Eosin Y, an organic dye, was activated as a photoredox catalyst in the presence of molecular oxygen using visible light and, when it was used in the reaction of aryl ketones and benzyl amines, afforded good yields (52-87%) of 2,4,6-triarylpyridines (21 examples) at ambient temperature. The aryl groups at the 2- and 6-positions are derived from ketones, while benzyl amine plays the dual role of providing an aryl functionality at the 4-position of pyridine as well as being a nitrogen donor.
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http://dx.doi.org/10.1021/acs.joc.6b00979 | DOI Listing |
J Am Chem Soc
January 2025
The Warren and Katharine Schlinger Laboratory for Chemistry and Chemical Engineering, Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States.
Ni-catalyzed asymmetric reductive cross-coupling reactions provide rapid and modular access to enantioenriched building blocks from simple electrophile precursors. Reductive coupling reactions that can diverge through a common organometallic intermediate to two distinct families of enantioenriched products are particularly versatile but underdeveloped. Here, we describe the development of a bis(oxazoline) ligand that enables the desymmetrization of -anhydrides.
View Article and Find Full Text PDFOrg Biomol Chem
January 2025
Department of Chemistry, Indian Institute of Technology Roorkee, Roorkee-247667, Uttarakhand, India.
Ni(II)-hydrazineylpyridine (Ni(II)-PyH)-catalyzed regioselective synthesis of α-benzyl substituted β-hydroxy ketones from α,β-unsaturated ketones and alcohols is reported a Fenton free-radical reaction. This protocol enables facile access to desired products in good to excellent yields in 12 h using toluene solvent at room temperature to 100 °C. The structural analysis of the products was confirmed by H, C-NMR, GC-MS, and HRMS data.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
January 2025
Department of Chemistry, University of Oxford, Chemistry Research Laboratory, Mansfield Road, Oxford, OX1 3TA, UK.
Compounds containing quaternary stereocentres are a valuable motif in biologically active compounds. Herein we present our strategy to utilise the hydrogen borrowing manifold to access α-quaternary ketones via a tandem acceptorless dehydrogenation-cyclisation cascade. This new application of the methodology results in the formation of five- and six-membered carbocycles with a high degree of diastereoselectivity.
View Article and Find Full Text PDFMolecules
December 2024
School of Chemistry and Physics, University of KwaZulu-Natal, Scottsville, Pietermaritzburg 3209, South Africa.
Benzylic C-H oxidation to form carbonyl compounds, such as ketones, is a fundamental transformation in organic synthesis as it allows for the preparation of versatile intermediates. In this review, we highlight the synthesis of aromatic ketones via catalytic, electrochemical, and photochemical oxidation of alkylarenes using different catalysts and oxidants in the past 5 years. Additionally, we also discuss the synthesis of heterocyclic molecules using benzylic C-H oxidation as a key step.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
December 2024
School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing, China.
Suppressing over-oxidation is a crucial challenge for various chemical intermediate synthesis in heterogeneous catalysis. The distribution of oxidative species and the substrate coverage, governed by the direction of electron transfer, are believed to influence the oxidation extent. In this study, we presented an experimental realization of surface coverage modulation on a photoelectrode using a photo-induced charge activation method.
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