Cyclofructans, a new class of chiral stationary phases

Abstract

Cyclofructans are cyclic oligosaccharides consisting of β-2,1 linked d-fructofuranosefructofuranose units. Although known for more than 20 years, they were only recently proposed as powerful chiral selectors after alkylation or aryl derivatization. The mechanism of chiral recognition of derived cyclofructan cyclofructose is investigated. A structural comparison of the 18-crown-6 ether and the cyclofructans with six fructofuranose units (CF6) and the derivatized CF6 is made taking into account the similarities between the internal ether macrocycles. Clear differences are seen that offer possible explanations for the very different enantioselectivities of the three selectors. The structural modification brought by the alkyl derivation of CF6 allows for a remarkable enantiorecognition of all native chiral amines. Aryl-derivatized CF6 are less selective for amines but have a broad enantiorecognition for other classes of enantiomers. This new type of chiral selector has a high loading potential, allowing it to purify large amounts of materials. © 2010 Springer-Verlag Berlin Heidelberg.