| Abstract: | Gossypol was obtained as an yellow platelike crystal with m.p. 210-214 . In CDCl3 there were three tautomers of gossypol: Ⅰ aldehyde, Ⅱ lactol, Ⅲ ketal, in equilibrium .Their total 1H NMR spectra were assigned by means of 1D and 2D NMR techniques including 1H-1H cosy ,DEPT, HMQC (1H Detected Heteronuclear Multiple Quantum Coherence) and HMBC (1H Detected Heteronuclear Multiple Bond Connectivity) experiments.This paper first reported that we took use of the 2D NMR techniques to assign all of 1H NMR chemical shifts of each tautomer , through the assignments of each peaks we investigated the tautomerism of gossypol . We concluded that when gossypol ( Ⅰ ) was put into CDCl3 , it would tautomerized three tautomers, they stable existed and attained tautomeric equilibrium in a molar ratio of 6:2:1 according to peaks intensity ratios in CDCl3. The result listed in table 1.Table 1. The 1H spectroscopy chemical shifts (ppm) for gossypol (Ⅰ), (Ⅱ) and (Ⅲ)All spectra were recorded at room tempreture in CDCl3 using TMS as an internal standard reported in δ units,hydroxyl protons were identified by D2O exchange. |
