Isopropyl 3-deoxy-α-D-ribo-hexopyranoside (isopropyl 3-deoxy-α-D-glucopyranoside): evaluating trends in structural parameters.

Isopropyl 3-de­oxy-α-d-ribo-hexo­pyran­oside (isopropyl 3-de­oxy-α-d-gluco­py­ran­oside), C9H18O5, (I), crystallizes from a methanol–ethyl acetate solvent mixture at room temperature in a 4C1 chair con­form­ation that is slightly dis­torted towards the C5SC1 twist-boat form. A com­parison of the structural parameters in (I), methyl α-d-gluco­pyran­oside, (II), α-d-gluco­pyranosyl-(1→4)-d-glucitol (maltitol), (III), and 3-de­oxy-α-d-ribo-hexo­pyran­ose (3-de­oxy-α-d-gluco­pyran­ose), (IV), shows that most endocyclic and exocyclic bond lengths, valence bond angles and torsion angles in the aldohexo­pyranosyl rings are more affected by anomeric configuration, aglycone structure and/or the con­form­ation of exocyclic substituents, such as hy­droxy­methyl groups, than by mono­deoxy­genation at C3. The structural effects observed in the crystal structures of (I)–(IV) were confirmed though density functional theory (DFT) calculations in com­puted structures (I)c–(IV)c. Exocyclic hy­droxy­methyl groups adopt the gauche–gauche (gg) con­form­ation (H5 anti to O6) in (I) and (III), and the gauche–trans (gt) con­form­ation (C4 anti to O6) in (II) and (IV). The O-glycoside linkage con­form­ations in (I) and (III) resemble those observed in disaccharides containing β-(1→4) linkages.