Enantioselective protonation, delivery of a proton to a carbanion intermediate, is the most straightforward and fundamental method for the preparation of a chiral tertiary carbon stereocenter. Recent efforts for this objective have been realized through enamine catalysis, which has now become a prominent catalytic strategy enabling a range of fascinating chiral transformations. This review will summarize recent advances in the field of enantioselective enamine protonation for the synthesis of optically active carbonyl compounds. Dynamic kinetic resolutions of α-substituted carbonyl compounds through enamine intermediates will be discussed as well.
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http://dx.doi.org/10.1039/c7ob02615c | DOI Listing |
Chemistry
December 2024
Enamine Ltd., Winston Churchill Street 78, 02094, Kyїv, Ukraine.
A comprehensive study on the physicochemical properties of gem-fluorinated O-heterocyclic substituents is reported. Systematic additive effects of introducing O- and gem-CF group introduction on acidic properties (pK) of the corresponding carboxylic acids/protonated primary amines were demonstrated. The impact of the O/CF moieties on lipophilicity (LogP) was found to be complex; significant mutual influence of the corresponding polar moieties governed the compound's overall properties in this case.
View Article and Find Full Text PDFMolecules
August 2024
Department of Organic and Inorganic Chemistry, Faculty of Sciences, and IACYS-Green Chemistry and Sustainable Development Unit, University of Extremadura, 06006 Badajoz, Spain.
A curious and noticeable structural feature in Schiff bases from 2-aminoaldoses is the fact that imino tautomers arranged equatorially in the most stable ring conformation exhibit a counterintuitive reverse anomeric effect (RAE) in the mutarotational equilibrium, i.e., the most stable and abundant anomer is the equatorial one (β).
View Article and Find Full Text PDFJ Org Chem
September 2024
Key Lab of Colloid and Interface Chemistry, Ministry of Education, Institute of Theoretical Chemistry, School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, P. R. China.
Density functional theory calculations were conducted to refine our understanding at the molecular level of the synthesis of fused 1,2-dihydroquinolines through Rh- and acid-catalyzed skeleton-reorganizing coupling reactions of cycloheptatriene with amines. The results reveal that the reaction progresses via cascade catalysis, consisting of consecutive steps of Rh-catalyzed intermolecular coupling involving two Rh-Rh-Rh transformations with a maximum energy barrier of 27.1 kcal/mol, followed by acid-catalyzed intramolecular skeleton reorganization with a peak energy barrier of 23.
View Article and Find Full Text PDFNat Commun
August 2024
Center of Basic Molecular Science, Department of Chemistry, Tsinghua University, Beijing, China.
Electrochemical reactions via carbocation intermediates remain fundamental transformations that build up molecular functionality and complexity in a sustainable manner. Enantioselective control of such processes is a great challenge in a highly ionic electrolyte solution. Here, we report an anodic generation of chiral α-imino carbocation intermediates by enamine catalysis.
View Article and Find Full Text PDFActa Crystallogr E Crystallogr Commun
May 2024
Department of Chemistry, Taras Shevchenko National University of Kyiv, Volodymyrska str. 64/13, 01601 Kyiv, Ukraine.
The new palladium(II) complex, [Pd(CHNO)](CFCOO)·2CFCOOH, crystallizes in the triclinic space group with the asymmetric unit containing half the cation (Pd site symmetry ), one tri-fluoro-actetate anion and one co-crystallized tri-fluoro-acetic acid mol-ecule. Two neutral chelating 2-[5-(3,4,5-tri-meth-oxy-phen-yl)-4-1,2,4-triazol-3-yl]pyridine ligands coordinate to the Pd ion through the triazole-N and pyridine-N atoms in a distorted -PdN square-planar configuration [Pd-N 1.991 (2), 2.
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