Synthesis, enantioseparation, and absolute configuration assignment of iminoflavans by chiral high-performance liquid chromatography combined with online chiroptical detection.

Four racemic iminoflavan derivatives were synthesized by simple condensation at C-4 position of flavanone. All new compounds were characterized by using ultraviolet-visible, infrared, and nuclear magnetic resonance spectroscopic techniques. A chiral chromatographic analysis of racemic mixtures was performed by direct chiral high-performance liquid chromatography using Chiralcel® OD-H as chiral stationary phase, and online-coupled with electronic circular dichroism detector. The correlation of experimental electronic circular dichroism traces with quantum chemical electronic circular dichroism calculations run with time-dependent density functional theory made it possible to elucidate the absolute configuration for each enantiomer, and to establish the elution order.