Study on the Application of Photoelectric Technology in the Synthesis of Selenium-Containing Heterocycles

Visible-light-induced three-component reactions of α-diazoesters, quinazolinones and cyclic ethers toward quinazoline-based hybrids

An effective approach for the construction of 4-short-chain ether attached carbonyl group-substituted quinazolines was developed. Visible-light-induced three-component reactions of α-diazoesters, quinazolinones, and cyclic ethers, with a broad substrate scope and excellent functional group tolerance, under extremely mild conditions without the need for any additional additives and catalysts, selectively led to quinazoline-based hybrids in good to excellent yields. The synthesized hybrids, which are a conglomeration of a quinazoline, a short-chain ether, and a carbonyl group in one molecular skeleton, have potential for application in the development of new drugs or drug candidates.

Selenium Modification of Natural Products and Its Research Progress

The selenization of natural products refers to the chemical modification method of artificially introducing selenium atoms into natural products to interact with the functional groups in the target molecule to form selenides. Nowadays, even though scientists in fields involving organic selenium compounds have achieved numerous results due to their continuous investment, few comprehensive and systematic summaries relating to their research results can be found. The present paper summarizes the selenization modification methods of several kinds of important natural products, such as polysaccharides, proteins/polypeptides, polyphenols, lipids, and cyclic compounds, as well as the basic principles or mechanisms of the selenizing methods. On this basis, this paper explored the future development trend of the research field relating to selenized natural products, and it is hoped to provide some suggestions for directional selenization modification and the application of natural active ingredients.

Photo- or Electrochemical Cyclization of Dienes with Diselenides to Access Seleno-Benzo[b]azepines

A cascade selenylation/cyclization of dienes with diselenides has been realized under visible-light irradiation or electrolysis conditions. Employing O₂ or electricity as a "green" oxidant, this protocol provides a green and efficient method for an array of biologically important seleno-benzo[b]azepine derivatives in moderate to good yields. The direct sunlight irradiation and gram-scale reaction render the approach practical and attractive.

Electro-Oxidative C3-Selenylation of Pyrido[1,2-a]pyrimidin-4-ones

In this work, we achieved a C3-selenylation of pyrido[1,2-a]pyrimidin-4-ones using an electrochemically driven external oxidant-free strategy. Various structurally diverse seleno-substituted N-heterocycles were obtained in moderate to excellent yields. Through radical trapping experiments, GC-MS analysis and cyclic voltammetry study, a plausible mechanism for this selenylation was proposed.

Synthesis and Application Dichalcogenides as Radical Reagents with Photochemical Technology

Dichalcogenides (disulfides and diselenides), as reactants for organic transformations, are important and widely used because of their potential to react with nucleophiles, electrophilic reagents, and radical precursors. In recent years, in combination with photochemical technology, the application of dichalcogenides as stable radical reagents has opened up a new route to the synthesis of various sulfur- and selenium-containing compounds. In this paper, synthetic strategies for disulfides and diselenides and their applications with photochemical technology are reviewed: (i) Cyclization of dichalcogenides with alkenes and alkynes; (ii) direct selenylation/sulfuration of C-H/C-C/C-N bonds; (iii) visible-light-enabled seleno- and sulfur-bifunctionalization of alkenes/alkynes; and (iv) Direct construction of the C(sp)-S bond. In addition, the scopes, limitations, and mechanisms of some reactions are also described.

Photosynthesis of 3-Alkylated Coumarins from Carboxylic Acids Catalyzed by a Na2S-Based Electron Donor-Acceptor Complex

A simple and practical electron donor-acceptor (EDA) strategy to synthesize various 3-alkylated coumarins from easily available coumarins and naturally abundant carboxylic acids under photocatalyst-, oxidant-, and additive-free and mild conditions is reported. Using Na₂S as the catalytic electron donor, a series of primary, secondary, and tertiary carbon radicals can be efficiently generated, and the EDA complex can be regenerated without an alkaline additive.

Photoinduced Construction of Thieno[3,4-c]quinolin-4(5H)-ones/Selenopheno[3,4-c]quinolin-4(5H)-ones Using Diphenyl Disulfide or Diphenyl Diselenide as Sulfur or Selenium Sources

A photocatalytic synthesis of thieno[3,4-c]quinolin-4(5H)-ones/selenopheno[3,4-c]quinolin-4(5H)-ones using diphenyl disulfide or diphenyl diselenide as sulfur or selenium sources was developed. Two C-S/Se bonds and one C-C bond were constructed simultaneously without transition metals and other additives.

Copper(I)-Catalyzed Three-Component Selenosulfonation of Maleimides with Sulfonyl Hydrazides and Diselenides via Radical Relay

By employing Cu(CH₃CN)₄PF₆ as the catalyst and tert-butyl hydroperoxide as the oxidant, we realized a three-component radical selenosulfonation of substituted maleimides, sulfonyl hydrazides, and diphenyl diselenides, providing a series of 3,4-selenosulfonylated succinimides in moderate to good yields. This reaction features broad substrate scopes, high functional-group tolerability, and feasibility of gram-scale synthesis, enabling one-step construction of C-SO₂ and C-Se bonds under mild reaction conditions. Preliminary mechanistic studies support the free-radical-induced pathway.

Visible-Light-Initiated Multicomponent Reactions of α-Diazoesters to Access Organophosphorus Compounds

A simple visible-light-initiated strategy has been established for the construction of organophosphorus compounds via aerobic multicomponent reaction of α-diazoesters, cyclic ethers, and P(O)H compounds under air. A number of phosphonates and phosphinates could be efficiently isolated in moderate to good yields without the use of photosensitizers and metal reagents. This multicomponent reaction has advantages of mild condition, simple operation, eco-friendly energy, good functional-group tolerance, and gram-scale synthesis.

Synthesis of Selenyl-Substituted Quinoline Derivatives via Substrate-Controlled Three-Component Domino Reactions

A simple and efficient method for the preparation of selenyl-substituted quinoline derivatives through a CSp3-H selenylation of in situ-generated 3-acetyl quinoline has been developed. This protocol is easy to handle, scalable, and good functional group tolerant, providing a rapid method to 3-selenoacetyl quinoline and 3-diselenoacetyl quinoline derivatives.

Radical annulation of a designed diene system: access to nitro-benzo[b]azepines

Herein, we describe a novel O₂N˙-triggered ordered addition 7-endo cyclization reaction with excellent chemo- and regioselectivity. With such a strategy, structurally diverse nitro-benzo[b]azepines were prepared with 28 examples. Large-scale operation and handy N-Ts and N-Cbz deprotection reveal the promising utility of this methodology. Mechanistic studies suggest that the reaction proceeds through a radical pathway.

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.

Visible-Light-Promoted Denitrogenative Ortho-selenylation Reaction of benzotriazinones: Synthesis of ortho-selenylated Benzamides, Ebselen Analogs

A visible-light-promoted regioselective denitrogenative cross-coupling between benzotriazinones and selenosulfonates is reported. This protocol allows for the convenient synthesis of ortho-selenylated benzamides in good yields from readily available starting materials under...

Visible Light-Promoted Selenylative Spirocyclization of Biaryl Ynones toward the Formation of Selenated Spiro[5.5]trienones

A visible-light induced dearomative cascade cyclization of biaryl ynones with diselenides under photocatalyst and external additive-free conditions has been explored, giving a series of selenated spiro[5.5]trienones in moderate to good...

Visible-light-mediated multi-component carbene transfer reactions of α-diazoesters to construct multisubstituted pyrazoles and 1,3-dicarbonyl derivatives

A visible-light-promoted strategy has been developed for the assembly of multisubstituted pyrazoles and 1,3-dicarbonyl derivatives via a multi-component carbene transfer reaction of α-diazoesters.

Electrochemical regioselective C-H selenylation of 2H-indazole derivatives

Selenium-substituted heteroarenes are biologically active compounds and useful building blocks. In this study, we have developed a metal- and oxidant-free, environmentally friendly protocol for the regioselective selenylation of 2H-indazole derivatives by an electrochemical strategy. A number of selenylated 2H-indazoles with a wide range of functional groups have been synthesized in moderate to good yields under mild and environment-friendly reaction conditions.