1H, 13C and 15N NMR, FT-IR as well as PM5 studies of a new Schiff base of gossypol with 3,6-dioxadecylamine in solution

The Schiff base of racemic gossypol with 3,6-dioxadecylamine (GSDN) has been synthesised and its structure has been studied by FT-IR, 1H, 13C and 15N NMR spectroscopy as well as by the PM5 semiempirical method. All spectroscopic methods have provided respective evidences that GSDN in solution exists exclusively in the enamine–enamine tautomeric form. The structure of the enamine–enamine tautomer is visualized and the hydrogen bonds stabilising this structure are discussed.