Silver-Promoted Three-Component Synthesis of Perfluoroalkenyl Pyrroles through Partial Defluorinative Functionalization of Perfluoroalkyl Halides.

A silver-promoted three-component heterocyclization of alkynes, perfluoroalkyl halides, and 1,3-dinucleophiles was developed for the efficient synthesis of privileged (E)-perfluoroalkenyl pyrroles. The reaction proceeded through a rationally designed sequence of radical perfluoroalkylation and intramolecular defluorinative [3 + 2]-heterocyclization. The utility of perfluoroalkyl halide as a perfluoroalkenyl reagent, by selective and controllable functionalization of two inert C(sp3)-F bonds at vicinal carbon centers on the perfluoroalkyl chain, provides a new reaction mode for the synthesis of value-added organofluorides starting from the easily available and low-cost fluorinated feedstock.

Transition-Metal-Free Hydrodefluoroamination of Trifluoromethyl Enones for the Synthesis of α-Fluoroenamides.

A three-component strategy was developed to enable hydrodefluoroamination of ß-trifluoromethyl enones by selectively activating two C(sp3)-F bonds in the trifluoromethyl group. The method involved a sequence of carbonyl reduction, hydrodefluorination, and defluoroamination under transition-metal-free conditions. Synthetically useful (E)-stereospecific α-fluoroenamides were obtained in good yields with diverse functional group tolerance, which could be easily transformed into valuable organofluorides and heterocycles. The carbonyl auxiliary exerts both electronic and steric impacts on the CF3-alkenes, allowing for controllable and selective defluorination.

Palladium-Catalyzed Esterification of Aryl Fluorosulfates with Aryl Formates.

An efficient palladium-catalyzed carbonylation of aryl fluorosulfates with aryl formates for the facile synthesis of esters was developed. The cross-coupling reactions proceeded effectively in the presence of a palladium catalyst, phosphine ligand, and triethylamine in DMF to produce the corresponding esters in moderate to good yields. Of note, functionalities or substituents, such as nitro, cyano, methoxycarbonyl, trifluoromethyl, methylsulfonyl, trifluoromethoxy, fluoro, chloro, bromo, methyl, methoxy, N,N-dimethyl, and [1,3]dioxolyl, were well-tolerated in the reactions, which could be kept for late-stage modification. The reactions employing readily available and relatively robust aryl fluorosulfates as coupling electrophiles could potentially serve as an attractive alternative to traditional cross-couplings with the use of aryl halides and pseudohalides as substrates.

Hydroxylation of Aryl Sulfonium Salts for Phenol Synthesis under Mild Reaction Conditions.

Hydroxylation of aryl sulfonium salts could be realized by utilizing acetohydroxamic acid and oxime as hydroxylative agents in the presence of cesium carbonate as a base, leading to a variety of structurally diverse hydroxylated arenes in 47-95% yields. In addition, the reaction exhibited broad functionality tolerance, and a range of important functional groups (e.g., cyano, nitro, sulfonyl, formyl, keto, and ester) could be well amenable to the mild reaction conditions.

Combining Hydrodefluorination and Defluorophosphorylation for Chemo- and Stereoselective Synthesis of gem-Fluorophosphine Alkenes.

A chemo-, regio-, and stereoselective reaction of trifluoromethyl enones, phenylsilane, and phosphine oxides through a sequential hydrodefluorination and defluorophosphorylation relay is developed for the synthesis of distinctive gem-fluorophosphine alkenes. This multicomponent reaction occurred under transition-metal-free conditions with good functional group tolerance. Moreover, the preinstalled carbonyl auxiliary is important for tuning the reactivity of ß-trifluoromethyl enones, thereby enabling controllable and selective functionalization of two fluorine atoms in trifluoromethylated enones.

Nickel-Catalyzed Direct Cross-Coupling of Unactivated Aryl Fluorides with Aryl Bromides.

A nickel-catalyzed direct cross-coupling of unactivated aryl fluorides with aryl bromides is realized. The one-pot reaction, which avoids the use of preformed and sensitive organometallic reagents, proceeds effectively via C-F bond cleavage at room temperature in THF in the presence of the phosphine ligand and magnesium powder (with or without TMSCl) to produce the desired biaryls in modest to good yields.

Na2S·9H2O Enabled Defluorodisulfuration and Hydrodefluorination of Perfluorobutyl Tetralones: Synthesis of Trifluoromethyl 1,2-Dithioles.

An unprecedented defluorocyclization of perfluorobutyl tetralones with Na2S·9H2O was developed for the synthesis of trifluoromethyl 1,2-dithioles, which provided chemists novel access to biologically and pharmaceutically relevant organofluorides. Successive C(sp3)-F bond functionalization at the perfluoroalkyl chain is vital for the formation of four C-H/C-S/S-S bonds and a five-membered S-heterocycle assembly. Cheap, weakly toxic, and odorless inorganic sulfide Na2S·9H2O acts as both a disulfurating precursor and a hydrodefluorinating reagent in this tandem multi-bond-interconverting reaction.

Selective and Controllable Defluorophosphination and Defluorophosphorylation of Trifluoromethylated Enones: An Auxiliary Function of the Carbonyl Group.

The auxiliary function of a carbonyl group in the tunable defluorophosphination and defluorophosphorylation of trifluoromethylated enones with P(O)-containing compounds was demonstrated. Controlled replacement of one or two fluorine atoms in trifluoromethylated enones while maintaining high chemo- and stereoselectivity was achieved under mild conditions, thus enabling diversity-oriented synthesis of skeletally diverse organophosphorus libraries─(Z)-difluoro-1,3-dien-1-yl phosphinates, (1Z,3E)-4-phosphoryl-4-fluoro-buta-1,3-dien-1-yl phosphinates, and (E)-4-phosphoryl-4-fluoro-1,3-but-3-en-1-ones─in good yields with excellent functional group tolerance.

Nickel-Catalyzed Direct Cross-Coupling of Aryl Thioether with Aryl Bromide.

A straightforward cross-coupling of aryl thioether with aryl bromide with the aid of nickel salt, magnesium, and lithium chloride in tetrahydrofuran at ambient temperature was accomplished. The one-pot reactions proceeded efficiently via C-S bond cleavage to produce the desired biaryls in modest to good yields, avoiding the use of pregenerated or commercial organometallic reagents.

Nickel-Catalyzed Direct Cross-Coupling of Aryl Fluorosulfates with Aryl Bromides.

A one-pot, direct cross-coupling of aryl fluorosulfate with aryl bromide, which is step-economical and avoids the use of a preprepared/commercial organometallic reagent, could be accomplished by performing the reaction in THF at room temperature in the presence of nickel catalyst, magnesium turnings, and lithium chloride, giving rise to the corresponding biaryls in moderate to good yields with reasonable functional group compatibility.

Dual Role of (NH4)2CO3 Enables Defluorinative Synthesis of ß-Fluoroalkylated Aminovinyl Ketones.

A modular multicomponent reaction of readily available fluoroalkyl alkenes, amidines, ammonium carbonate, and water was developed for the facile construction of ß-fluoroalkylated aminovinyl ketones, which provided chemists a novel access to value-added organofluorine compounds. The reaction proceeded regio-/stereoselectively under mild conditions and exhibited good functional group tolerance. Cheap, stable, and low-toxic inorganic salt (NH4)2CO3 was first found to act as both a nitrogen source and a carbonyl equivalent in the multi-bond-forming process.

Prism-like bimetallic (Ni-Co) alkaline carboxylate-based non-enzymatic sensor capable of exceptionally high catalytic activity towards glucose.

In this study, we fabricated a novel non-enzymatic glucose sensor based on prism-like bimetallic alkaline carboxylate (CoNi-MIM). The morphology and structure of CoNi-MIM were carefully investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), powder X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The electrochemical glucose oxidation of the synthesized sensor was then explored by cyclic voltammetry (CV) and chronoamperometry in alkaline medium. It was found that CoNi-MIM is the optimal choice with a remarkably high sensitivity of 5024.4 µA mM-1 cm-2, low detection limit of 56.1 nM (S/N = 3), linear response of up to 14.3 mM and excellent selectivity compared to Co-MIM, CoFe-MIM and CoMn-MIM. Furthermore, the as-fabricated sensor demonstrated appreciable practicality for the determination of glucose in real samples. These results indicate that CoNi-MIM holds a good application prospect in non-enzymatic glucose sensing.

Nickel-Catalyzed Direct Cross-Coupling of Diaryl Sulfoxide with Aryl Bromide.

The direct cross-couplings of diaryl sulfoxides with aryl bromides via C-S bond cleavage could be readily accomplished using nickel(II) as the catalyst, 1,2-bis(diphenylphosphino)ethane (dppe) as the ligand, and magnesium turnings as the reducing metal in THF, leading to the corresponding biaryls in moderate to good yields. The reaction exhibited a broad substrate scope and could be applied to a gram-scale synthesis. The "one-pot" reaction, which avoids the utility of presynthesized and moisture-labile organometallic compounds, is operationally simple and step-economic.

DMSO-Promoted Difluoroalkylation of Organophosphonium Salts with Difluoroenol Silyl Ethers.

An efficient method for the synthesis of ß,ß-di(hetero)aryl-α,α-difluorinated ketones using readily available organophosphonium salts and difluoroenol silyl ethers has been developed. This mild reaction features a good functional group tolerance, a scaled-up synthesis, and synthetic simplicity. By taking advantage of DMSO as a less-toxic promoter and solvent for the difluoroalkylation and C-P bond functionalization, the use of transition-metal catalysts and sensitive additives could be avoided.

Palladium-Catalyzed Sonogashira Coupling of a Heterocyclic Phosphonium Salt with a Terminal Alkyne.

An efficient Sonogashira coupling of a heterocyclic phosphonium salt with a terminal alkyne via C-P bond cleavage was developed. The reactions proceeded smoothly in the presence of palladium catalyst, copper(I) iodide, and N,N-diisopropylethylamine (DIPEA) in N-methyl-2-pyrrolidone (NMP) at 100 °C for 12 h, producing the corresponding alkynyl-substituted pyridine, quinoline, pyrazine, and quinoxaline in moderate to good yields with wide substrate scope and broad functional group tolerance. In addition, gram-scale synthesis could also be achieved, and the reaction could be applied to the functionalization of alkyne-containing complex molecules derived from sugars and pharmaceutical and naturally occurring products (e.g., estrone, d-galactopyranose, menthol, and ibuprofen).

Fabrication of Ag nanoparticles coupled with ferrous disulfide biocatalyst as a peroxidase mimic for sensitive electrochemical and colorimetric dual-mode biosensing of H2O2.

Ag nanoparticles (Ag NPs) with high electrocatalytic activity are of great significance for electrochemical sensors. Nanostructures as scaffold can solve aggregation problem of Ag NPs so that to ensure the stability. In this work, Ag NPs immobilized on FeS2 nanoprisms (Ag/FeS2) were prepared via an in-situ photocatalytic reduction approach. The enlarged electrode effective surface area, enhanced electron transfer and the synergic impact between Ag NPs and FeS2 lead to an enhanced catalytic activity. The electrochemical detection method exhibited great performance of low detection limit (0.6 µM), wide linear range and high sensitivity (244.4 µA mM-1 cm-2) for H2O2. Moreover, Ag/FeS2 as a peroxidase mimic can catalyze oxidation of colorless 3,3',5,5'-tetramethylbenzidine (TMB) to blue product (oxTMB) by H2O2, which achieved effective detection of H2O2 with a 3.0 µM detection limit. A promising way was successfully eatablished to perform the quantitation of H2O2 in serum and beverage.

Nickel-Catalyzed Direct Cross-Coupling of Aryl Sulfonium Salt with Aryl Bromide.

The direct cross-couplings of aryl sulfonium salts with aryl halides could be achieved by using nickel as a reaction catalyst. The reactions proceeded efficiently via C-S bond activation in the presence of magnesium turnings and lithium chloride in THF at ambient temperature to afford the corresponding biaryls in moderate to good yields, potentially serving as an attractive alternative to conventional cross-coupling reactions employing preprepared organometallic reagents.

Facile construction of an Ag/MoSe2 composite based non-enzymatic amperometric sensor for hydrogen peroxide.

We report an electrochemical non-enzymatic method for hydrogen peroxide (H2O2) detection based on Ag nanoparticle-decorated MoSe2 (Ag/MoSe2-500) hybrid nanostructures. These hybrid nanocomposites are easily prepared by in situ reduction of Ag+ on the surface of MoSe2. Benefiting from the strong synergy of Ag nanoparticles and MoSe2 nanosheets in enhancing electrical conductivity, the Ag/MoSe2-500 hybrid nanostructures perform excellent sensing activity for H2O2 electrocatalytic reduction with a wide linear range of 0.02-15.2 mM, a high sensitivity of 400.0 µA mM-1 cm-2 and a low detection limit of 0.39 µM (S/N = 3). Furthermore, the sensor displays satisfactory reproducibility and stability and is applicable for practical quantitative analysis of H2O2 in milk and orange juice samples. In a word, Ag/MoSe2-500 nanocomposites are promising candidates for non-enzymatic H2O2 sensing in the fields of biology and food science.

Efficient improvement in non-enzymatic glucose detection induced by the hollow prism-like NiCo2S4 electrocatalyst.

Hollow prism-like NiCo2S4 materials (NiCo2S4 HNPs) were successfully fabricated by a two-step method. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and powder X-ray diffraction (XRD) confirmed the morphology and structure of the as-prepared NiCo2S4 nanoprisms. A non-enzymatic sensor based on NiCo2S4 HNPs was constructed with outstanding electrochemical activity towards glucose oxidation in alkaline medium. The sensor showed a rapid response time (∼0.1 s), a high sensitivity of 82.9 µA mM-1 cm-2, a wide linear range (0.005-20.2 mM) and a detection limit of 0.8 µM (S/N = 3) with a good selectivity and reproducibility. Additionally, the proposed electrode also confirmed the feasibility in practical blood serum. These results indicate that NiCo2S4/ITO has great potential in the development of non-enzymatic glucose sensor applications.

Titanium(IV)-Mediated Ring-Opening/Dehydroxylative Cross-Coupling of Diaryl-Substituted Methanols with Cyclopropanol Derivatives.

A titanium(IV)-mediated ring-opening/dehydroxylative cross-coupling of diaryl-substituted methanols with a cyclopropanol derivative was developed. The reactions proceeded efficiently to provide synthetically useful γ,γ-diaryl esters in moderate to good yields, which could be applied to the functionalization of complex molecules derived from bioactive fenofibrate and isoxepac and the synthesis of a precursor of Zoloft.