Chirality sensing of saccharides using a boronic acid-appended chiral ferrocene derivative

A diboronic acid-appended chiral ferrocene derivative (R)-9 was designed and synthesized. This chiral ferrocene scaffold was obtained by resolution of the diastereomer with a monosaccharide derivative. One can therefore expect that (R)-9 would show D/L selectivity for specific monosaccharides. The complex formation of (R)-9 with Various saccharides using the two boronic acid functions was conveniently monitored by a change in the circular dichroism (CD) spectra. The CD spectral change (Delta[theta]) induced by added monosaccharides was chiroselective: in particular, D/L-alloses and D/L-galactoses induced the 8.0- and 7.0-fold difference in the magnitude of the CD spectral change. The association constants for D- and L-saccharides (K-D and K-L, respectively) were determined: among them, (R)-9 showed a significant discrimination ability for mannose (K-L/K-D = 2.6) and arabinose (K-L/K-D = 1/2.4). The origin of D/L selectivity was discussed on the basis of computational studies on (R)-9 saccharide complexes. (C) 2000 Elsevier Science Ltd. All rights reserved.