Browsing by Author "Pietrusiewicz, Kazimierz Michał"

Now showing 1 - 6 of 6
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    A General Phenomenon of Spontaneous Amplification of Optical Purity under Achiral Chromatographic Conditions
    (MDPI, 2019) Demchuk, Oleg M.; Pietrusiewicz, Kazimierz Michał; Borkowski, Mariusz; Strzelecka, Dorota; Kielar, Katarzyna; Kicińska, Wioleta; Karevych, Sergei; Jasiński, Radomir
    This work explores the behavior of chiral compound mixtures enriched in one of the enantiomers whilst a typical chromatography on the achiral stationary phase is employed. The influence of several factors, such as the eluent composition, ratio of the compound to the stationary phase, and the initial enatiomeric purity of the compound used on the distribution of the enantiomers in the collected chromatographic fraction, was studied. The obtained results indicate that the phenomenon of Self Disproportionation of Enantiomer (SDE) occurred in all cases, and some of the collected fractions got higher optical purities than the initial one. Thus, achiral column chromatography could be applied in some cases as the simplest approach for chiral purification. Based on the experimental results and DFT calculations, an alternative concept explaining the SDE phenomenon was proposed. Due to its generality and simplicity, SDE may also be responsible for the formation of the first chiral non-racemic compounds on the early Earth.
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    Efficient Oxidative Resolution of 1-Phenylphosphol-2-Ene and Diels–Alder Synthesis of Enantiopure Bicyclic and Tricyclic P-Stereogenic C-P Heterocycles
    (MDPI, 2020) Demchuk, Oleg M.; Pietrusiewicz, Kazimierz Michał; Koprowski, Marek; Drzazga, Zbigniew; Parcheta, Renata; Łastawiecka, Elżbieta; Justyniak, Iwona
    1-Phenylphosphol-2-ene 1-oxide is effectively resolved by L-menthyl bromoacetate to afford both SP and RP enantiomers of 1-phenylphosphol-2-ene 1-oxide on a multigram scale. The resolved 1-phenylphosphol-2-ene oxide has been found to undergo face-selective and endo-selective cycloadditions with a series of acyclic and cyclic dienes to produce enantiopure P-stereogenic C-P heterocycles of hexahydrophosphindole and hexahydrobenzophosphindole as well as phospha[5.2.1.02,6]decene and phospha[5.2.2.02,6]undecene structures. Conversions of these cycloadducts to the fully saturated heterocyclic systems as well as to their P (III), P = S, P = Se and P-BH3 derivatives have been demonstrated to occur with retention of configuration and preservation of configurational homogeneity at P. A perplexing case of stereomutation at P during reduction of a tricyclic β-hydroxy phosphine oxide by PhSiH3 at 80 °C has been recorded.
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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 Insights into the Mechanism of Reduction of Tertiary Phosphine Oxides by Means of Phenylsilane
    (Wiley-Blackwell, 2015) Demchuk, Oleg M.; Jasiński, Radomir; Pietrusiewicz, Kazimierz Michał
    The mechanism of the reduction of phosphine oxides by PhSiH3 was established on the basis of kinetic measurements and Density Functional Theory (DFT) calculations. In particular, it has been proved that the model reaction between tri-n-butylphosphine oxide and phenylsilane occurs via a nonpolar mechanism. The data presented herein allow prediction and verification of the applicability of the new reduction reagents and conditions for industrially attractive processes.
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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.
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    Rational design of novel ligands for environmentally benign cross-coupling reactions
    (Walter de Gruyter, 2011) Demchuk, Oleg M.; Kielar, Katarzyna; Pietrusiewicz, Kazimierz Michał
    Transition-metal (TM) complexes of new phosphines, readily prepared by a straight forward three-step modular synthesis, were successfully employed in difficult crosscoupling reactions conducted under mild conditions (water, “open-flask”, low temperature) that aspire to meet green chemistry criteria. High yielding catalyzed by bismuth or rhodium complexes oxidative arylation of naphthoquinone gave the key 2-arylnaphthoquinone intermediates for facile bismuth triflate-catalyzed Michael addition of secondary phosphine oxides. Subsequent O-methylation and reductions of the resulting products gave access to the target air-stable phosphine ligands in good overall yields (up to 60 %).