A promoted SmI2 direct reaction of dibromoacetic acid with different aldehydes, followed by an elimination reaction also promoted by samarium diiodide, affords (E)-alpha,beta-unsaturated carboxylic acids 2 with total stereoselectivity. A mechanism to explain this transformation is proposed.
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http://dx.doi.org/10.1021/jo052236x | DOI Listing |
Chemosphere
January 2025
Faculty of Engineering, Hokkaido University, N13W8, Sapporo, 060-8628, Japan. Electronic address:
Global concern regarding transformation products (TPs) derived from contaminants, including pesticides, in the environment and during water treatment has been growing markedly. In the present study, we investigated the anti-acetylcholinesterase (AChE) activity of an aqueous solution of the organophosphorus insecticide disulfoton, a toxicological endpoint for determining the acceptable daily intake of disulfoton, both in the presence and the absence of metabolism during chlorination. Disulfoton rapidly reacted with free chlorine and completely disappeared within 0.
View Article and Find Full Text PDFJ Phys Chem B
January 2025
Department of Chemistry and Biochemistry, University of Arizona, 1306 East University Boulevard, Tucson, Arizona 85721, United States.
Natural enzymes are powerful catalysts, reducing the apparent activation energy for reactions and enabling chemistry to proceed as much as 10 times faster than the corresponding solution reaction. It has been suggested for some time that, in some cases, quantum tunneling can contribute to this rate enhancement by offering pathways through a barrier inaccessible to activated events. A central question of interest to both physical chemists and biochemists is the extent to which evolution introduces mechanisms below the barrier, or tunneling mechanisms.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
January 2025
University of Wisconsin Madison, Chemistry, 1101 University Ave, 53706, Madison, UNITED STATES OF AMERICA.
Many applications of enzymes benefit from activity on structurally diverse substrates. Here, we sought to engineer the decarboxylative aldolase UstD to perform a challenging C-C bond forming reaction with ketone electrophiles. The parent enzyme had only low levels of activity, portending multiple rounds of directed evolution and a possibility that mutations may inadvertently increase the specificity of the enzyme for a single model screening substrate.
View Article and Find Full Text PDFMol Biol Rep
January 2025
College of Veterinary Medicine, Qingdao Agricultural University, Qingdao, 266109, PR China.
Background: Feline diarrhea is a common digestive tract disease in clinical practice, with watery feces as the main clinical manifestation. There are numerous pathogenic factors causing feline diarrhea, among which viral infections are prevalent, and feline panleukopenia virus (FPV) is the most common pathogen. In recent years, a variety of novel viruses have been detected in the intestines of cats with diarrhea.
View Article and Find Full Text PDFJ Phys Chem A
January 2025
Center for Satellite Application on Environment, Ministry of Ecology and Environment, Beijing 100094, China.
The edge structures of carbonaceous materials exhibit temperature-dependent behavior on the atomic scale, with variations in the relative ratios of zigzag, reconstructed 5-7 zigzag (ZZ57), and armchair edges observed at different temperatures. Nevertheless, the mechanisms underlying the interconversion of these edge structures and the influence of the surrounding metals remain unclear. This study investigates the reconstruction and reversible transformation processes of ZZ57 edge structures in carbon materials and examines the effects of different metal atoms (Na, K, and Ca) by using density functional theory.
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