Chlorinated aromatic derivatives of cyclofructan 6 as HPLC chiral stationary phases

ABSTRACT

Cyclofructans (CF) are cyclic oligosaccharides consisting of a crown ether core with pendent fructofuranose units. These unique macrocycles were reported recently to be powerful chiral selectors. Derivatized and bonded to silica, CFs make excellent chiral selectors for HPLC. In this study, several new derivatives of cyclofructan 6 (CF6) were prepared by introducing aromatic moieties with electron-withdrawing chloro and nitro groups and an electron-donating methyl group. Their enantioselectivities were evaluated in the normal phase mode in comparison to the commercially available cyclofructan columns (LARIHC CF6-P, LARIHC CF6-RN, and LARIHC CF7-DMP). In several cases, the columns prepared in this work showed improved enantioselectivity over the existing commercially available stationary phases. Furthermore, an evaluation of the number and position of chloro and methyl groups on the phenyl substituents of CF6 is discussed in terms of their ability to alter enantioselectivity.

GRAPHICAL ABSTRACT

KEYWORDS:

• Atropoisomers
• chiral stationary phase
• chlorinated substituents
• cyclofructan
• enantioselectivity
• mechanism

Acknowledgments

Alain Berthod thanks the French National Center for Scientific Research ISA—CNRS-UMR5180 for continuous support.