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

Radical-Triggered Bicyclization and Aryl Migration of 1,7-Diynes with Diphenyl Diselenide for the Synthesis of Selenopheno[3,4-c]quinolines

The translocation of an aryl group from selenium into carbon enabled by the cleavage of the C-Se bond is reported by using nitrogen atom-linked 1,7-diynes and diaryl diselenides as starting materials, leading to various selenophene derivatives in a regioselective manner. This method enables the construction of two C-Se bonds and two C-C bonds through sequential radical bicyclization and 1,2-aryl migration under metal-free conditions. Control experiments and mechanistic studies suggest that this reaction proceeds through the cleavage of the inert C(Ph)-Se bond, facilitating the aryl translocation process. This transformation enables the one-step conversion of simple diselenides into diverse selenopheno[3,4-c]quinolines via a radical-promoted process, holding significant potential for new seleniferous heterocycles.

Oxo-Sulfonylation of 1,7-Enynes via a Multicomponent Oxidative Radical Polar Crossover Approach

Diastereoselective synthesis of trans-3,4-difunctionalized tetrahydroquinoline and chromane derivatives via the oxo-sulfonylation of 1,7-enynes is demonstrated. The reaction involves a three-component oxidative radical polar crossover (ORPC) approach wherein a vinyl carbocation intermediate undergoes nucleophilic substitution to afford the corresponding keto functional group. Deprotection of the N-Ts group, gram-scale synthesis, and other synthetic applications were illustrated. Control experiments and mechanistic studies show that water acts as the nucleophile in this reaction.

Sustainable Synthesis through Catalyst-Free Photoinduced Cascaded Bond Formation

The beginning of photochemical reactions revolutionized synthetic chemistry through sustainable practices. This review explores cutting-edge developments in leveraging light-induced processes for generating cascaded C-C and C-hetero bonds without catalysts. Significantly, catalyst-free photoinduced methodologies have garnered considerable attention, especially in the creation of varied heterocyclic frameworks for drug design and the synthesis of natural products. The article delves into underlying mechanisms, addresses limitations, and evaluates various methodologies, emphasizing the potential of photocatalyst and transition metal-free photochemical reactions to enhance sustainability. Divided into two sections, it covers recent strides in C-C and C-heteroatom and multiple C-heteroatom bond formation reactions.

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.

Electrocatalytic Cascade Selenylation/Cyclization/Deamination of 2-Hydroxyaryl Enaminones: Synthesis of 3-Selenylated Chromones under Mild Conditions

Herein, we disclosed a highly efficient pathway toward 3-selenylated chromone derivatives via electrocatalytic cascade selenylation/cyclization/deamination of 2-hydroxyaryl enaminones with diselenides. This method showed mild conditions, easy operation, wide substrate scope, and good functional group tolerance. Furthermore, this electrosynthesis strategy was amendable to scale-up the reaction. Additionally, the preliminary experiments revealed that this reaction probably proceeded via a cation pathway instead of a radical pathway.

Visible photons as ideal reagents for the activation of coloured organic compounds

In recent decades, the traceless nature of visible photons has been exploited for the development of efficient synthetic strategies for the photoconversion of colourless compounds, namely, photocatalysis, chromophore activation, and the formation of an electron donor/acceptor (EDA) complex. However, the use of photoreactive coloured organic compounds is the optimal strategy to boost visible photons as ideal reagents in synthetic protocols. In view of such premises, the present review aims to provide its readership with a collection of recent photochemical strategies facilitated via direct light absorption by coloured molecules. The protocols have been classified and presented according to the nature of the intermediate/excited state achieved during the transformation.

Light-Driven Access to Selenium-Substituted Thiazole-2-imine Derivatives

The thiazole-2-imine derivatives with interesting pharmacological activities have attracted significant attention. However, previously reported synthesis strategies usually suffered from some drawbacks, such as the use of metals/additive and harsh reaction conditions. Herein, we developed a metal- and photoinitiator-free photocatalytic strategy for the synthesis of various selenium-substituted thiazole-2-imine derivatives for the first time. The reaction displayed mild reaction conditions, simple operation, a broad substrate scope (37 examples), and good to excellent yields.

Electrochemical Multicomponent Cascade Reaction for the Synthesis of Selenazol-2-amines with Elemental Selenium

The first example of an electrochemical multicomponent synthesis of selenium-containing compounds with inexpensive and abundant elemental selenium as the selenating reagent was developed. A variety of selenazol-2-amines were constructed in high yields with good functional group tolerance under metal-free and chemical oxidant-free conditions.

Strain-enabled radical spirocyclization cascades: rapid access to spirocyclobutyl lactones and - lactams

Spirocyclobutane derivatives have gained significant attention in drug discovery programs due to their broad spectrum of biological activities and clinical applications. Ring-strain in organic molecules is a powerful tool to promote reactivity by releasing strain energy, allowing the construction of complex molecules selectively and efficiently. Herein, we report the first strain-enabled radical spirocyclization cascades for the synthesis of functionalized spirocyclobutyl lactones and - lactams, which are finding increasing applications in medicinal chemistry. The reaction of interelement compounds with bicyclobutane (BCB) allyl esters and - amides proceeds with high chemoselectivity under simple, catalyst-free conditions using blue light irradiation. The reaction has been successfully extended to synthesize bis-spirocycles. To introduce a more diverse set of functional groups, we have developed a dual photoredox/nickel catalytic system capable of mediating the carbosulfonylation of BCB allyl amides. The reaction shows broad applicability across various (hetero)aryl halides, aryl sulfinates, and BCB allyl amides, operates under mild conditions and demonstrates excellent functional group compatibility. The functional groups introduced during the cascade reactions served as versatile handles for further synthetic elaboration.

Selectfluor-Mediated Electrophilic Annulation of 2-Alkynyl Biaryls with Diorganyl Diselenides

A general and efficient method for the synthesis of various selanyl phenanthrenes/polycyclic heteroaromatics through the electrophilic annulation of 2-alkynyl biaryls with diorganyl diselenides under metal-free and mild conditions was established. The sulfanyl phenanthrene was also obtained in moderate yields.

Photoinduced Radical Cyclization of 2-Alkynylthioanisoles with Disulfides without an External Photocatalyst

An efficient strategy for the synthesis of 3-arylthiobenzo[b]thiophenes via a photodriven radical cyclization of 2-alkynylthioanisoles with disulfide was developed. The reaction proceeded smoothly under visible-light irradiation without any external photocatalyst and generated the desired products in high yields with good functional group tolerance.