The palladium-catalyzed cross-coupling reactions of (E)- or (Z)-1-fluorovinylstannanes with aryl iodides and vinyl iodides provide good yields of stereoisomerically pure substituted fluoroolefins with retention of the double bond geometry. The reaction takes place with copper(I) iodide present as a cocatalyst at ambient temperature or in refluxing tetrahydrofuran and is tolerant of a variety of functional groups. Highly functionalized and stereoisomerically pure monofluorovinyl ketones also were obtained under mild conditions by the coupling of 1-fluorovinylstannanes with acid chlorides. (1)H-{(19)F} NOE NMR experiments unequivocally established the stereochemistry of the coupling products E-14 and Z-14.
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http://dx.doi.org/10.1021/jo982200n | DOI Listing |
Molecules
December 2024
Science Institute, Chemistry Department, University of Iceland, Dunhaga 3, 107 Reykjavik, Iceland.
This report describes the asymmetric synthesis of a focused library of enantiopure structured triacylglycerols (TAGs) comprised of a single saturated fatty acid (C6, C8, C10, C12, C14 or C16), a pure bioactive n-3 polyunsaturated fatty acid (EPA or DHA) and a potent drug (ibuprofen or naproxen) intended as a novel type of prodrug. One of the terminal -1 or -3 positions of the glycerol backbone is occupied with a saturated fatty, the remaining one with a PUFA, and the drug entity is present in the -2 position. This was accomplished by a six-step chemoenzymatic approach starting from enantiopure ()- and ()-solketals.
View Article and Find Full Text PDFMolecules
December 2024
Faculty of Medicine, The John Paul II Catholic University of Lublin, Konstantynów 1J/4.03, 20-708 Lublin, Poland.
Improved methods for the synthesis of nicotine are of great importance due to the wide range of applications of synthetic nicotine, which is free from contamination with nitrosamines. Herein, we present a four-step chemical synthesis of ()-nicotine, involving the reduction in myosmine, enantiomeric separation of nornicotine, and subsequent methylation of the appropriate enantiomer of nornicotine obtained. The reduction in myosmine was investigated using both electrochemical and chemical approaches, achieving up to 90% yields of pure nornicotine.
View Article and Find Full Text PDFChemistry
November 2024
Department of Chemistry, Lomonosov Moscow State University, 119991, Leninskie gory 1 bld. 3, Moscow, Russia.
Two novel 1,10-phenanthroline-2,9-diamide ligands were constructed on the basis of 2-phenylpyrrolidine and obtained as pure diastereomers. These ligands demonstrated advanced properties in liquid-liquid extraction tests. They revealed high efficiency of americium(III) extraction alongside with the record values of selectivity in the separation of americium from light lanthanides from strongly acidic media.
View Article and Find Full Text PDFBiomed Chromatogr
January 2025
Univ. Lille, Inserm, Lille, France.
Int J Biol Macromol
December 2024
School of Pharmacy & School of Biological and Food Engineering, Changzhou University, Changzhou 213164, PR China. Electronic address:
Chiral (S)-o-fluorostyrene oxide (oFSO) and vicinal diol (R)-o-fluorophenylethane-1,2-diol (oFPED) are important intermediates for synthesizing treatments for neuropathic diseases. This study aimed to engineer Aspergillus usamii epoxide hydrolase (AuEH2) through a rational mutagenesis strategy to customize high enantioselectivity mutant for rac-oFSO. Out of 181 single-site mutants screened, six showed elevated enantiomeric ratio (E value) ranging from 32 to 108 according to E value and activity mutability landscapes.
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