Enantiomeric separation of new phytoalexin analogs with cyclofructan chiral stationary phases in normal‐phase mode

For the first time, three different derivatized cyclofructan chiral stationary phases were used for the direct high‐performance liquid chromatographic enantiomeric separation of 11 new racemic analogs of a natural indole phytoalexin. This class of compounds is known to have significant antiproliferative activity and other potentially useful pharmacological properties. The effect of various experimental factors was investigated to optimize the separations in the normal‐phase mode. It was found that the nature of polar modifier and additive in the mobile phase have significant impact on the enantioseparations. Better chiral recognition of analyzed compounds was achieved on (R)‐naphthylethyl carbamate cyclofructan 6 than on isopropyl carbamate cyclofructan 6 and dimethylphenyl carbamate cyclofructan 7. The thermodynamic parameters showed that the chiral separation was enthalpy controlled in all cases.