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The chiral 2-(pyridin-2-yl)imidazolin-5-one derivatives as efficient enantioselective catalysts for Henry reaction

Autoři: Drabina Pavel | Panov Illia | Karel Sergej | Jeništová Klára | Sedlák Miloš

Rok: 2012

Druh publikace: ostatní - přednáška nebo poster

Strana od-do: nestránkováno

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Jazyk	Název	Abstrakt	Klíčová slova
eng	The chiral 2-(pyridin-2-yl)imidazolin-5-one derivatives as efficient enantioselective catalysts for Henry reaction	The Henry reaction represents one of the basic processes in organic synthesis adopted in forming a carbon–carbon bond and is a key step in the synthesis of many significant compounds. The asymmetric variant of the Henry reaction plays a significant role in the synthesis of pharmaceutical precursors, in particular. The general procedure of this asymmetric synthesis requires the application of a suitable optically pure chiral ligand, often in combination with metal ions. In the case of the Henry reaction, complexes with Cu(II) have proven particularly useful. The optically pure substituted 2-(pyridin-2-yl)imidazolidine-5-ones were prepared and characterized. The absolute configurations of individual ligands were determined by X-ray analysis or NOESY experiments. The Cu(II) complexes of the respective ligands were studied as enantioselective catalysts of the nitroaldol (Henry) reaction of aldehydes, ketones and α-oxoesters with nitroalkane giving the corresponding substituted 2-nitroalkanols (Scheme 1). This type of catalytic system is significantly high enantioselective than early studied 2-(pyridin-2-yl)imidazolin-5-one derivatives. In the case of the derivatives with isopropyl group (R5 = iPr) high enantioselectivity was observed using ligands with anti-arrangement (up to 96% ee), however ligands with syn-arrangement are less enantioselective (up to 27% ee). On the other hand, the enantioselectivity of anti- and syn-arrangement of 2-(pyridin-2-yl)imidazolidine-5-ones with benzyl group (R5 = Bn) was found as similar (up to 91% ee).	chirality; 2-pyridin-2-ylimidazolin-5-one; enantioselectivity; catalyst; Henry reaction

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