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Pyridine motifs are widespread pharmacophores in many drugs. Installing various substituents through pyridine C−H bond functionalization is significant for new drug design and discovery. Developments of late‐stage functionalization reactions enrich the strategies for selective functionalization of pyridines. However, late‐stage C−H carboxylation of pyridines is a long‐standing challenge, especially selectively carboxylation with CO2 on pyridine motifs. Herein, we describe a practical method for C4−H carboxylation of pyridines via one‐pot C−H phosphination and copper‐catalyzed carboxylation of the resulted phosphonium salts with CO2. The reaction is conducted under mild conditions and compatible with multiple active groups and several pyridine drugs, providing diverse valuable isonicotinic acid compounds, demonstrating the application potential of this strategy. [ABSTRACT FROM AUTHOR]

Carboxyl group is one of the most widely used groups in organic synthesis. Herein, an efficient copper‐catalyzed carboxylation of aryl thianthrenium salts with carbon dioxide (CO2) at room temperature has been developed. The reaction employs low loading of cuprous chloride catalyst under 1 atm CO2 and exhibits good functional group tolerance. In combination with C−H thianthrenation of aromatic hydrocarbons, this work provides an efficient method for the site‐selective C−H carboxylation of aromatic hydrocarbons. It may serve as a significant late‐stage carboxylation tool for the modification of drug molecules in the future. [ABSTRACT FROM AUTHOR]

Carboxyl group is one of the most widely used groups in organic synthesis. Herein, an efficient copper‐catalyzed carboxylation of aryl thianthrenium salts with carbon dioxide (CO2) at room temperature has been developed. The reaction employs low loading of cuprous chloride catalyst under 1 atm CO2 and exhibits good functional group tolerance. In combination with C−H thianthrenation of aromatic hydrocarbons, this work provides an efficient method for the site‐selective C−H carboxylation of aromatic hydrocarbons. It may serve as a significant late‐stage carboxylation tool for the modification of drug molecules in the future. [ABSTRACT FROM AUTHOR]

Carboxyl group is one of the most widely used groups in organic synthesis. Herein, an efficient copper‐catalyzed carboxylation of aryl thianthrenium salts with carbon dioxide (CO2) at room temperature has been developed. The reaction employs low loading of cuprous chloride catalyst under 1 atm CO2 and exhibits good functional group tolerance. In combination with C−H thianthrenation of aromatic hydrocarbons, this work provides an efficient method for the site‐selective C−H carboxylation of aromatic hydrocarbons. It may serve as a significant late‐stage carboxylation tool for the modification of drug molecules in the future. [ABSTRACT FROM AUTHOR]

Carboxyl group is one of the most widely used groups in organic synthesis. Herein, an efficient copper‐catalyzed carboxylation of aryl thianthrenium salts with carbon dioxide (CO2) at room temperature has been developed. The reaction employs low loading of cuprous chloride catalyst under 1 atm CO2 and exhibits good functional group tolerance. In combination with C−H thianthrenation of aromatic hydrocarbons, this work provides an efficient method for the site‐selective C−H carboxylation of aromatic hydrocarbons. It may serve as a significant late‐stage carboxylation tool for the modification of drug molecules in the future. [ABSTRACT FROM AUTHOR]

-X- and [gamma]-rays' energy deposition in plastic scintillation fibers and fiber arrays in an energy range from 10 ke V to 20 MeV has been studied using Monte Carlo simulations. The results show that the characteristics of the energy deposition in fibers are similar to that observed in bulk scintillation materials. The deposition efficiency increases with the fiber length, but the rate of increase drops as the length of the fibers is beyond 8 cm, suggesting such a length might be the optimum thickness of an imaging plate constructed using the scintillation fiber arrays. The results suggest that plastic scintillation fibers are useful for X- and -y-ray imaging below about 1 MeV. For incident photons above that energy, the energy leakages from a fiber and crosstalk between fibers in an array become severe, which results in significant deteriorations in spatial resolution of the fiber arrays used for imaging. Index Terms--Energy deposition, Geant4, plastic scintillating fiber.

Pyridine motifs are widespread pharmacophores in many drugs. Installing various substituents through pyridine C-H bond functionalization is significant for new drug design and discovery. Developments of late-stage functionalization reactions enrich the strategies for selective functionalization of pyridines. However, late-stage C-H carboxylation of pyridines is a long-standing challenge, especially selectively carboxylation with CO 2 on pyridine motifs. Herein, we describe a practical method for C4-H carboxylation of pyridines via one-pot C-H phosphination and copper-catalyzed carboxylation of the resulted phosphonium salts with CO 2 . The reaction is conducted under mild conditions and compatible with multiple active groups and several pyridine drugs, providing diverse valuable isonicotinic acid compounds, demonstrating the application potential of this strategy., (© 2024 Wiley-VCH GmbH.)

The Grignard-type nucleophilic addition of C(sp 2 )-H bonds to aldehydes catalyzed by high-oxidation-state transition metal complexes is limited to activated aldehydes. Herein, we report the first example of Grignard-type nucleophilic addition of C(sp 2 )-H bonds to unactivated aldehydes catalyzed by high-oxidation-state ruthenium(II). The reaction has mild reaction conditions and good functional group tolerance. The corresponding alcohol products are obtained in good to excellent yields.

Microcystin-LR (MC-LR), the most toxic and commonly encountered cyanotoxin, is produced by harmful cyanobacterial blooms and potentially threatens human and ecosystems health. Titanium dioxide (TiO 2 ) photocatalysis is attracting growing attention and has been considered as an efficient, environmentally friendly and promising solution to eliminate MC-LR in the aquatic ecosystems. Over recent decades, scientific efforts have been directed towards the understanding of fundamentals, modification strategies, and application potentials of TiO 2 photocatalysis in degrading MC-LR. In this article, recent reports have been reviewed and progress has been summarized in the development of heterogeneous TiO 2 -based photocatalysts for MC-LR photodegradation under visible, UV, or solar light. The proposed photocatalytic principles of TiO 2 and destruction of MC-LR have been thoroughly discussed. Specifically, some main modification methods for improving the drawbacks and performance of TiO 2 nanoparticle were highlighted, including element doping, semiconductor coupling, immobilization, floatability amelioration and magnetic separation. Moreover, the performance evaluation metrics quantum yield (QY) and figure of merit (FOM) were used to compare different photocatalysts in MC-LR degradation. The best performance was seen in N-TiO 2 with QY and FOM values of 2.20E-07 molecules/photon and 1.00E-11 mol·L/(g·J·h). N-TiO 2 or N-TiO 2 -based materials may be excellent options for photocatalyst design in terms of MC-LR degradation. Finally, a summary of the remaining challenges and perspectives on new tendencies in this exciting frontier and still an emerging area of research were addressed accordingly. Overall, the present review will offer a deep insight for understanding the photodegradation of MC-LR with modified TiO 2 to further inspire researchers that work in associated fields., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Palladium-catalyzed arylation of unactivated β-C(sp 3 )-H bonds in carboxylic acid derivatives with aryl iodides is described for the first time using 2-amino-5,6-difluorophenyl-1 H -pyrazole as an efficient and readily removable directing group. Two fluoro groups are installed at the 5- and 6-position of the anilino moiety in 2-aminophenyl-1 H -pyrazole, clearly enhancing the directing ability of the auxiliary. In addition, the protocol employs Cu(OAc) 2 /Ag 3 PO 4 (1.2/0.3) as additives, evidently reducing the stoichiometric amount of expensive silver salts. Furthermore, this process exhibits high β-site selectivity, compatibility with diverse substrates containing α-hydrogen atoms, and excellent functional group tolerance.