An iodine (I 2 )/tert-butyl hydroperoxide (TBHP)-mediated annulation cascade between yneallenones and sulfonyl hydrazides has been established, in which a wide set of dihydrobenzo[f] phthalazines were synthesized through one-pot, two-step strategy under metal-free conditions. The synthetic utility of these transformations leads to subsequent CÀ C and CÀ N bond-forming reactions to effectively build up functional aza-heterocycle with potential significance.
Comprehensive Summary
Developing reactions for the synthesis of 6‐6‐4 and 6‐4 carbocyclic scaffolds with a chiral quaternary center at the bridgehead position is highly desired, considering the existence of such skeletons in natural products with biological activities and the potential of using these molecules for downstream studies in chemical biology and medicinal chemistry. Report here is accessing these target skeletons with high chemo‐, regio‐ and enantio‐selectivities through Pd(II)/chiral N,N’‐disulfonyl bisimidazoline (Bim) ligand‐catalyzed asymmetric reaction of yne‐allenones and arylboronic acids. Realization of 6‐6‐4 skeleton with a ring‐junction all‐carbon stereocenter is a one‐step process while synthesizing 6‐4 skeleton is a two‐step process, which begins with intramolecular [2 + 2] reaction of allenes with alkynes, followed by Pd‐catalyzed asymmetric addition of arylboronic acids to cyclic enones generated in the first step. Noteworthy is that chiral Bim ligand as a C2‐symmetric N,N’‐bidentateanionic ligand, designed by us, in coordinating with Pd catalyst was first applied to catalyze asymmetric 1,4‐conjugate addition reaction with the high catalytic performance (the reaction can be carried out in air). DFT calculations have been applied to understand how these reactions take place, the origins of enantioselectivity, and relative reactivities of different substrates.
The electrochemical performance of tungsten oxide (WO3) is closely related to its morphology and lattice symmetry. However, current synthetic approaches are typically limited by product controllability, environmental friendliness, and low scalability. Here, a facile and high‐efficient synthesis is reported of WO3 nanosheets based on the synergistic intercalation and oxidation of layered tungsten disulfide (WS2). The complete conversion from WS2 to WO3 is confirmed by crystallographic, spectroscopic, microscopic, and elemental analysis. The prepared WO3 nanosheets exhibit a superior specific capacitance of 480 F g−1 at a current density of 1 A g−1 and a good cycling stability at a current density of 10 A g−1. Notably, benefitting from the 2D nanosheet structure and the high lattice symmetry, the cubic WO3 nanosheets possess a high specific capacitance of 384 F g−1 at a high current density of 20 A g−1, which is much higher than that of other WO3‐based electrode materials.
Summary
For an elementary study in vitro of probiotics with aid of antioxidant property for ameliorating oxidative stress, Lactobacillus pentosus subsp. FS4722, Lactobacillus plantarum subsp. FS5062, FS5382 and FS5498 were used to evaluate their antioxidant property via chemical‐based and cellular assays. A significant dose‐dependent manner was observed in the results of DPPH, ·OH and ·O2− radical‐scavenging activity. Principal component analysis (PCA), however, showed that the total antioxidant activity of four Lactobacillus was positively associated with their ability against H2O2‐induced HepG2 cell death, which indicated Lactobacillus pentosus FS4722 (95.07 ± 5.08%) had great potential for repairing oxidative damage in HepG2 cells oxidative stress model. The potential regulatory pathway of Lactobacillus FS4722 antioxidant action is reduction of intracellular ROS levels, improvement of SOD and CAT enzymes activities along with the activation of Nrf2 signalling and upregulation of the transcription levels of antioxidant factors NQO1, GCLG, GCLM and HO‐1.
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