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We described here a simple and metal‐free protocol to synthesize [1,2,3]triazolo[1,5‐a]quinoline 3‐carboxamides through a two‐step synthetic strategy, in which the first step uses organocatalysis (10 mol % of diethylamine or 1,8‐diazabicyclo[5.4.0]undec‐7‐ene, while the second step involves the use of inorganic base (1.2 or 0.1 equiv. of potassium hydroxide). These reactions were performed between β‐keto amides and o‐carbonyl phenylazides in dimethylsulfoxide as solvent at 70 °C for 2 h. The synthetic protocol is ample, which thirteen examples of secondary [1,2,3]triazolo[1,5‐a]quinoline 3‐carboxamides were synthesized ranging from good to excellent yields (63‐96 %), and six different tertiary [1,2,3]triazolo[1,5‐a]quinolines 3‐carboxamides were obtained ranging from moderate to good yields (48–76 %). [ABSTRACT FROM AUTHOR]

We report a protocol for the synthesis of new dialkyl(1‐(organolthio)naphthalen‐2‐yl)phosphates and derivatives via a dehydrogenative phosphorylation reaction between functionalized naphthols and H‐phosphonates. Diphenyl ditelluride was employed as an organocatalyst and sonochemistry as an alternative energy source. The reaction conditions were defined through a factorial design approach, and the best condition provided the synthesis of dialkyl(1‐(organolthio)naphthalen‐2‐yl)phosphates in yields that varied from 51–98 % under ultrasound irradiation after 2 h of sonication. The synthetic protocol was also effective for phenol and thiophenol starting materials. All products were characterized by state‐of‐the‐art spectroscopic and spectrometric techniques. [ABSTRACT FROM AUTHOR]

A mild and regioselective approach to the direct selenylation of 4‐(N‐substituted‐amino)‐2H‐chromen‐2‐ones employing Selectfluor® and diorganyl diselenides has been developed. The reactions were carried out under metal‐free conditions, without the need for special devices, and using NaHCO3 as a mild base at room temperature under air. This approach has been suitable for a wide substrate scope affording the 3‐selenyl‐4‐(N‐substituted‐amino)‐2H‐chromen‐2‐ones in good to excellent yields. [ABSTRACT FROM AUTHOR]

A metal‐ and catalyst‐free photo‐promoted cyclization of properly substituted vinyl selenides was developed using UVA irradiation. A total of eighteen new C3‐unsubstituted 2‐selanyl benzochalcogenophenes (benzofurans, benzothiophenes and benzoselenophenes) were prepared in 30–86% yield after irradiation with UVA at room temperature. The usefulness of the title compounds was demonstrated in the easy functionalization of the remaining free C−H bond of the benzochalcogenophenes to form new C−Se and C−Br bonds by simple procedures. Furthermore, the reaction can be performed under natural sunlight irradiation and the solvent is easily reused further in several subsequent runs. [ABSTRACT FROM AUTHOR]

The ability of chalcogenium salts to transfer an electrophilic moiety to a given nucleophile is well known. However, up to date, these reagents have been used in stoichiometric quantities, producing a substantial amount of waste as byproducts of the reaction. In this report, we disclose further investigation of selenonium salts as S‐adenosyl‐L‐methionine (SAM) surrogates for the alkylation of nucleophiles in aqueous solutions. Most importantly, we were able to convert the stoichiometric process to a catalytic system employing as little as 10 mol % of selenides to accelerate the reaction between benzyl bromide and other alkylating agents with sodium cyanide in water. Probe experiments including 77Se NMR and HRMS of the reaction mixture have unequivocally shown the presence of the selenonium salt in the reaction mixture. [ABSTRACT FROM AUTHOR]

We describe herein an alternative method for the synthesis of 2‐aryl‐(3‐organochalcogenyl)thieno[2,3‐b]pyridines through the electrophilic cyclization of 3‐(arylethynyl)‐2‐(alkylthio)pyridines promoted by electrophilic species of organochalcogen compounds. These species were generated in situ by the oxidative cleavage of chalcogen‐chalcogen (Se, Te) bond of diorganyl dichalcogenides using Oxone® in ethanol as solvent in an open‐flask at 78 °C. The protocol allowed the synthesis of highly substituted thieno[2,3‐b]pyridines starting from several diorganyl dichalcogenides and 3‐(arylethynyl)‐2‐(alkylthio)pyridines, obtaining 21 new compounds in good to excellent yields (70–99%). Still, the method showed good efficiency on the gram‐scale synthesis. In addition, several synthetic transformations such as oxidation, selenylation and hydrogenation reactions were demonstrated. [ABSTRACT FROM AUTHOR]

In this work, a one‐pot sequential organocatalytic method for the synthesis of fused [1,2,3]triazolo[1,5‐a]quinolines through successive cyclization and condensation is presented. In this synthetic strategy, the intermolecular [3+2]‐cycloaddition occurs between 1,3‐dicarbonyl compounds and o‐carbonyl‐substituted phenylazide compounds, for the formation of the 1,2,3‐triazole intermediates. Subsequently, an intramolecular condensation reaction generates the fused quinoline ring by the new C−C bond formation, giving the products in yields ranging from moderate to excellent. All the reactions were performed using 20 mol% of 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU) as catalyst in the presence of DMSO as solvent at 120 °C for 24 h and tolerate a range of 1,3‐dicarbonyl compounds, such as β‐keto esters and 1,3‐diketones, and o‐formyl, o‐acetyl or o‐benzoyl substituted phenylazide compounds. [ABSTRACT FROM AUTHOR]

Herein, we described a simple and efficient protocol for the synthesis of α‐hydroxyphosphonates containing 1,2,3‐triazole moiety in their structures under mild conditions. This approach was performed by Abramov reaction in a solvent‐free system, using Na2CO3 as catalyst at 70 °C, which provided the desired products from moderate to excellent yields. The substrate scope was effective for different organic functions, such as ester, ketone, and amide. The synthetic route is modulated by the presence of a bulky group at the hydrophosphoryl reagent, avoiding steric hindrance, since the Abramov reaction can be approached before the Click‐Chemistry protocol. The synthesis can also be carried out in a one‐pot method, minimizing costs, and without side reactions. Additionally, the chiral discrimination of the synthesized products was easily accessed by 1H and 31P nuclear magnetic resonance experiments, using a chiral solvating agent. [ABSTRACT FROM AUTHOR]

We describe here for the first time the synthesis of isochromenones fused to selenophenes. 5H‐Selenopheno[3,2‐c]isochromen‐5‐ones were obtained through a double intramolecular cyclization of methyl 2‐(organyl‐1,3‐diynyl)benzoate promoted by electrophilic species of selenium generated in situ by the reaction of dialkyl diselenides with Oxone®, using ethanol as solvent. The reactions were conducted satisfactorily under mild conditions, using a range of 1,3‐diynes and dialkyl diselenides as substrates. A total of sixteen unprecedent 5H‐selenopheno[3,2‐c]isochromen‐5‐ones were selectively obtained in moderate to good yields (40–86%) under reflux in an open flask and in short reaction times (1.0–2.5 h). [ABSTRACT FROM AUTHOR]

We describe herein our results on the synthesis of bisarylselanylbenzo‐2,1,3‐selenadiazoles through double cross‐coupling reaction. The named compounds were obtained in moderate to good yields by reactions of a range of diaryl diselenides with the 4,7‐dibromobenzo[c][1,2,5]selenadiazole using 20 mol‐% of CuO nanoparticles as a catalyst. In addition, the obtained compounds were investigated regarding their photophysical properties in solution and singlet oxygen generation. Bisarylselanylbenzo‐2,1,3‐selenadiazoles presents strong absorption bands at UV region and red emission properties, depending on the substituent. Geometrical, photophysical and electronic properties of the compounds are characterized with density functional theory calculations. In all derivatives are observed the oxidation process of Se atom, using electrochemical analysis. Also, the quantum yields of photosensitized 1O2 production of the synthesized compounds were slightly lower than the standard, but still displays good ability to generate singlet oxygen species. The ability to generate 1O2 of benzo‐2,1,3‐selenadiazole derivatives after being exposed to light and oxygen allowed us to envisage them as a potential application in photodynamic therapy. The synthesis, photophysics, electrochemical and singlet‐oxygen‐generation properties of bis‐arylselanyl‐benzo‐2,1,3‐selenadiazoles are described. These compounds were obtained in moderate to good yields. The ability to generate 1O2 of benzo‐2,1,3‐selenadiazole derivatives after exposure to light and oxygen allowed us to envisage them as a potential application in photodynamic therapy. [ABSTRACT FROM AUTHOR]

This paper describes an alternative method for the synthesis of 3-organoselanylbenzo[b]furans through the intra-molecular cyclization of 2-alkynylphenols promoted by copper iodide and diorganyl diselenides. The cyclization reactions were carried out at room temperature in the absence of base and under air (open flask). This synthetic approach proved to be efficient with both diorganyl diselenides and 2-alkynylphenols bearing electron-neutral, electron-donating, and electron-withdrawing substituents. 2-Phenyl-3-phenylselanylbenzo[b]furan was used as a synthetic precursor in organochalcogen--lithium exchange and bromination reactions, allowing the synthesis of functionalized benzo[b]furans in good yields. [ABSTRACT FROM AUTHOR]

Abstract: We describe a selective and direct method to synthesize a wide variety of 5‐selanyl‐imidazo[2,1‐b]thiazoles by copper(I)–catalyzed reaction of imidazo[2,1‐b]thiazoles with diorganyl diselenides. The reactions were carried out in DMSO at 90 °C in air. The methodology was tolerant to differently substituted diorganyl diselenides containing electron‐deficient, electron‐rich, and bulky groups. Still, various imidazo[2,1‐b]thiazoles were used and furnishing the expected products in good to excellent yields. All the products were selectively coupled at 5‐position of the imidazo[2,1‐b]thiazole and no regioisomers were detected. [ABSTRACT FROM AUTHOR]

The retro-Favorskii reaction is an excellent way to achieve terminal alkynes. Methodologies that connect the synthesis of terminal alkynes and organochalcogen motifs are important for the construction of novel compounds. Fourteen new terminal alkynes containing either Csp−S or Csp−Se bonds were selectively prepared through the retro-Favorskii reaction from the respective carbinol precursors. It was discovered that terminal chalcogen alkynes were stable for weeks if stored as a solution in hexanes. [ABSTRACT FROM AUTHOR]

We describe our results on the synthesis of fused 1,2,3-triazolo-1,3,6-triazonines through a copper-catalyzed multicomponent reaction. The products were obtained in moderate to excellent yields by the reaction of 2-azidobenzaldehydes, substituted diaminobenzenes and a range of terminal alkynes in the presence of a catalytic amount of copper iodide, with Et3N as base, in DMSO at 100 °C. This method proved to be efficient for the combinatorial synthesis of new medium-sized N-heterocyclic rings with potential applications in biological studies. [ABSTRACT FROM AUTHOR]

A protocol for the stereocontrolled synthesis of (E)- and (Z)-β,γ-unsaturated esters and amides is reported. [ABSTRACT FROM AUTHOR]