Abstract
Solidβstate ^13^C{^1^H} crossβpolarization/magic angle spinning spectroscopy (CP/MAS) has been utilized to extract the molecular structure information of Taxol, which is an antiβtumor therapeutic medicine extracted from the yew bark. The ^13^C signals have chemical shift values quite consistent with those measured in solution phase, and the overall chemical shift range is over 200 ppm. Notably, most of the ^13^C resonances of the taxane ring have two clearly resolved spectral components except the resonance peaks of Cβ15, Cβ16 and Cβ17, which are located at the central part of the taxane ring. On the basis of our NMR data, we propose that these doublets originate from two slightly different molecular conformations of the taxane ring and still the central part of the ring remains structurally similar. Furthermore, it is demonstrated that the ^13^C chemical shift difference deduced from the doublet splittings can serve as a direct measure of the structural difference between the two conformations, which could possibly correlate with the antiβtumor activity of Taxol. Copyright Β© 2006 John Wiley & Sons, Ltd.