Chiral Separation of (R,S)-1,1′-Binaphthyl-2,2′-diyl Hydrogenphosphate by Capillary Electrophoresis Using Monosaccharides as Chiral Selectors

Abstract

Monosaccharides were investigated as chiral selectors in capillary electrophoresis of binaphthyl compounds. Among monosaccharides tested, glucose, mannose and their derivatives, except for methyl-β-d-glucopyranoside, were found to be effective for direct separation of racemic mixture of 1,1′-binaphthyl-2,2′-diyl hydrogenphosphate (BNP). d-Forms of galactose, sorbose, fructose, ribose, arabinose and xylose failed chiral separation of BNP. We tentatively concluded that monosaccharides (in the case of d-forms) must satisfy the following structural requirements for successful chiral separation of BNP enantiomers: (1) oxygen atom at C-1 is in α-configuration, (2) -OH group at C-4 is downward configurated and (3) the presence of a -CH²OH or -CH³ group at C-5. Thus, in the case of d-glucose, the chiral separation of BNP is anticipated to be achieved predominantly through the hydrogen bonding between oxygen atom at C-1 and hydrogen atom of -OH group at C-4 on D-glucose and hydrogenphosphate moiety of BNP.