Complete assignment of the 13 C NMR spectra of the ring forms of digitoxose by DEPT spectrum editing and two‐dimensional proton chemical shift correlation spectroscopy

The 13 C chemical shifts of the four isomeric ring forms of D‐digitoxose in dimethyl sulfoxide‐ d 6 solution have been assigned completely by DEPT 13 C NMR spectrum editing and two‐dimensional carbon–proton chemical shift correlation spectroscopy. The 13 C chemical shifts are discussed in terms of their dependence on ring size and on anomeric configuration. The equilibrated mixture of four ring forms of D‐digitoxose in dimethyl sulfoxide‐ d 6 solution has been analysed quantitatively by 13 C NMR spectroscopy, and the results compared with those obtained previously by 1 H NMR.