Browsing by Author "Szwaczko, Katarzyna"

Now showing 1 - 2 of 2
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    Metathetic approach to new NORPHOS-related bisphosphanes: facile synthesis and application in asymmetric hydrogenation
    (Walter de Gruyter, 2021) Demchuk, Oleg M.; Szwaczko, Katarzyna; Mirosław, Barbara; Wójciuk, Grzegorz; Mazur, Liliana; Pietrusiewicz, Kazimierz Michał
    A highly efficient synthesis of new chiral bisphosphanes derived from the renowned NORPHOS ligand is presented. The synthesis involves ring-opening metathesis of NORPHOS dioxide with an external olefin, followed by saturation of the new double bonds and adjustment of the oxidation level of phosphorus centers oxidation level. The synthesized bisphosphanes retain the configuration and enantiomeric purity of the starting NORPHOS. Their utility as ligands in asymmetric catalysis is exemplified using an open-NORPHOS ligand in some benchmark Rh-catalyzed hydrogenations of enamides where excellent chemical yields and enantiomeric purities of the products have been secured. The proposed protocol demonstrated the possibility of a straightforward synthesis of new chiral catalysts to be utilized in the asymmetric synthesis of pharmaceutically important compounds, such as amino acid derivatives.
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    New Rigid Polycyclic Bis(phosphane) for Asymmetric Catalysis
    (MDPI, 2019) Demchuk, Oleg M.; Pietrusiewicz, Kazimierz Michał; Szwaczko, Katarzyna; Mirosław, Barbara; Dybała, Izabela; Jasiński, Radomir
    A simple, highly efficient synthesis of a series of novel chiral non-racemic rigid tetracyclic phosphorus ligands, applicable in important chemical asymmetric transformations, was performed. In a tandem cross-coupling/C-H bond activation reaction, a well-recognised and readily available ligand (R,R)-NORPHOS was used as the starting material. The palladium complexes of new ligands were obtained and characterised on the example of a crystalline dichloropalladium complex of [(1R,2R,9S,10S,11R,12R)-4-phenyltetracyclo[8.2.1.02,9.03,8]trideca-3,5,7-triene-11,12-diyl]bis(diphenylphosphane). A notably high activity and stereoselectivity of the palladium catalysts based on the new ligands were confirmed in a model asymmetric allylic substitution reaction. Herein, we discuss the geometry of the palladium complexes formed and its impact on the efficiency of the catalysts. A comparison of their geometric features with other bis(phosphane) ligand complexes found in the Cambridge Structural Database and built density functional theory (DFT) commutated models is also presented and rationalised.