Synthesis and silica-based immobilization of monofunctionalized cyclomaltoheptaose derivatives for enantioselective HPLC

Heptakis(6-O-tert-butyldimethylsilyl-2,3-di-O-methyl)cyclomaltohep taose (6-TBDMS-2,3-Me-beta-CD) and heptakis(2,3,6-tri-O-methyl)cyclomaltoheptaose (per-Me-beta-CD) were monofunctionalized by introduction of a 5-cyanopentyl group attached to one of the O-2, O-3 or O-6 positions and subsequent reduction with lithium aluminum hydride to give the corresponding mono-O-(omega-aminohexyl) derivatives. Alternatively, after attachment of a 7-octenyl group and further epoxidation the corresponding mono-omega-epoxyoctyl derivatives of 6-TBDMS-2,3-Me-beta-CD were obtained. The mono-O-(omega-aminohexyl) derivatives were immobilized by reaction with glycidoxypropyl and 'aldehyde' silica, whereas aminopropyl silica was used for the immobilization of the monoepoxyoctyl derivatives. The immobilized cyclodextrin derivatives were partially evaluated as chiral stationary phases in high-performance liquid chromatography (HPLC) and micro-HPLC.