Chiral recognition of thiaheterohelicenes by alkyl beta-D-pyranoside micelles. Influence of extension of helix.
Chiral recognition of alkyl beta-D-pyranoside micelles toward [7] and [5] heterohelicenes possessing helical structures was investigated by 1H-NMR and CD (circular dichroism) spectroscopy. In dodecyl maltopyranoside micellar solution, P and M enantiomers of tetrathia[7]heterohelicene (7TH), which have rigid and stable helixes, manifested different chemical shifts in their 1H-NMR spectra due to differences in the diastereomeric interactions, implying that the micelles undergo stronger recognition toward the M enantiomer than the P enantiomer. On the other hand, in octyl glucopyranoside micellar solution, trithia[5]heterohelicene (5TH) and two kinds of its derivatives which are rapidly equilibrated between the enantiomers in solution, gave no distinctly resolved 1H-NMR peaks for either enantiomer even at a lowered temperature. However, these racemic [5]heterohelicenes in the micelles did develop induced CD absorptions owing to a displacement of the equilibrium, suggesting from the signs of their Cotton effects that the micelles prefer the M enantiomer to its antipode in conformity with the 1H-NMR results of 7TH.
Nakagawa
H
H
Faculty of Pharmaceutical Sciences, Josai University, Sakado, Saitama, Japan.
Gomi
K
K
Yamada
K
K
D002942:Circular Dichroism; D006571:Heterocyclic Compounds / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008823:Micelles; D015394:Molecular Structure; D011714:Pyrans / Q000737:chemistry*; D013237:Stereoisomerism
D006571:Heterocyclic Compounds; D008823:Micelles; D011714:Pyrans