Copper/DTBP-Promoted Oxyselenation of Propargylic Amines with Diselenides and CO2: Synthesis of Selenyl 2-Oxazolidinones

DABCO-Catalyzed Synthesis of Thiazolidine-2-thiones: System Development and Mechanistic Insights

A base-catalyzed protocol is reported for the construction of 1,3-thiazolidine-2-thione scaffolds bearing quaternary carbon centers from carbon disulfide and α-tertiary propargylamines. The reaction proceeds using low catalyst loading, under ambient temperatures, and in the absence of solvent. Various α-tertiary propargylamines have been employed, affording a series of previously unreported thiazolidine-2-thione compounds and avoiding purification via column chromatography in certain cases. We also describe a one-pot strategy for the synthesis of the same products through a KA2 coupling-CS2 incorporation approach. The reaction mechanism and substituent-dependent catalytic behavior were studied through a combination of detailed experimental and computational studies.

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.

Novel and highly efficient transformation of carbon dioxide into 2-oxazolidinones over Al-MCM-41 mesoporous-supported ionic liquids

A type of Al-MCM-41 supported dual imidazolium ionic liquids were constructed and efficiently used as catalysts for the synthesis of 2-oxazolidinones from epoxides, amines, and CO2. The influence of the different catalysts and reaction parameters on the catalytic behaviours was investigated. Al-MCM-41@ILTiCl5 was identified as the most excellent catalyst because it could efficiently promote the three-component cycloaddition of CO2, epoxide, and amines to form the corresponding 2-oxazolidinones in high to excellent yields (84∼96%) with excellent selectivities (98∼99.7%). In addition, the recovery and reuse performances of Al-MCM-41@ILTiCl5 were examined. The catalyst could be recovered by simple filtration and reused six times without a change in the catalytic activity. Green reaction conditions, operational simplicity, feasibility, and sustainability of the functionalized catalyst are the main highlights of the present protocol.

Visible-light-induced bifunctionalisation of (homo)propargylic amines with CO2 and arylsulfinates

An unprecedented carboxylative sulfonylation of (homo)propargyl amines with CO2 and sodium arylsulfinates under visible light irradiation has been developed with high efficiency. This ruthenium-catalysed photochemical protocol offers broad substrate scope giving 2-oxazolidinones and 2-oxazinones bearing alkyl sulfones in good yields under ambient reaction conditions. An in situ double bond isomerisation occurs in tandem. A mechanistic rationale for these radical-initiated carboxylative cyclisations involving sulfinyl radicals is presented, supported by control and quenching experiments.

Chemical insights into the synthetic chemistry of five-membered saturated heterocycles-a transition metal-catalyzed approach

Drug design and delivery is primarily based on the hunt for new potent drug candidates and novel synthetic techniques. Recently, saturated heterocycles have gained enormous attention in medicinal chemistry as evidenced by the medicinal drugs listed in the FDA Orange Book. Therefore, the demand for novel saturated heterocyclic syntheses has increased tremendously. Transition metal (TM)-catalyzed reactions have remained the prime priority in heterocyclic syntheses for the last three decades. Nowadays, TM catalysis is well adorned by combining it with other techniques such as bio- and/or enzyme-catalyzed reactions, organocatalysis, or using two different metals in a single catalysis. This review highlights the recent developments of the transition metal-catalyzed synthesis of five-membered saturated heterocycles.

Novel MCM-41 Supported Dicationic Imidazolium Ionic Liquids Catalyzed Greener and Efficient Regioselective Synthesis of 2-Oxazolidinones from Aziridines and Carbon Dioxide

A type of MCM-41 supported dicationic imidazolium ionic liquid nanocatalyst has been synthesized and found to be competent for the synthesis of 2-oxazolidinones through the sustainable chemical conversion of CO2 with aziridines. It was shown that the highest efficiency was achieved in the cycloaddition of a series of aziridines and CO2 in the presence of a catalytic amount of the solid catalyst MCM-41@ILLaCl4 under mild conditions. Merits of this meticulously designed protocol are the use of a novel supported ionic liquid catalyst, the easy work-up process, good to excellent yields, a short reaction time, and purification without column chromatography. Overall, the present protocol of synthesizing 2-oxazolidinones under cocatalyst- and solvent-free conditions using MCM-41@ILLaCl4 is promising for industrial applications.

Nitrogen-Rich Porous Organic Polymers with Supported Ag Nanoparticles for Efficient CO2 Conversion

As CO₂ emissions increase and the global climate deteriorates, converting CO₂ into valuable chemicals has become a topic of wide concern. The development of multifunctional catalysts for efficient CO₂ conversion remains a major challenge. Herein, two porous organic polymers (NPOPs) functionalized with covalent triazine and triazole N-heterocycles are synthesized through the copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) reaction. The NPOPs have an abundant microporous content and high specific surface area, which confer them excellent CO₂ affinities with a CO₂ adsorption capacity of 84.0 mg g^-1 and 63.7 mg g^-1, respectively, at 273 K and 0.1 MPa. After wet impregnation and in situ reductions, Ag nanoparticles were supported in the NPOPs to obtain Ag@NPOPs with high dispersion and small particle size. The Ag@NPOPs were applied to high-value conversion reactions of CO₂ with propargylic amines and terminal alkynes under mild reaction conditions. The carboxylative cyclization transformation of propargylic amine into 2-oxazolidinone and the carboxylation transformation of terminal alkynes into phenylpropiolic acid had the highest TOF values of 1125.1 and 90.9 h^-1, respectively. The Ag@NPOP-1 was recycled and used five times without any significant decrease in catalytic activity, showing excellent catalytic stability and durability.

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.

Diorganyl Diselenides and Iron(III) Chloride Drive the Regio- and Stereoselectivity in the Selenation of Ynamides

We report here our results on the application of ynamides as substrates in the reactions with diorganyl dichalcogenides and iron(III) chloride to give selectively three different types of compounds: E-α-chloro-β-(organoselenyl)enamides, 4-(organochalcogenyl)oxazolones, and vinyl tosylates. The results reveal that the selectivity in the formation of products was obtained by controlling the functional groups directly bonded to the nitrogen atom of the ynamides. Thus, α-chloro-β-(organoselenyl) enamide derivatives were exclusively obtained when the TsN- and MsN-ynamides were treated with a mixture of diorganyl diselenides (1.0 equiv) and FeCl₃ (3.0 equiv) in dichloroethane (DCE, 3 mL), at room temperature. The 4-(organochalcogenyl)oxazolones were selectively obtained with ynamides having an ester group, directly bonded to the nitrogen atom, upon treatment with a solution of FeCl₃ (1.5 equiv) and diorganyl dichalcogenides (1.0 equiv) in dichloromethane (3 mL) at room temperature. Finally, vinyl tosylates were obtained from ynamides having an ester group, directly bonded to the nitrogen atom, by reaction with p-toluenesulfonic acid. We also studied the application of the prepared compounds as substrates for Suzuki and Sonogashira cross-coupling reactions.

One-Pot CuI/DBU-Catalyzed Carboxylative Cyclization toward Oxazolidinones Using Recyclable Molecular Sieves as Efficient Promoters for Fixation of CO2 in Water Medium

An efficient one-pot synthesis of oxazolidinones was developed through CuI/DBU/MS joint system-catalyzed carboxylative cyclization of arylacetylene, arylaldehyde, and arylamine in water medium under a 1 atm carbon dioxide (CO₂) atmosphere. The 4 Å molecular sieves (MSs) were added to improve CO₂ capture and facilitate carboxylation to give the products in high yields. The CuI/DBU/MS system is robust and highly effective for the reactions with different substrates, and some target products were obtained in an excellent yield of ∼96%, with no side products in the final step.