disorders.