Collect. Czech. Chem. Commun.
2009, 74, 189-215
https://doi.org/10.1135/cccc2008180
Published online 2009-02-11 11:34:11
The quest for alternative routes to racemic and nonracemic azahelicene derivatives
Angelina Andronovaa,b, Florence Szydloa, Filip Teplýa, Miroslava Tobrmanováa, Amandine Volota, Irena G. Staráa,b,*, Ivo Starýa,b,*, Lubomír Rulíšeka,b, David Šamana, Josef Cvačkaa, Pavel Fiedlera and Pavel Vojtíšekc
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, 1 66 10 Prague 6, Czech Republic
c Department of Inorganic Chemistry, Charles University, Albertov 2030, 128 40 Prague 2, Czech Republic
Abstract
A series of diverse aromatic azadienetriyne and azatriynes was synthesised. These compounds were subjected to transition metal-mediated [2+2+2] cycloisomerisation to form pentacyclic or hexacyclic helically chiral azahelicene or azahelicene-like structures mostly in moderate yields. Introducing stereogenic centre(s) into selected azatriynes, cyclisation proceeded in a stereoselective fashion providing aza[5]helicenes or aza[6]helicene-like compounds in up to a 100:0 diastereomeric ratio. Gibbs energy differences between corresponding pairs of diastereomers (calculated at the DFT(B3LYP)/TZV+P level) were in good agreement with the experimental data and allowed for the prediction of the stereochemical outcome of the reaction. This study presents for the first time asymmetric synthesis of azahelicene derivatives in high optical purities.
Keywords: Alkynes; Arenes; Chirality; Cross-coupling; Helical structures; Azahelicenes; Pyridines; Helicity; DFT calculation; [2+2+2]cyclotrimerisation; Stereoselective synthesis.
References: 64 live references.
