Synthesis and characterization of 4,6-O-butylidene-N-(2-hydroxybenzylidene)-β-D-glucopyranosylamine: crystal structures of 4,6-O-butylidene-α-d-glucopyranose, 4,6-O-butylidene-β-D-glucopyranosylamine and 4,6-O-butylidene-N-(2-hydroxybenzylidene)-β-D-glucopyranosylamine

Abstract

4,6-O-Butylidene-N-(2-hydroxybenzylidene)-β-D-glucopyranosylamine was synthesized and characterized using analytical, spectral and single-crystal X-ray diffraction methods. ¹H and ¹³C NMR studies showed the presence of the β-anomer, which has also been confirmed by the crystal structure. The molecular structure of this compound showed the presence of the tridentate ONO ligation-core. Both precursors, 4,6-O-butylidene-α-D-glucopyranose and 4,6-O-butylidene-β-D-glucopyranosylamine were characterized using single crystal X-ray diffraction. The α-anomeric nature of the former and β-anomeric nature of the latter were proposed based on ¹H NMR studies and were confirmed by determining the crystal structures. In addition, the crystal structure of 4,6-O-butylidene-β-D-glucopyranosylamine revealed the C-1-N-glycosylation. In all the three molecules, the saccharide unit exhibits a ⁴C₁ chair conformation. In the lattice, the molecules are connected by hydrogen-bond interactions. The conformation of 4,6-O-butylidene-N-(2-hydroxybenzylidene)-β-D-glucopyranosylamine is stabilized via an O-H···N intramolecular interaction, and each molecule in the lattice interacts with three neighboring molecules through hydrogen bonds of the type O-H···O and C-H···O.