Collect. Czech. Chem. Commun.
2009, 74, 1151-1159
https://doi.org/10.1135/cccc2009067
Published online 2009-07-22 10:15:38
Organocatalysis with azahelicenes: the first use of helically chiral pyridine-based catalysts in the asymmetric acyl transfer reaction
Michal Šámala,b, Jiří Míšeka,b, Irena G. Staráa,b,* and Ivo Starýa,b,c,*
a Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
b Center for Biomolecules and Complex Molecular Systems, Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
c Department of Organic Chemistry, Charles University, Albertov 2030, 128 40 Prague 2, Czech Republic
Abstract
The successful utilisation of a helicene-based organocatalyst in acylative kinetic resolution of racemic secondary alcohol was described. Employing rac-1-phenylethanol, optically pure (–)-(M)-2-aza[6]helicene (5–20 mole %), isobutyric anhydride and N-ethyldiisopropylamine in chloroform at 22–40 °C, an asymmetric acyl transfer reaction took place overwhelming the uncatalysed background process. Moderate reactivity as well as selectivity factor (s = 9, 10) were observed. An effective control of the enantiodiscriminating step in acylative kinetic resolution by the helically chiral organocatalyst was proven for the first time.
Keywords: Azahelicenes; Organocatalysis; Asymmetric catalysis; Acyl transfer; Kinetic resolution.
References: 31 live references.
