Enantioselective electrophilic aromatic nitration methodology is needed to advance chirality-assisted synthesis (CAS). Reported here is an enantioselective aromatic nitration strategy operating with chiral diester auxiliaries, and it provides an enantioselective synthesis of a C -symmetric tribenzotriquinacene (TBTQ). These axially-chiral structures are much sought-after building blocks for CAS, but they were not accessible prior to this work in enantioenriched form without resolution of enantiomers. This nitration strategy controls the stereochemistry of threefold nitration reactions from above the aromatic rings with chiral diester arms. Dicarbonyl-to-arenium chelation rigidifies the reaction systems, so that remote stereocenters position the ester-directing groups selectively over specific atoms of the TBTQ framework. Closely guided by computational design, a more selective through-space directing arm was first predicted with density functional theory (DFT), and then confirmed in the laboratory, to outperform the initial structural design. This enantio- and regioselective TBTQ synthesis opens a new pathway to access building blocks for CAS.
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http://dx.doi.org/10.1002/anie.201811517 | DOI Listing |
J Mol Model
January 2025
Department of Chemistry, Military Institute of Engineering, Praça General Tibúrcio 80, Rio de Janeiro, Brazil.
Context: Nitrocellulose, widely used in energetic materials, is prone to thermal and chemical degradation, compromising safety and performance. Stabilizers are molecules used in the composition of nitrocellulose-based propellants to inhibit the autocatalytic degradation process that produces nitrous gases and free nitric acids. Curcumin, (1E,6E)-1,7-bis(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione, known for its antioxidant properties and a potential green stabilizer, was investigated using Density Functional Theory (DFT) focusing on its interaction with nitrogen dioxide.
View Article and Find Full Text PDFSci Rep
December 2024
Centro de Investigación en Materiales Avanzados S.C. (CIMAV-Mty), Unidad Monterrey, Alianza Norte 202, Apodaca, N.L., C.P. 66628, Mexico.
This research investigates the concentrations, sources, and health risks of polycyclic aromatic hydrocarbons (PAHs) and nitrated PAHs (NPAHs) in particulate matter with an aerodynamic diameter of 10 μm or less (PM[Formula: see text]) from critical urban centers in northern Mexico: Metropolitan Monterrey Area (MMA), Chihuahua (CHI), and Ciudad Juárez (CDJ). Advanced gas chromatography-mass spectrometry (GC-MS and GC-NCI-MS) revealed significant PAHs concentrations, with levels in MMA reaching 108.89 ± 99.
View Article and Find Full Text PDFJACS Au
December 2024
State Key Laboratory of Fine Chemicals, School of Chemistry, Dalian University of Technology, Dalian 116024, China.
Nitroaromatics, as an important member and source of nitrogen-containing aromatics, is bringing enormous economic benefits in fields of pharmaceuticals, dyes, pesticides, functional materials, fertilizers, and explosives. Nonetheless, the notoriously polluting nitration industry, which suffers from excessive discharge of fumes and waste acids, poor functional group tolerance, and tremendous purification difficulty, renders mild, efficient, and environmentally friendly nitration a formidable challenge. Herein, we develop a visible-light-driven biocompatible arene C-H nitration strategy with good efficiency and regioselectivity, marvelous substrate applicability and functional group tolerance, and wide application in scale-up synthesis, total synthesis, and late-stage functionalization.
View Article and Find Full Text PDFJ Hazard Mater
December 2024
Key Laboratory of Eco-Environments in Three Gorges Reservoir Region, Ministry of Education, College of Environment and Ecology, Chongqing University, Chongqing 400045, PR China.
Carbonate radical (CO) is inevitably produced in advanced oxidation processes (AOPs) when addressing real-world aqueous environments, yet it often goes unnoticed due to its relatively lower reactivity. In this study, we emphasized the pivotal role of CO in targeting the elimination of contaminants by contrasting it with conventional reactive oxygen species (ROSs) and assessing the removal of sulfamethazine (SMT). Similar to singlet oxygen (O), CO shows a preference for electron-rich organic compounds.
View Article and Find Full Text PDFFront Chem
December 2024
Department of Chemistry and Institute of Chemical Biology and Drug Discovery, Stony Brook University, Stony Brook, NY, United States.
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