Synthesis of Selenoflavones via Ruthenium-Catalyzed Selenylation of Unsaturated Acids

An efficient method for pharmaceutically useful selenoflavones via a ruthenium-catalyzed selenylation reaction is demonstrated. The ruthenium-catalyzed selenylation was applied to synthesize diverse alkenyl selenides from simple unsaturated acids/amides and diaryl diselenides. A wide range of differently substituted diaryl diselenides can be applied in this protocol with a good functional group with excellent stereo- and regioselectivity.

Anticancer-active 3,4-diarylthiolated maleimides synthesis via three-component radical diarylthiolation

Herein, we report an efficient and simple copper-catalyzed oxidative diarylthiolation of maleimides with sulfur powder and aryl boronic acids, in which S powder was used as a substrate and internal oxidant. The corresponding double C-S bonds coupling products were obtained in moderate to high yields under a simple catalytic system. Mechanistic studies indicated that copper-catalyzed radical thiolation of aryl boronic acids with S powder, and the resulting arylthiyl underwent radical addition with double bonds of maleimides.

Recent Advances in Light-Induced Selenylation

Selenium-containing organic molecules have recently found a plethora of applications, ranging from organic synthesis to pharmacology and material sciences. In view of these concepts, the development of mild, efficient, and general protocols for the formation of C-Se bonds is desirable, and light induced approaches are appealing ways. The aim of this Review is to provide the reader with the most recent examples of light promoted selenylation processes.

Synthesis of 1,2-diselenides via potassium persulfate-mediated diselenation of allenamides with diselenides

An efficient potassium persulfate-mediated radical addition of allenamides with diselenides was developed to create a workable route to 1,2-diselenide products. The reaction tolerates a wide spectrum of functional groups to deliver the products in good to excellent yields. Mechanistic investigations including a calculation study indicated that the radical cascade proceeds through a vinyl radical intermediate, which is formed via a selenium radical added to the terminal CC double bond of allenamides.

Selenium Dihalides Click Chemistry: Highly Efficient Stereoselective Addition to Alkynes and Evaluation of Glutathione Peroxidase-Like Activity of Bis(E-2-halovinyl) Selenides

Highly efficient stereoselective syntheses of novel bis(E-2-chlorovinyl) selenides and bis(E-2-bromovinyl) selenides in quantitative yields by reactions of selenium dichloride and dibromide with alkynes were developed. The reactions proceeded at room temperature as anti-addition giving products exclusively with (E)-stereochemistry. The glutathione peroxidase-like activity of the obtained products was estimated and compounds with high activity were found. The influence of substituents in the products on their glutathione peroxidase-like activity was discussed.

Hydroelementation of diynes

This review highlights the hydroelementation reactions of conjugated and separated diynes, which depending on the process conditions, catalytic system, as well as the type of reagents, leads to the formation of various products: enynes, dienes, allenes, polymers, or cyclic compounds. The presence of two triple bonds in the diyne structure makes these compounds important reagents but selective product formation is often difficult owing to problems associated with maintaining appropriate reaction regio- and stereoselectivity. Herein we review this topic to gain knowledge on the reactivity of diynes and to systematise the range of information relating to their use in hydroelementation reactions. The review is divided according to the addition of the E-H (E = Mg, B, Al, Si, Ge, Sn, N, P, O, S, Se, Te) bond to the triple bond(s) in the diyne, as well as to the type of the reagent used, and the product formed. Not only are the hydroelementation reactions comprehensively discussed, but the synthetic potential of the obtained products is also presented. The majority of published research is included within this review, illustrating the potential as well as limitations of these processes, with the intent to showcase the power of these transformations and the obtained products in synthesis and materials chemistry.

(Z,Z)-Selanediylbis(2-propenamides): Novel Class of Organoselenium Compounds with High Glutathione Peroxidase-Like Activity. Regio- and Stereoselective Reaction of Sodium Selenide with 3-Trimethylsilyl-2-propynamides

The efficient regio- and stereoselective synthesis of (Z,Z)-3,3′-selanediylbis(2-propenamides) in 76–93% yields was developed based on the reaction of sodium selenide with 3-trimethylsilyl-2-propynamides. (Z,Z)-3,3′-Selanediylbis(2-propenamides) are a novel class of organoselenium compounds. To date, not a single representative of 3,3′-selanediylbis(2-propenamides) has been described in the literature. Studying glutathione peroxidase-like properties by a model reaction showed that the activity of the obtained products significantly varies depending on the organic moieties in the amide group. Divinyl selenide, which contains two lipophilic cyclohexyl substituents in the amide group, exhibits very high glutathione peroxidase-like activity and this compound is considerably superior to other products in this respect.

Hexafluoroisopropanol-Promoted Disulfidation and Diselenation of Alkyne, Alkene, and Allene

Hexafluoroisopropanol (HFIP)-promoted disulfidation and diselenation of C-C unsaturated bonds is reported. Reactions of unactivated alkyne, alkene, and allene, respectively, with disulfides or diselenides in HFIP led to desired products in good to excellent yields (up to 96%). In contrast, other solvents, such as isopropanol and dichloroethane, could not promote the same reaction. This method revealed an example of HFIP-promoted transformations under the mild conditions, which greatly highlighted the unique reactivity of this special solvent.

Atom Transfer Oxidative Radical Cascade of Aryl Alkynoates towards 1,1-Dichalcogenide Olefins

An oxidative trifunctionalization of aryl alkynoates has been devised via the chalcogenide radical triggered intramolecular 1,4-aryl migration/decarboxylation cascade to prepare 1,1-dichalcogenide tetrasubstituted alkenes in high yields (up to 98 %). This operationally simple reaction proceeds under metal-free conditions, can be executed on gram scale, and highlights formal 1,1-difunctionalization of alkynes. Synthetic potential of this protocol was demonstrated through a twofold cascade rearrangement to access highly conjugated tetra-selenylated alkenes along with a cross-dehydrogenative annulation to prepare fluorene derivative.

Efficient Protocol for Synthesis of β-Hydroxy(alkoxy)selenides via Electrochemical Iodide-Catalyzed Oxyselenation of Styrene Derivatives with Dialkyl(aryl)diselenides

An efficient protocol for the synthesis of β-hydroxy(alkoxy)selenides was developed through the electrochemical iodide-catalyzed oxyselenation of styrene derivatives with dialkyl(aryl)diselenides under mild reaction conditions. Mechanistic studies showed that the cation I+ is involved during the whole process, and accelerates the formation of seleniranium ion via substitution and addition reaction with dialkyl(aryl)diselenides and styrene derivatives. The corresponding products are formed in good to excellent yields. This electrochemical oxyselenation provides an efficient strategy for difunctionalization of alkenes.

Metal-free difunctionalization of alkynes to access tetrasubstituted olefins through spontaneous selenosulfonylation of vinylidene ortho-quinone methide (VQM)

A metal-free protocol for difunctionalization of alkynes through spontaneous selenosulfonylation of vinylidene ortho-quinone methide (VQM) was developed with good yields and excellent stereoselectivities.

Copper(i)/succinic acid cooperatively catalyzed one-pot synthesis of organoselenium-propargylamines via A3-coupling

Selenium propargylamines were synthesized via an A³-coupling approach using piperidine, p-methoxybenzaldehyde, and trimethylsilyl selenium–acetylene, catalyzed by copper(i) chloride and succinic acid as an additive, in good to excellent yields.

Formation of α-chalcogenyl acrylamides through unprecedented chalcogen-mediated metal-free oxyfunctionalization of ynamides with DMSO as an oxidant

A novel chalcogen-mediated metal-free oxyfunctionalization mode of ynamides for the synthesis of α-chalcogenyl acrylamides has been developed.

Metal-free radical thiolations mediated by very weak bases

A radical aromatic substitution mechanism initiated by very weak bases effects the synthesis of thioethers and heavier chalcogenides.

Stereoselective synthesis of alkyl styryl selenides in one-pot: a straightforward approach by in situ dialkyl diselenide formation under transition metal-free conditions

One-pot synthesis of alkyl styryl selenides using KSeCN as selenium source.