کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
1388388 982789 2011 11 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
The conformation of tetrafluorinated methyl galactoside anomers: crystallographic and NMR studies
موضوعات مرتبط
مهندسی و علوم پایه شیمی شیمی آلی
پیش نمایش صفحه اول مقاله
The conformation of tetrafluorinated methyl galactoside anomers: crystallographic and NMR studies
چکیده انگلیسی

The first single-crystal X-ray diffraction study of tetrafluorinated monosaccharide derivatives is presented. Both α- and β-methyl 2,3-dideoxy-2,2,3,3-tetrafluoro-d-galactopyranoside anomers adopt the 4C1 conformation. The values for the C1–O1 and C1–O5 bond lengths and the O5–C1–O1–CH3 dihedral angles are in line with what can be expected from the anomeric and exo-anomeric effects. The chair conformations are slightly distorted, presumably due to repulsion between 1,3-diaxial C–O and C–F bonds. The asymmetric unit of both compounds contains up to three independent molecules, which differ in the conformation of the hydroxymethyl group (including in one case a ‘forbidden’ gg rotamer). The molecular packing of the β-anomer shows a clear segregation between fluorinated and hydrophilic domains, while for the α-anomer the regions of fluorine segregation are broken by interleafing of OMe groups. There is one close OH⋯F contact, which is likely to arise from the crystal packing. NMR studies show that the two anomers also adopt a 4C1 conformation in solution (D2O, CDCl3).

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ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Carbohydrate Research - Volume 346, Issue 9, 1 July 2011, Pages 1129–1139
نویسندگان
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