Ring conformation Strong coupling effects rendering the ¹H-¹H coupling constants difficult.

• Intraresidue NOEs and ¹H-¹H coupling constants to determine relative axial/equatorial relationships and also stereochemistry of the anomeric position. Such determinations easy in rigid six-membered rings:
  • Strong NOE in 1,3-diaxial interactions.
  • Strong NOE and large J_HH for geminal and equatorial-equatorial systems.
  • Medium or small NOE and small J_HH for equatorial-axial systems.
  • Large J_HH and null NOE in axial-axial systems