Spectroscopic studies and PM5 semiempirical calculations of tautomeric forms of gossypol schiff base with (R)-tetrahydrofurfurylamine

A new Schiff base of gossypol with (R)-tetrahydrofurfurylamine (GSTF) was synthesised and its structure was studied by FT-IR, 1H NMR, 13C NMR, 15N NMR as well as PM5 semiempirical methods. It is shown that in the solution Schiff base exists in enamine–enamine tautomeric form. The structure of this tautomer is discussed in details. q 2004 Elsevier B.V. All rights reserved.