Ring distortion in pyranosides caused by per-O-sulfation

Abstract

Distortion of the ring conformation in β-gluco- and β-xylopyranosides upon their per-O-sulfation was observed. In the case of glucose, a conformation intermediate between ^3,OB and ³S₁ was found, while complete ⁴C₁→¹C₄ inversion was detected in xylopyranoside. The conformational changes were evidenced experimentally by measuring intra-ring ¹H-¹H coupling constants and nuclear Overhauser effect (NOE) and were additionally confirmed by ab initio calculations.

Keywords: Conformation analysis; O-sulfation; Pyranoside; ab initio calculations.