Treatment of aromatic and heteroaromatic methyl ketones with sulfur monochloride and catalytic amounts of pyridine in refluxing chlorobenzene leads to the formation of acyl chlorides. Both electron-rich and electron-poor aryl methyl ketones can be used as starting materials. The resulting C1-byproduct depends on the precise reaction conditions chosen.
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http://dx.doi.org/10.1021/acs.joc.5b01707 | DOI Listing |
Tetrahedron
February 2025
Department of Chemistry, Western Washington University, Bellingham, WA 98225 (USA).
Beta-hydroxy ketones can be reduced using a sequence of ruthenium-catalyzed silyl etherification followed by tetrabutylammonium fluoride (TBAF) promoted intramolecular hydrosilylation. Switching from TBAF to tetrabutylammonium difluorotriphenylsilicate (TBAT), even without first forming the silyl ether, gave cyclic dioxasilinane products. These somewhat sensitive compounds could be isolated pure by column chromatography using florisil as the stationary phase.
View Article and Find Full Text PDFFood Chem X
January 2025
Key Laboratory of Geriatric Nutrition and Health (Beijing Technology and Business University), Ministry of Education, Beijing 100048, PR China.
In this study, raw milk was collected from three different grades of pastures and processed by pasteurization, blending and ultra-high temperature sterilization (UHT) in a factory production line with a feed size of 10 tons. Additionally, all samples (from raw milk to UHT milk samples) were analyzed by -nose and GC-MS. Key flavor compounds such as 2-heptanone, hexanal, nonanal, 3-methyl-butanal, and dimethyl sulfide were found.
View Article and Find Full Text PDFMolecules
December 2024
Department of Biochemistry and Molecular Biology, Graduate School of Medical Science, Yamagata University, Yamagata 990-9585, Japan.
Leucine, isoleucine, and valine are collectively known as branched chain amino acids (BCAAs) and are often discussed in the same physiological and pathological situations. The two consecutive initial reactions of BCAA catabolism are catalyzed by the common enzymes referred to as branched chain aminotransferase (BCAT) and branched chain α-keto acid dehydrogenase (BCKDH). BCAT transfers the amino group of BCAAs to 2-ketoglutarate, which results in corresponding branched chain 2-keto acids (BCKAs) and glutamate.
View Article and Find Full Text PDFCatal Sci Technol
December 2024
Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern Freiestrasse 3 3012 Bern Switzerland
Even though α-arylation of ketones is attractive for direct C-H functionalization of organic substrates, the method largely relies on phosphine-ligated palladium complexes. Only recently, efforts have focused on developing nitrogen-based ligands as a more sustainable alternative to phosphines, with pyridine-functionalized pyridinium amidate (pyr-PYA) ,'-bidentate ligands displaying good selectivity and activity. Here, we report on a second generation set of catalyst precursors that feature a 5-membered N-heterocycle instead of a pyridine as chelating unit of the PYA ligand to provide less steric congestion for the rate-limiting transmetalation of the enolate.
View Article and Find Full Text PDFNature
January 2025
Department of Chemistry, The Scripps Research Institute, La Jolla, CA, USA.
C-H activation is the most direct way of functionalizing organic molecules. Many advances in this field still require specific directing groups to achieve the necessary activity and selectivity. Developing C-H activation reactions directed by native functional groups is essential for their broad application in synthesis.
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