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Epidemiological studies have suggested that inhalation exposure to particulate matter (PM) air pollution, especially fine particles (i.e., PM2.5 (PM with an aerodynamic diameter of 2.5 microns or less)), is causally associated with cardiovascular health risks. To explore the toxicological mechanisms behind the observed adverse health effects, the hemolytic activity of PM2.5 samples collected during different pollution levels in Beijing was evaluated. The results demonstrated that the hemolysis of PM2.5 ranged from 1.98% to 7.75% and demonstrated a clear dose–response relationship. The exposure toxicity index (TI) is proposed to represent the toxicity potential of PM2.5, which is calculated by the hemolysis percentage of erythrocytes (red blood cells, RBC) multiplied by the mass concentration of PM2.5. In a pollution episode, as the mass concentration increases, TI first increases and then decreases, that is, TI (low pollution levels) < TI (heavy pollution levels) < TI (medium pollution levels). In order to verify the feasibility of the hemolysis method for PM toxicity detection, the hemolytic properties of PM2.5 were compared with the plasmid scission assay (PSA). The hemolysis results had a significant positive correlation with the DNA damage percentages, indicating that the hemolysis assay is feasible for the detection of PM2.5 toxicity, thus providing more corroborating information regarding the risk to human cardiovascular health. [ABSTRACT FROM AUTHOR]

Organic molecules bearing chiral sulfur stereocenters exert a great impact on asymmetric catalysis and synthesis, chiral drugs, and chiral materials. Compared with acyclic ones, the catalytic asymmetric synthesis of thio‐heterocycles has largely lagged behind due to the lack of efficient synthetic strategies. Here we establish the first modular platform to access chiral thio‐oxazolidinones via Pd‐catalyzed asymmetric [3+2] annulations of vinylethylene carbonates with sulfinylanilines. This protocol is featured by readily available starting materials, and high enantio‐ and diastereoselectivity. In particular, an unusual effect of a non‐chiral supporting ligand on the diastereoselectivity was observed. Possible reaction mechanisms and stereocontrol models were proposed. [ABSTRACT FROM AUTHOR]

The development of a mild and general method for C(sp3)−H functionalization of cyclic amines has been an ongoing challenge. In this work, we describe the copper‐catalyzed enantioselective C(sp3)−H alkynylation of unactivated cyclic 2‐iodo‐benzamide under photo‐irradiation by intramolecular 1,5‐hydrogen atom transfer (HAT). The employment of a new bisoxazoline diphenylamine ligand, in conjunction with 1,1′‐bi‐2‐naphthol, which significantly improved the reduction potential of the copper complex, was the key to success of this chemistry. Mechanistic and computational studies supported that the new copper complex served the dual role as a photoredox and coupling catalyst, the reaction went through a radical process, and the intramolecular 1,5‐HAT process was involved in the rate‐limiting step. Apart from the broad substrate scope including unprecedented benzocyclic amines, this method also showed excellent diastereoselectivity in 2‐monosubstituted cyclic amines via substrate control. [ABSTRACT FROM AUTHOR]

Organic molecules bearing chiral sulfur stereocenters exert a great impact on asymmetric catalysis and synthesis, chiral drugs, and chiral materials. Compared with acyclic ones, the catalytic asymmetric synthesis of thio-heterocycles has largely lagged behind due to the lack of efficient synthetic strategies. Here we establish the first modular platform to access chiral thio-oxazolidinones via Pd-catalyzed asymmetric [3+2] annulations of vinylethylene carbonates with sulfinylanilines. This protocol is featured by readily available starting materials, and high enantio- and diastereoselectivity. In particular, an unusual effect of a non-chiral supporting ligand on the diastereoselectivity was observed. Possible reaction mechanisms and stereocontrol models were proposed., (© 2024 Wiley-VCH GmbH.)

Transition-metal clusters have attracted great attention in catalysis due to their unique reactivity and electronic properties, especially for novel substrate binding and activation modes at the bridging coordination sites of metal clusters. Although palladium complexes have demonstrated outstanding catalytic performance in various transformations, the catalytic behaviors of polynuclear palladium clusters in many important synthetic methodologies remain much less explored so far. Herein, we disclose the use of an atomically defined tri-nuclear palladium (Pd 3 Cl) species as a catalyst precursor in Ag(I)-assisted direct C-H arylation with aryl iodides under mild conditions. This catalyst system leads to the formation of synthetically important biaryls in good yields with high site selectivities without the assistance of directing groups.

The nickel-catalyzed cross-electrophile coupling of 1,2,3-benzotriazin-4(3 H )-ones with aryl bromides to generate a diverse array of ortho -arylated benzamide derivatives has been developed. The reaction displayed good functional group tolerance with Zn as the reductant. The key to this transformation is the ring opening of benzotriazinones, which undergo a denitrogenative process to obtain various benzamide derivatives (29 examples, 42-93% yield). The scalability of this transformation was demonstrated.

The development of a mild and general method for C(sp 3 )-H functionalization of cyclic amines has been an ongoing challenge. In this work, we describe the copper-catalyzed enantioselective C(sp 3 )-H alkynylation of unactivated cyclic 2-iodo-benzamide under photo-irradiation by intramolecular 1,5-hydrogen atom transfer (HAT). The employment of a new bisoxazoline diphenylamine ligand, in conjunction with 1,1'-bi-2-naphthol, which significantly improved the reduction potential of the copper complex, was the key to success of this chemistry. Mechanistic and computational studies supported that the new copper complex served the dual role as a photoredox and coupling catalyst, the reaction went through a radical process, and the intramolecular 1,5-HAT process was involved in the rate-limiting step. Apart from the broad substrate scope including unprecedented benzocyclic amines, this method also showed excellent diastereoselectivity in 2-monosubstituted cyclic amines via substrate control., (© 2022 Wiley-VCH GmbH.)