Conformational analysis. Part 19—conformational analysis of 6‐deoxy‐6‐fluoro‐<scp>D</scp>‐glucose (6DFG) in solution

Abstract

Abstract The conformation of D‐glucopyranose and 6‐deoxy‐6‐fluoro‐D‐glucose (6DFG) in solution, as determined by 1 H and 19 F NMR, is reviewed. The 1 H NMR spectra of α‐ and β‐methyl D‐glucopyranosides and 6DFG in methanol, acetone, DMSO, and aqueous solution were acquired and fully analysed. A 19 F NMR spectrum of the methanol 6DFG solution, together with a 1 H COSY spectrum of α‐6DFG in methanol, were recorded. Accurate analyses of the ABC and ABCX spectra produced by the CHCH 2 OH and CHCH 2 F moieities, respectively, were performed, and from the vicinal J (H‐5,H‐6) coupling constants the populations of the three possible staggered rotamers about the C‐5C‐6 bond were calculated. The rotamer in which F is antiperiplanar to the ring O is particularly disfavoured, whereas the rotamer with F antiperiplanar to H‐5 is most favoured. This general trend was seen for both pyranose anomers in all four solvents.