Conformational analysis of methyl 2, 3, 4-tri-O-acetyl-6-deoxy-6-(R)-phenylsulfinyl-α-D-glucopyranoside (1), methyl 2, 3, 4-tri-O-acetyl-6-deoxy-6-(S)-phenylsulfinyl-α-D-glucopyranoside (2) and methyl 2, 3, 4-tri-O-acetyl-6-deoxy-6-phenylsulfonyl-α-D-glucopyranoside (3) in solution (CDCl₃) and the crystalline state was carried out using ¹H-NMR spectra and X-ray crystallographic data. The conformational preference of the C6-S bond in the above mentioned compounds was found to be GT (GT is short for gauche-trans), and as a 1 : 1 mixture of rotamers for the (S)-S-oxide (2) and sulfone (3) but not in the (R)-S-oxide (1) in the solid state.