Cyclodextrin Polymer-Loaded Micro-Ceramic Balls for Solid-Phase Extraction of Triazole Pesticides from Water.

A citric acid cross-linked ß-cyclodextrin (ß-CD) polymer was synthesized and loaded on micro-ceramic balls to fabricate the solid-phase adsorbents (P-MCB) for adsorption and extraction of triazole pesticides from water. The stability of ß-CD polymer and P-MCB was investigated in solutions with different pH values at different temperatures. The adsorption properties and the influence of kinetics, sorbent amount, pesticide concentration, and temperature on the adsorption capacity were evaluated. The results showed P-MCB had favorable adsorption of 15.98 mg/g flutriafol in 3.5 h. The equilibrium data followed the Freundlich equation, and the adsorption of flutriafol and diniconazole followed the second-order kinetics. The recovery rate of P-MCB for triazole pesticides in water was satisfactory, and the recovery rate was still 80.1%, even at the 10th cycle. The P-MCB had good stability, with a degradation rate of 0.2% ± 0.08 within 10 days, which could ensure extraction and recycling.

Palladium-Catalyzed Ring-Opening Reaction of Cyclopropenones with Vinyl Epoxides.

We report herein the Pd-catalyzed selective ring-opening reaction of cyclopropenones with vinyl epoxides. By using a commercially available Pd2(dba)3·CHCl3-BINAP catalyst, a wide range of conjugated alkadienyl carboxylates could be accessed in good yield and excellent regioselectivity. The new application of zwitterionic π-allyl palladium intermediates has been demonstrated in organic synthesis.

P/N-Heteroleptic Cu(I)-Photosensitizer-Catalyzed [3 + 2] Regiospecific Annulation of Aminocyclopropanes and Functionalized Alkynes.

We report here a regiospecific [3 + 2] annulation between aminocyclopropanes and various functionalized alkynes enabled by a P/N-heteroleptic Cu(I) photosensitizer under photoredox catalysis conditions. Thus, a divergent construction of 3-aminocyclopentene derivatives including methylsulfonyl-, arylsulfonyl-, chloro-, ester-, and trifluoromethyl-functionalized aminocyclopentenes could be achieved with advantages of high regioselectivity, broad substrate compatibility, and mild and environmentally benign reaction conditions.

Unexpected synthesis, delayed emission and solid-state acidochromism of novel 2,7-naphthyridine derivatives obtained from 2-(3,5-diaryl-4H-pyran-4-ylidene)malononitrile.

Two novel 2,7-naphthyridine derivatives are unexpectedly synthesized by the reaction of 2-(3,5-diaryl-4H-pyran-4-ylidene)malononitrile and benzylamine, and are achieved through different ring-closing mechanisms. These two derivatives with twisted molecular conformations display phosphorescence, thermally activated delayed fluorescence, and high contrast solid-state acidochromism due to special chemical structures.

Metal-Free Synthesis of Aryl Selenocyanates and Selenaheterocycles with Elemental Selenium.

This work reports a green method for the synthesis of aryl selenocyanates via a three-component reaction of arylboronic acids, Se powder, and trimethylsilyl cyanide (TMSCN) under metal-free and additive-free conditions. Remarkably, TMSCN acts as not only the substrate, but also the catalyst. Various selenaheterocycles can be also accessed with a catalytic amount of TMSCN.

α-Selective C(sp3)-H Thio/Selenocyanation of Ketones with Elemental Chalcogen.

A facile method is disclosed for the synthesis of α-thio/selenocyanato ketones through regioselective C-H thio/selenocyanation of ketones. The advantages include the use of easily available starting materials, high efficiency, simple operation, and easy scale-up. Control experiments provide evidence that the reaction proceeded via a radical way, while kinetic isotope effect experiments reveal that the cleavage of the C-H bond serves as the rate-limiting step.

Palladium-catalyzed coupling reaction of 2-iodobiphenyls with alkenyl bromides for the construction of 9-(diorganomethylidene)fluorenes.

An atom economical protocol for the construction of 9-(diorganomethylidene)fluorenes through palladium-catalyzed coupling reactions of 2-iodobiphenyls with alkenyl bromides has been reported. The reaction proceeds through the C-H activation/oxidative addition/reduction elimination/intramolecular Heck coupling reaction to afford a series of 9-(diorganomethylidene)fluorenes with good yields. Control experiments demonstrate that a five-membered palladacycle acts as a key intermediate and ß-H elimination serves as the rate-limiting step.

Tunable Phosphorescence/Fluorescence Dual Emissions of Organic Isoquinoline-Benzophenone Doped Systems by Alkoxy Engineering.

Dual/multi-component organic doped systems with room-temperature phosphorescence (RTP) properties have been developed. However, the unknown luminescence mechanism still greatly limits the development of the doped materials. Herein, a new doped system exhibiting phosphorescence/fluorescence dual emission (Φphos =4-24 % and τphos =101-343 ms) is successfully constructed through prediction and design. A series of isoquinoline derivatives with different alkoxy chains were selected as the guests. Benzophenone was chosen as the host owing to the characteristics of low melting point and good crystallinity. The alkoxy chain lengths of the guests are first reported to be used to control the fluorescence and phosphorescence intensities of the doped materials, which results in different prompt emission colors. Additionally, the doped ratio of the guest and host can also control the luminous intensities of the materials. In particular, the doped materials still exhibit phosphorescent properties even if the ratio of the guest/host is as low as 1:100 000.

Ag2O-promoted ring-opening reactions of cyclopropenones with oximes.

Ag2O-promoted ring-opening reactions of cyclopropenones with oximes is disclosed in this work, providing a direct route to 1,3-oxazinones. This method highlights a new reactivity of cyclopropenones which undergo 1,4-addition with oximes followed by ß-carbon elimination to in situ generate a α-carbonyl ketene intermediate.

Synthesis of cyclic gem-dinitro compounds via radical nitration of 1,6-diynes with Fe(NO3)3·9H2O.

Cyclic gem-dinitro compounds were obtained via nitration of 1,6-diynes using Fe(NO3)3·9H2O as the nitrating agent. The reaction proceeds at room temperature using a cheap nitrating agent. A number of gem-dinitro cyclic compounds were obtained in moderate to good yields. The reaction offers an easy and convenient protocol to prepare gem-dinitro compounds, which are not easily obtained via the known procedures.

Base-Controlled Three Component Reactions of Amines, Elemental Sulfur, and Styrenes: Synthesis of Thioamides under Metal-Free Conditions.

Three component reactions of olefins, amines, and sulfur were studied. Thioamidation of styrenes is base-controlled, and 2-phenylethanethioamides and benzothioamides were obtained selectively in the presence of two different bases. This protocol offers a simple and efficient procedure for the synthesis of thioamides.

Palladium-Catalyzed Sequential Heteroarylation/Acylation Reactions of Iodobenzenes: Synthesis of Functionalized Benzo[ d]oxazoles.

We report an efficient palladium-catalyzed approach to the synthesis of benzoxazole derivatives via sequential heteroarylation/acylation reaction of iodobenzenes. Three readily available starting materials, iodobenzenes, anhydrides, and benzoxazoles, were smoothly coupled to form new C-C bonds at the ortho and ipso positions of the iodobenzenes to afford 2-heteroaryl-3-acylbenzene derivatives in good yields.

Copper(I)-Catalyzed N-O Bond Formation through Vinyl Nitrene Mediated Pathway under Mild Conditions.

Copper(I)-catalyzed N-O bond formation reactions through vinyl nitrene-mediated pathway were described. The reactions of N-alkoxylbenzamides and 2 H-azirines afforded α-amino oxime ethers in good to excellent yields at room temperature, which involved the cleavage of C-N and N-O bonds and the construction of new N-O and C-N bonds. It offers an efficient, regio- and stereoselective synthetic route for α-amino oxime ethers.

The Development of a Palladium-Catalyzed Tandem Addition/Cyclization for the Construction of Indole Skeletons.

A palladium-catalyzed tandem addition/cyclization of 2-(2-aminoaryl)acetonitriles with arylboronic acids has been developed for the first time, achieving a new strategy for direct construction of indole skeletons. This system shows good functional group tolerance and remarkable chemoselectivity. In particular, the halogen (e.g., bromo and iodo) substituents are amenable to further synthetic elaborations thereby broadening the diversity of the products. Preliminary mechanistic experiments indicate that this transformation involves sequential nucleophilic addition followed by an intramolecular cyclization.

Copper-Catalyzed Three-Component Coupling Reaction of Azoles, Se Powder, and Aryl Iodides.

A copper-catalyzed three-component coupling reaction of azoles, Se powder, and aryl iodide is described for the first time. This transformation provides a straightforward and facile pathway to synthesis 2-arylselanyl-azoles via a copper-catalyzed double C-Se bonds formation process. This reaction is attractive and practical since the cheap copper catalyst is employed and it does not require ligands, proceeds in generally good yields, and has a broad range of functional groups tolerance.

Copper-catalyzed ipso-selenation of aromatic carboxylic acids.

The copper-catalyzed decarboxylative selenation of aromatic carboxylic acids with diselenide is reported. This transformation tolerated a diverse set of functional groups on the substrates, including pentafluorobenzoic acid and heteroaromatic acids, delivering diaryl and methyl aryl selenides in good to excellent yields. Mechanistic studies indicated that the copper catalyst is essential in the activation of the Se-Se bond and the decarboxylation of aromatic acids. The utility of the products has been demonstrated in the facile synthesis of 10H-phenoselenazine and 11-methyldibenzo-(b,f)-1,4-selenazepine.

Copper-catalyzed C-O bond cleavage and cyclization: synthesis of indazolo[3,2-b]quinazolinones.

The first example of a copper-catalyzed halogen-free protocol to construct indazolo[3,2-b]quinazolinones was developed through sequential inert C-O bond cleavage followed by intramolecular C-N bond formation. This protocol represents an efficient synthetic tool for accessing a more diverse range of functionalized indazolo[3,2-b]quinazolinones. The structure of the newly synthesized indazolo[3,2-b]quinazolinones was unambiguously confirmed by X-ray crystal diffraction analysis.

Copper-Catalyzed Three-Component Reaction for Regioselective Aryl- and Heteroarylselenation of Indoles using Selenium Powder.

A new and efficient copper-catalyzed C3 aryl- and heteroarylselenation of indoles employing selenium powder has been developed. The advantages of this chemistry involve the use of cheap selenating reagents, tolerance of a variety of functional groups, and practicality. In addition, this protocol has been further elaborated in an intramolecular phenylselenation of a (hetero) aryl C-H bond to construct an important motif of benzoselenopheno[3,2-b]indole. A preliminary mechanism study suggests that the reaction starts with a Ullman-type selenation between aryl iodides and selenium, followed by an oxidative cross-coupling with indole. The utility of this method has been demonstrated in an efficient gram-scale synthesis and an application to the synthesis of tubulin polymerization inhibitor.

Copper-Catalyzed Oxirane-Opening Reaction with Aryl Iodides and Se Powder.

Using Se powder as the selenating reagent, the copper-catalyzed double C-Se cross-coupling of aryl iodides, epoxides, and elemental selenium has been developed. This strategy provides a straightforward approach to the synthesis of ß-hydroxy phenylselenides with excellent regioselectivity of the ring opening reaction. This process proceeds in generally good yields and is compatible with a broad range of functional groups.

Enhancement of N-heterocyclic carbenes on rhodium catalyzed olefination of triazoles.

A few rhodium complexes of N-heterocyclic carbenes were prepared through carbene transfer reactions and their structures were characterized by X-ray diffraction analysis. The rhodium complexes of NHCs are found to be efficient catalysts for vinylation of various triazoles via C-H activation. A number of double vinylated triazoles can be obtained in good yields.