Diorganyl Diselenides Research Articles

Silver-Mediated Acetoxyselenylation of Alkynes: Mild Stereoselective Access to Bifunctional Alkenes.

Herein, we report a AgF-mediated regio- and stereoselective acetoxyselenylation of terminal/internal alkynes from iodobenzene dicarboxylate [PhI(OCOR)2] and diorganyl diselenides via multiple-site functionalization to afford β-selenyl enol esters in good yields. Alkynes derived from bioactive molecules, such as l(-)-borneol, l-menthol, and acyne oxalate, are also suitable for this transformation and afford the expected compounds.

Synthesis of 5-Seleno-Substituted Spirocyclopenta[b]pyridine-2,5-dien-4-ones and Benzo[h]quinolines via Radical Cyclization of Arylethynylpyridines.

A practical strategy for obtaining novel 5-seleno-substituted spirocyclopenta[b]pyridines-2,5-dien-4-ones and benzo[h]quinolines via radical cyclization is reported. The synthetic protocol explores the reaction between arylethynylpyridines and diorganyl diselenides in acetonitrile as solvent and Oxone® as oxidant at 82 °C. This easy-to-handle, eco-friendly metal-free approach was carried out under an open atmosphere, affording functionalized organoselenium compounds in good to excellent yields. Control experiments and scale-up test were performed to demonstrate the efficiency of this methodology.

Micelle-Assisted C(sp2)-H Functionalization for C-Se and C-X Bond Formation in the Aqueous Medium.

An environmentally sustainable, versatile, and cost-effective approach for C-Se and C-X (X = I, Br, and Cl) bond formation through C-H functionalization assisted by micellar catalysis in water is developed. The reaction utilizes a minimum amount of diorganyl diselenides and potassium halides for the respective functionalizations. The present protocol was suitable for scale-up synthesis, which directly provided the desired selenylated products without the need for chromatographic purification, in sufficient purity. The aqueous micellar catalysis system was reusable for up to 5 reaction cycles without compromising the reaction yield.

Selenylated Analogs of Tacrine: Synthesis, In Silico and In Vitro Studies of Toxicology and Antioxidant Properties.

We present our results on the synthesis and preliminary in silico and in vitro studies of the toxicology and antioxidant properties of selenylated analogs of Tacrine. Initially, we synthesized 2-aminobenzonitriles containing an organic selenium moiety, resulting in sixteen compounds with various substituents linked to the portion derived from diorganyl diselenide. These compounds were then used as substrates in reactions with cyclic ketones, in the presence of 1.4 equivalents of trifluoroboroetherate as a Lewis acid, to synthesize selenylated analogs of Tacrine with yields ranging from 20 % to 87 %. In silico studies explored computational parameters related to antioxidant activity and hepatotoxicity. In vitro studies elucidated the antioxidant effects of Tacrine and its selenium hybrid (TSe) in neutralizing ABTS radicals, scavenging DPPH radicals, and reducing iron ions. Additionally, the acute oral toxicity of one synthesized compound was evaluated.

Recent Progress in Synthetic and Biological Application of Diorganyl Diselenides.

Diorganyl diselenides have emerged as privileged structures because they are easy to prepare, have distinct reactivity, and have broad biological activity. They have also been used in the synthesis of natural products as an electrophile in the organoselenylation of aromatic systems and peptides, reductions of alkenes, and nucleophilic substitution. This review summarizes the advancements in methods for the transformations promoted by diorganyl diselenides in the main functions of organic chemistry. Parallel, it will also describe the main findings on pharmacology and toxicology of diorganyl diselenides, emphasizing anti-inflammatory, hypoglycemic, chemotherapeutic, and antimicrobial activities. Therefore, an examination detailing the reactivity and biological characteristics of diorganyl diselenides provides valuable insights for academic researchers and industrial professionals.

Electrophotocatalysis Versus Indirect Electrolysis: Electrochemical Selenocyclization of 3-Aza-1,5-dienes Facilitated by Energy Transfer, Direct Photolysis or N-Hydroxyphthalimide.

Three hybrid electrochemical protocols, which involve the energy transfer, direct photolysis and N-hydroxyphthalimide catalyst, respectively, are presented for the selenylation/cyclization of the fragile substrates of 3-aza-1,5-dienes with diorganyl diselenides to afford 3-selenomethyl-4-pyrrolin-2-ones. The two electrophotocatalytic reactions and the indirect electrolysis one are both regioselective and external-oxidant- and transition-metal-free, and are associated with a broad substrate scope and high Se-economy, and all three methods are amenable to gram-scale syntheses, late-stage functionalizations, sunlight-induced experiments and all-solar-driven syntheses.

Synthesis of 9,10‐Bis(organochalcogenyl)phenanthrenes by Cyclization of (Biphenyl‐2‐alkyne)chalcogenides

AbstractA regioselective, operationally simple and scalable protocol was developed for the synthesis of 9,10‐bis(organochalcogenyl)phenanthrenes and seleno‐spiro[cyclohexane‐1,1′‐indene]‐2,5‐dien‐4‐ones through the cyclization of (biphenyl‐2‐alkyne)chalcogenides. The reaction occurs in the presence of diorganyl diselenides, Oxone® as a green oxidizing agent, and acetonitrile at 80 °C. In this study, 20 compounds were obtained in yields of up to 97 % and in short reaction times (1–4 h).

Telescoping Synthesis of 4-Organyl-5-(organylselanyl)thiazol-2-amines Promoted by Ultrasound.

In this work, we describe the synthesis of new 4-organyl-5-(organylselanyl)thiazol-2-amine hybrids through a one-pot two-step protocol. The transition metal-free method involves the use of ultrasound as an alternative energy source and Oxone® as oxidant. To obtain the products, a telescoping approach was used, in which 4-organylthiazol-2-amines were firstly prepared under ultrasonic irradiation, followed by the addition of diorganyl diselenides and Oxone®. Thus, 16 compounds were prepared, with yields ranging from 61 % to 98 %, using 2-bromoacetophenone derivatives and diorganyl diselenides as easily available starting materials.

Metal‐free regioselective selenylation of β‐napthol derivatives promoted by trichloroisocyanuric acid

AbstractA new approach for synthesizing selenylated naphthalene derivatives is described herein, employing trichloroisocyanuric acid (TCCA) as the oxidizing agent. The developed protocol yielded 18 compounds, with yields ranging from 32 % to 90 %. Additionally, the reaction was conducted under mild conditions, utilizing ethanol as the solvent at room temperature, demonstrating good atom economy. The key aspect of the protocol is the in situ generation of electrophilic selenium species through the reaction of diorganyl diselenides and TCCA.

Selective Access to Functional Fluoroenones via Palladium-Catalyzed Selenofluoroalkylacylation of Terminal Alkynes.

The trifluoromethylacyl group (-COCF3) is an important motif and widely studied in catalysis, medicinal chemistry, and materials science. Herein, a novel palladium-catalyzed selenofluoroalkylacylation of terminal alkynes with commercially available fluoroalkyl anhydride and diorganyl diselenides to afford β-seleno and aryl/alkyl disubstituted enones under mild conditions is disclosed. In addition, selenodifluoroacetylations and selenoperfluoroacetylations are also suitable for this reaction. Mechanistic studies reveal that this reaction proceeds via an oxidative radical-polar crossover process.

Studies on the selective synthesis of diorganyl diselenides using potassium hydroxide and mechanistic investigations of the reaction pathway.

Methods of selectively synthesizing diorganyl diselenides (R-Se-Se-R) without using harmful reducing agents are presented. We optimized the reaction conditions for the selective formation of the diselenide dianion (Se22-) and the corresponding diorganyl diselenides using basic reagents (e.g., KOH), while suppressing the formation of side products, such as diorganyl selenides (R-Se-R) or multiselenides (R-Sen-R; n ≥ 3). Furthermore, we have suggested and examined the reaction pathways responsible for the formation of the desired diorganyl diselenides 1 and side products 2 and 3. Consequently, the selective synthesis of diverse diorganyl diselenides was achieved with modest to excellent yields (33-99%) using various organyl halides under optimized conditions. The results provide a practical and efficient synthetic method for diorganyl diselenides as a representative class of organoselenium compounds.

Electrochemically promoted selenocyclization for the synthesis of organoselenyl isoxazoles

Herein, we report a general and sustainable electrochemically promoted oxidative selenocyclization protocol for the synthesis of organoselenyl isoxazoles from 2-alkyn-1-one O-methyloximes and diorganyl diselenides.

Advances in Difunctionalization of Olefins with Diorganyl Dichalcogenides.

Organochalcogen molecules have extensive applications in various fields. They serve as pharmaceuticals, ligands, organocatalysts, agrochemicals, and other functional materials. Difunctionalization of olefins, which belong to a class of multicomponent reactions, is a successful technique for introducing two functional moieties in a single-step reaction, both in terms of atom economy and step economy. The difunctionalization of olefins with diorganyl dichalcogenides may effectively increase the molecular complexity, which has achieved significant advancements in recent decades. This article describes recent advancements in the difunctionalization of olefins with diorganyl diselenides and diorganyl disulfides.

Selective Synthesis of Symmetrical Thiosulfonates via Oxidative Coupling of Thiols Catalyzed by Diorganyl Diselenide

AbstractA straightforward methodology for the synthesis of symmetrical thiosulfonates through direct oxidative coupling of thiols is reported. Dibutyl diselenide was suitably applied as a catalyst for the selective conversion of thiols into respective thiosulfonates in good yields. Moreover, mechanistic studies revealed a radical reaction pathway for the preparation of target products.

Urea Hydrogen Peroxide and Ethyl Lactate, an Eco-Friendly Combo System in the Direct C(sp2)-H Bond Selenylation of Imidazo[2,1-b]thiazole and Related Structures.

Herein, we describe a urea hydrogen peroxide-mediated sustainable protocol for the synthesis of selenylated imidazo[2,1-b]thiazole by using half molar equivalent diorganyl diselenides in ethyl lactate as a greener solvent. The reaction features high yields, easy performance on gram scale, metal-free conditions, as well as applicability to imidazopyridine and imidazopyrimidine.

Recent Advances in the Use of Diorganyl Diselenides as Versatile Catalysts.

The importance of organoselenium compounds has been increasing in synthetic chemistry. These reagents are well-known as electrophiles and nucleophiles in many organic transformations, and in recent years, their functionality as catalysts has also been largely explored. The interest in organoselenium-based catalysts is due to their high efficacy, mild reaction conditions, strong functional compatibility, and great selectivity. Allied to organoselenium catalysts, the use of inorganic and organic oxidants that act by regenerating the catalytic species for the reaction pathway is common. Here, we provide a comprehensive review of the last five years of organic transformations promoted by diorganyl diselenide as a selenium-based catalyst. This report is divided into four sections: (1) cyclisation reactions, (2) addition reactions and oxidative functionalisation, (3) oxidation and reduction reactions, and (4) reactions involving phosphorus-containing starting materials.

White Light/NIS‐Promoted Aminoselenylation of Alkenes by Using N‐Tosylhydrazones

AbstractA white light/iodosuccinimide (NIS)‐promoted three component reaction of alkenes, N‐sulfonylhydrazones, and diorganyl diselenides for synthesis of organylselenylethyl sulfonylhydrazones under air is disclosed. This intermolecular aminoselenylation of alkenes using N‐tosylhydrazones as nitrogen source was performed under mild conditions and well tolerated for common groups. In addition, heteroaryl and aliphatic diselenides also gave the target compounds. Gram‐scale reaction also carried out smoothly. This protocol has a wide range of substrates and affords moderate to high yields and excellent regioselectivities. The photoactive intermediates from the interaction between NIS and diphenyl diselenide was detected by UV‐visible absorption spectra, which matches the wavelength of the applied white LED. A reasonable mechanism was proposed based on UV‐visible light experiments and control experiments.

Direct and Regioselective C−H Selenylation of 4‐Aminocoumarin Derivatives Mediated by Selectfluor®

AbstractA mild and regioselective approach to the direct selenylation of 4‐(N‐substituted‐amino)‐2H‐chromen‐2‐ones employing Selectfluor® and diorganyl diselenides has been developed. The reactions were carried out under metal‐free conditions, without the need for special devices, and using NaHCO3 as a mild base at room temperature under air. This approach has been suitable for a wide substrate scope affording the 3‐selenyl‐4‐(N‐substituted‐amino)‐2H‐chromen‐2‐ones in good to excellent yields.

Electrophile-Promoted Nucleophilic Cyclization of 2-Alkynylindoles to Give 4-Substituted Oxazinoindolones.

A method for the synthesis of 4-organoselanyl oxazinoindolone derivatives by the cascade cyclization of N-(alkoxycarbonyl)-2-alkynylindoles using iron(III) chloride and diorganyl diselenides as promoters was developed. This protocol was applied to a series of N-(alkoxycarbonyl)-2-alkynylindoles containing different substituents. The reaction conditions also tolerated a variety of diorganyl diselenides having both electron donating and electron withdrawing groups. However, the reaction did not work for diorganyl disulfides and ditellurides. The reaction mechanism seems to proceed via an ionic pathway and the cooperative action between iron(III) chloride and diorganyl diselenides is crucial for successful cyclization. We also found that using the same starting materials, by simply changing the electrophilic source to iodine, led to the formation of 4-iodo-oxazinoindolones. The high reactivity of Csp2 -Se and Csp2 -I bonds were tested under cross-coupling conditions leading to the preparation of a new class of functionalized indole derivatives. In addition, the absorption, emission and electrochemical properties of 4-organoselanyl oxazinoindolones showed an important relationship with the substituents of the aromatic rings. The advantages of the methodology include the use of electrophilic to promote the cyclization reaction and functionalization of the indole ring, and the electronic properties presented by the prepared compounds can be exploited as probes, analyte detectors and optical materials.

Synthesis of Chalcogenylchromenes through Cyclization of Propargylic Aryl Ethers.

We describe here for the first time the synthesis of 2-(chalcogenyl)-3H-benzo[f]chromenes and the new 3-(phenylselanyl)-2H-chromenes by the radical or electrophilic cyclization of propargylic aryl ethers in the presence of diorganyl diselenides or ditellurides using Oxone as a green oxidant and acetonitrile as solvent in a sealed tube at 100 °C. In this study, thirty-one chalcogenylchromenes with a broad substrate scope were prepared in moderate to excellent yields (50-98%), including compounds derived from natural products.