Enantioselective complexation of chiral linear hosts containing monosaccharide moieties with chiral organic amines

Abstract

New chiral linear hosts ( 1– 3 , a : peracetylated derivatives, b : permethylated derivatives) containing monosaccharide end groups were designed on the basis of the structural features of permethylated 1 F-fructonystose (MeFruNys), which shows a remarkable chiral discrimination ability, and then synthesized. The chiral discrimination ability of their hosts toward chiral organic ammonium guests were evaluated using FAB mass spectrometry and 1H NMR. Their hosts showed chiral discrimination for some guests. As the contrasting compounds ( 4 and 5 ) hardly showed any chiral discrimination, it was clarified that the structural features extracted from MeFruNys are very significant factors for chiral recognition. The 1H NMR shift induced by adding a potassium ion (counter anion: SCN −) in (CD 3) 2CO suggested that the cation moiety of the chiral guests was located at the binding site consisting of the –O–C–C–O– units and the ring-oxygens of the saccharide moieties. The structure of the complex of host 1b with 1-(1-naphthyl)ethylammonium ion (NEA +) was estimated by the 1H NMR induced shifts and the molecular dynamics simulation.