Regio- and stereoselective electrochemical selenoalkylation of alkynes with 1,3-dicarbonyl compounds and diselenides

A regio- and stereoselective electrochemical approach for the selenoalkylation of alkynes with 1,3-dicarbonyl compounds and diselenides has been developed.

Ni and Fe Catalyzed Cascade Radical Reactions of Oxime Esters with Diselenides

A radical cyclization and ring-opening of oxime esters with diselenides was developed. Both Ni(0) and Fe(II) catalysts could be employed for the selenylation of olefin-containing and cyclic oxime ester derivatives....

Metal-free regioselective cascade sulfonylation-cyclization of 3-aza-1,5-enynes with sulfur dioxide and aryldiazonium tetrafluoroborates to construct 1,2-dihydropyridines

Radical cascade cyclization of tethered alkynes has emerged as an efficient tool to construct small but complex cyclic compounds. However, it currently relies on aryl or heteroaryl-tethered alkynes to give...

Electrochemical oxidative cyclization of alkenes, boronic acids, and dichalcogenides to access chalcogenated boronic esters and 1,3-diols

A sustainable, environmentally benign electrochemical oxidative three-component cyclization of allylic alcohols, boronic acids, and dichalcogenides under metal-free and oxidant-free conditions has been developed.

(NH4)2S2O8-Promoted cross-coupling of thiols/diselenides and sulfoxides for the synthesis of unsymmetrical disulfides/selenosulfides

(NH4)2S2O8-Promoted cross-coupling of thiols/diselenides and sulfoxides to construct unsymmetrical disulfides/selenosulfides is disclosed. Control experiments demonstrate that (NH4)2S2O8 acts as an acid and an oxidant while both ionic and radical routes...

Radical-mediated carboselenation of terminal alkynes under mild conditions

Metal-free radical carboselenation of terminal alkynes is developed for the synthesis of (E)-γ-seleno-substituted allyl nitriles with excellent regioselectivity and stereoselectivity.

Electrochemical oxidative selenocyclization of olefinic amides towards the synthesis of iminoisobenzofurans

We introduced an electrochemical oxidative radical cascade cyclization of olefinic amides and diselenides without a transition-metal catalyst and external oxidant. This selenocyclization reaction provided a facile method to construct C–Se and C–O bonds in one step.

Preparation of selenyl 1,3-oxazines via PhICl2/Cu2O-promoted aminoselenation of O-homoallyl benzimidates with diselenides

A practical electrophilic aminoselenation of O-homoallyl benzimidate with diselenides promoted by PhICl₂/Cu₂O has been developed. The easily available and stable diselenides were used as selenium sources. Various selenyl 1,3-oxazines, which are important frameworks in medicinal and biological chemistry, were easily obtained in moderate to good yields for the first time. Easy scaleup and scalability make this method attractive for the preparation of other valuable organoselenides.

Synthesis of Polysubstituted Furans through Electrochemical Selenocyclization of Homopropargylic Alcohols

The current method represents an electrochemically driven synthetic route to access polysubstituted selenofuran derivatives through the diselenide-promoted cyclization of homopropargyl alcohols. The tandem electro-oxidative transformation operates at ambient temperature and in the absence of an external oxidant. This mild and efficient methodology exhibits good functional group compatibility, providing a broad range of substrate scopes up to 84% isolated yield. Further conversion of the seleno-functionality afforded other valuable furan derivatives.

Highly Diastereoselective Synthesis of Dihydro-benzoimidazo-[1,3]-thiazines via Electro-oxidative Selenocyclization of Thioallyl Benzoimidazoles

The current methodology reveals a green and proficient electro-oxidative tandem selenocyclization of thioallyl benzoimidazoles manufacturing selenylated dihydro-benzoimidazo-thiazine derivatives. Both C-Se and C-N bond formation were achieved via this mild protocol which exhibits good functional group tolerability affording an extensive range of substrate scope up to 96% isolated yields. Complete control over the regioselective formation of the six-membered heterocycle and stereoselective construction of the contiguous stereocenters was established. The practical electrochemical method operates in an undivided cell at ambient temperature without using any metal and external chemical oxidant.

Diorganyl diselenides: a powerful tool for the construction of selenium containing scaffolds

Organoselenium compounds find versatile applications in organic synthesis, materials synthesis, and ligand chemistry. Organoselenium heterocycles are widely studied agents with diverse applications in various biological processes. This review highlights the recent progress in the synthesis of selenium heterocycles using diorganyl diselenides with keen attention on green synthetic approaches, scopes, C-H selanylation, the mechanisms of different reactions and insights into the formation of metal complexes. The C-H selanylation using diorganyl diselenides with different catalysts, bases, transition metals, iodine salts, NIS, hypervalent iodine, and other reagents is summarised. Finally, the diverse binding modes of bis(2/4-pyridyl)diselenide with different metal complexes are also summarised.

Palladium-catalyzed bisthiolation of terminal alkynes for the assembly of diverse (Z)-1,2-bis(arylthio)alkene derivatives

An efficient and straightforward palladium-catalyzed three-component cascade bisthiolation of terminal alkynes and arylhydrazines with sodium thiosulfate (Na₂S₂O₃) as the sulfur source for the assembly of functionalized (Z)-1,2-bis(arylthio)alkene derivatives is described. Using 0.5 mol% IPr–Pd–Im–Cl₂ as the catalyst, a wide range of terminal alkynes and arylhydrazines are well tolerated, thus producing the desired products in good yields with good functional group tolerance and excellent regioselectivity. Moreover, this protocol could be readily scaled up, showing potential applications in organic synthesis and material science.

An efficient palladium-catalyzed bisthiolation of terminal alkynes and arylhydrazines with Na₂S₂O₃ as the sulfur source for the assembly of (Z)-1,2-bis(arylthio)alkene derivatives is described.

Electrochemical synthesis of sulfonated benzothiophenes using 2-alkynylthioanisoles and sodium sulfinates

Electrochemical sulfonylation/cyclization of 2-alkynylthioanisoles with sodium sulfinates was developed under catalyst-, external oxidant- and metal-free conditions. The electrosynthesis provides sustainable and efficient access to 3-sulfonated benzothiophenes with good substrate scope and functional group tolerance. This cascade radical process has been triggered through a sulfonyl radical addition to alkynes using sodium sulfinates under electrochemical conditions.

Synthesis of selenated tetracyclic indoloazulenes via iodine and diorganyl diselenides

Herein, we report an efficient protocol for the synthesis of selenated tetracyclic indoloazulenes. The reaction of diorganyl diselenides with molecular iodine in dichloromethane leads to the in situ formation of organo selenenyl iodide. The synthesis of selenylated tetracyclic indoloazulenes through intramolecular cascade cyclization has been achieved via organo selenenyl iodide and bisindole at room temperature under metal-free conditions in good yields. All compounds were fully characterized by the FT-IR, HRMS, and ¹H, ¹³C and ⁷⁷Se NMR spectral data.

Diorganyl Dichalcogenides and Copper/Iron Salts: Versatile Cyclization System To Achieve Carbo- and Heterocycles from Alkynes

Organochalcogen-containing cyclic molecules have shown several promising pharmacological properties. Consequently, different strategies have been developed for their synthesis in the past few years. Particularly due to the low cost and environmental aspects, copper- and iron-promoted cyclization reactions of alkynyl substrates have been broadly and efficiently applied for this purpose. This short review presents an overview of the most recent advances in the synthesis of organochalcogen-containing carbo- and heterocycles by reacting diorganyl disulfides, diselenides, and ditellurides with alkyne derivatives in the presence of copper and iron salts to promote cyclization reactions.

1 Introduction

2 Synthesis of Carbo- and Heterocycles via Reactions of Alkynes with Diorganyl Dichalcogenides and Copper Salts

3 Synthesis of Carbo- and Heterocycles via Reactions of Alkynes with Diorganyl Dichalcogenides and Iron Salts

4 Conclusions

Copper-catalyzed radical cascade cyclization for synthesis of CF3-containing tetracyclic benzimidazo[2,1-a]iso-quinolin-6(5H)-ones

Here, a general copper-catalyzed radical cascade carbocyclization reaction with 2-arylbenzoimidazoles and a Togni reagent was realized. Structurally diverse CF3-containing tetracyclic core benzimidazo[2,1-a]isoquinoline-6(5H)-ones were obtained in moderate to good yields. The wide substrate scope, good functional group tolerance, and ease of scale-up of this method are expected to promote its potential applications in pharmacy and biotechnology.

Visible-Light Mediated Diarylselenylative Cyclization of 1,6-Enynes

We herein described a selenylative cyclization reaction of enynes by the utilization of diselenides as radical sources. The visible-light irradiation of the reaction mixture enables the generation of the selenium atom radical to trigger the radical addition/cyclization/selenation sequences. Both terminal alkyne and internal alkyne derived 1,6-enynes were tested and suitable for the current synthetic protocol, delivering various kinds of selenium-containing cycles in good yields.

Recent advances in NHC–palladium catalysis for alkyne chemistry: versatile synthesis and applications

This review summarizes the recent developments in NHC–palladium catalysis for alkyne chemistry: versatile synthesis and applications.

Tandem Strecker/C(sp3)–H amination reactions for the construction of cyanide-functionalized imidazo[1,5-a]pyridines with NH4SCN as a cyanating agent

An I2O5-mediated multicomponent reaction that allows the single-step construction of cyano-functionalized imidazo[1,5-a]pyridines with molecular diversity was realized for the first time.

Silver-catalyzed decarboxylative radical relay difluoroalkylation–carbocyclization: convenient access to CF2-containing quinolinones

A practical Ag-catalyzed formal decarboxylation and radical difluoroalkylation–carbocyclization–hydrolysis route is established to construct a series of structurally diverse CF2-containing N-heterocycles.

Continuous-flow electrosynthesis of selenium-substituted iminoisobenzofuran via oxidative cyclization of olefinic amides and diselenides

A novel method for the continuous synthesis of selenated iminoisobenzofurans by cyclization of olefinic amides with diselenides through electrochemical oxidation under metal-free and oxidant-free conditions has been developed.