The regioselective C-H activation of arenes remains one of the most promising techniques for accessing highly important functionalized motifs. Such functionalizations can generally be achieved through directed and non-directed processes. The directed approach requires a covalently attached directing group (DG) on the substrate to induce reactivity and selectivity and therefore intrinsically leaves a functional group at the point of attachment within the molecule, even after the tailored DG has been removed. Conversely, non-directed methods typically suffer from regioselectivity issues, especially for unbiased substrates. Herein, we report a unique approach that employs weak charge-charge and charge-dipole interactions to enable the -selective activation and olefination of arenes to address these challenges in Pd catalysis. The charged moiety can easily be converted to uncharged simple arenes by hydrogenation or cross-coupling. In-depth mechanistic studies prove that the charge is responsible for the observed selectivity. We expect our studies to be generalizable and thereby enable further regioselective transformations.
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http://dx.doi.org/10.1016/j.chempr.2022.12.019 | DOI Listing |
Acta Cir Bras
January 2025
Universidade Federal Rural de Pernambuco - Programa de Pós-Graduação em Medicina Veterinária - Departamento de Morfologia e Fisiologia Animal - Recife (PE) - Brazil.
Purpose: To evaluate whether the effectiveness of topical antiseptic solutions in restoring skin continuity solutions is related to their antimicrobial action or to their action in maintaining moisture, in dogs undergoing elective surgeries.
Methods: Forty dogs, 20 males and 20 females, underwent orchiectomy and oophorectomy, respectively. Thereafter, the animals were allocated into four groups (n = 5) and treated with different topical solutions: polyhexanide 0.
Environ Technol
January 2025
State Key Laboratory of Heavy Oil Processing, Beijing Key Lab of Oil & Gas Pollution Control, China University of Petroleum-Beijing, Beijing, People's Republic of China.
Oxidants used in the ISCO technology usually require activation by activators to degrade contaminants. However, this study investigated degradation of 15 typical halogenated hydrocarbons by five common ISCO oxidants (PS, PMS, HO, KMnO, SPC) without activation in both pure water and real groundwater. Unactivated PS could degrade 14 halogenated hydrocarbons, excluding tetrachloromethane.
View Article and Find Full Text PDFActa Neurobiol Exp (Wars)
January 2025
Applied Biomedical Research Center, Mashhad University of Medical Sciences, Mashhad, Iran.
Piperine is an amide alkaloid isolated from the black pepper plant. This study examined the pain‑relieving activity of piperine against paclitaxel (PTX)‑induced neuropathy. Male mice were divided into 6 groups: Sham‑operated group (remained intact), PTX group (PTX‑treated mice receiving normal saline), PTX+ piperine 10, 25, and 50 mg/kg groups (PTX‑treated mice receiving piperine) and positive control group (PTX‑treated mice receiving imipramine 10 mg/kg).
View Article and Find Full Text PDFJ Am Chem Soc
January 2025
Department of Chemistry, The Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla, California 92037, United States.
The development of catalytic methods for the synthesis of enantiopure saturated heterocycles has been a long-standing challenge in asymmetric catalysis. We describe the first highly enantioselective palladium-catalyzed βC(sp)-H arylation and olefination of lactams for the preparation of various chiral N-heterocycles bearing quaternary carbon centers. The presence of strongly electron-withdrawing groups on the chiral bifunctional MPAThio ligand is crucial to the reactivity of weakly coordinating lactams.
View Article and Find Full Text PDFPhysiol Plant
January 2025
Department of Biology, University of Konstanz, Konstanz, Germany.
Diatoms dominate phytoplankton communities in turbulent waters, where light fluctuations can be frequent and intense. Due to this complex environment, these heterokont microalgae display remarkable photoprotection strategies, including a fast Non-Photochemical Quenching (NPQ). However, in nature, several abiotic parameters (such as temperature) can influence the response of photosynthetic organisms to light stress in a synergistic or antagonistic manner.
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