title: Peracetylated alpha-D-glucopyranosyl fluoride and peracetylated alpha-maltosyl fluoride.
abstract: The X-ray analyses of 2,3,4,6-tetra-O-acetyl-alpha-D-glucopyranosyl fluoride, C(14)H(19)FO(9), (I), and the corresponding maltose derivative 2,3,4,6-tetra-O-acetyl-alpha-D-glucopyranosyl-(1-->4)-2,3,6-tri-O-acetyl-alpha-D-glucopyranosyl fluoride, C(26)H(35)FO(17), (II), are reported. These add to the series of published alpha-glycosyl halide structures; those of the peracetylated alpha-glucosyl chloride [James & Hall (1969). Acta Cryst. A25, S196] and bromide [Takai, Watanabe, Hayashi & Watanabe (1976). Bull. Fac. Eng. Hokkaido Univ. 79, 101-109] have been reported already. In our structures, which have been determined at 140 K, the glycopyranosyl ring appears in a regular (4)C(1) chair conformation with all the substituents, except for the anomeric fluoride (which adopts an axial orientation), in equatorial positions. The observed bond lengths are consistent with a strong anomeric effect, viz. the C1-O5 (carbohydrate numbering) bond lengths are 1.381 (2) and 1.381 (3) A in (I) and (II), respectively, both significantly shorter than the C5-O5 bond lengths, viz. 1.448 (2) A in (I) and 1.444 (3) A in (II).
authors.affiliation: Department of Biological Chemistry, John Innes Centre, Colney Lane, Norwich NR4 7UH, England.
authors.forename: Simone
authors.initials: S
authors.lastname: Dedola
authors.forename: David L
authors.initials: DL
authors.lastname: Hughes
authors.forename: Robert A
authors.initials: RA
authors.lastname: Field
mesh_terms: D000107:Acetylation; D002236:Carbohydrate Conformation; D018360:Crystallography, X-Ray; D005947:Glucose / Q000031:analogs & derivatives* / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D008320:Maltose / Q000031:analogs & derivatives* / Q000737:chemistry; D008958:Models, Molecular; D015394:Molecular Structure; D013237:Stereoisomerism
chemical_list: C030364:glucosyl fluoride; C020395:alpha-maltosyl fluoride; D008320:Maltose; D005947:Glucose