solvent peak

water peak

Impurity peak

Terminal proton: δ4.3~6.0

Methyl 5C sugar

Other protons

When the dihedral angle is 90°, the coupling constant is 0; when the dihedral angle is 90°~180°, the coupling constant becomes larger as the angle increases; when the dihedral angle is 0°~90°, the coupling constant becomes larger as the angle increases. Increasing the coupling constant becomes smaller. In the pyran ring, when two adjacent protons are both a bonds, the dihedral angle is 180°, and the coupling constant is 6~8Hz; when one is an a bond and the other is an e bond, the dihedral angle is 60°, and the coupling constant is 60°. The constant is 2~4Hz

When the glycoside bond is of the β-D or α-L type, its terminal protons and H-2 are both a bonds, and the coupling constant is 6~8Hz; when the glycoside bond is of the β-L or α-D type, its terminal protons The matrix proton is an e bond and H-2 is an a bond. The coupling constant is 2~4Hz.

2-H sugar in the e bond: rhamnose, mannose, lyxose

-CH3: ~18; CH2OH: ~62; CHOH: 68~85; Terminal C: 95~105

The chemical shift of the terminal carbon is greater than 100: β-D, α-L of the C1 formula; α-D, β-L of the 1C formula; the chemical shift of the terminal carbon is less than 100: α-D, β-L of the C1 formula ; β-D, α-L of formula 1C

Coupling constants and glycoside bond configuration

concept

Change rules

Common 13C-NMR substituent displacement effects