The palladium-catalyzed aerobic oxidation of alkenes and especially styrenes (Wacker oxidation) by using chiral pseudo C(2)-symmetrical bis(isonitrile) ligands in the absence of further cocatalysts gives rise to methyl ketones in a highly chemoselective manner. The palladium bis(isonitrile) catalyst was characterized by NMR spectroscopy and X-ray structure analysis, revealing a dissymmetric coordination of palladium by the two isonitrile moieties.
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http://dx.doi.org/10.1002/chem.200901560 | DOI Listing |
J Am Chem Soc
December 2024
Institute for Organic Chemistry, University of Regensburg, 93053 Regensburg, Germany.
Diarylmethanes play, in part, a pivotal role in the design of highly potent, chiral, nonracemic drugs whose bioactivity is typically affected by the substitution pattern of their arene units. In this context, certain arenes such as -substituted benzenes or unsubstituted heteroarenes cause particular synthetic challenges, since such isosteric residues at the central methane carbon atom are typically indistinguishable for a chiral catalyst. Hence, the stereoselective incorporation of isosteric (hetero)arenes into chiral methane scaffolds requires the use of stoichiometrically differentiated building blocks, which is typically realized through preceding redox-modifying operations such as metalation or halogenation and thus associated with disadvantageous step- and redox-economic traits.
View Article and Find Full Text PDFThe utilization of Pd(ii)-catalyzed oxidation for the transformation of terminal olefins into methyl ketones has emerged as a particularly intriguing and versatile strategy in organic synthesis. Herein we report a novel Pd(ii)-catalyzed Wacker-type oxidation with covalent bidentate ligands. The ligand, 1-(pyridin-2-yl)-1,2-dihydro-3-indazol-3-one, exhibits excellent performance in converting olefins to ketones.
View Article and Find Full Text PDFChemistry
November 2024
Department of Chemistry, Indian Institute of Technology Guwahati, Assam, 781039, India.
The first catalytic enantioselective intramolecular allylic dearomatization of allylic alcohol tethered α- and β-naphthols has been developed with iridium/acid-dual catalysis. A wide range of polycyclic spiroketones containing vicinal tertiary and quaternary carbon stereocenters were readily prepared in good to high yields with high diastereo- and moderate to excellent enantioselectivities. An unusual anti-Markovnikov Wacker oxidation has also been shown in synthetic transformations.
View Article and Find Full Text PDFJ Am Chem Soc
November 2024
Laboratory of Synthesis and Natural Products (LSPN), Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL-SB-ISIC-LSPN), BCH5304, CH-1015 Lausanne, Switzerland.
J Am Chem Soc
October 2024
Key Laboratory of Advanced Energy Materials Chemistry of Ministry of Education, College of Chemistry, Nankai University, Tianjin 300071, P. R. China.
The selective oxidation of olefins by molecular oxygen holds great importance in the chemical industry due to its remarkable adaptability in constructing carbonyl compounds. Classical homogeneous Wacker oxidation with a complex system of PdCl-CuCl-HO is currently employed in the industrial production of acetaldehyde, which suffers from several key drawbacks. The development of alternative heterogeneous catalytic systems for Wacker-type oxidations has been hotly pursued for decades.
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