Structure of the adduct of Alantolactone with Z-L-Cys-L-Ala-OMe and 1H and 13C assignment of the Alantolactone moiety by 14 Tesla NMR

Analysis of the 'H-'H NOE effects observed for S-(11,13-dihydroalantolacton-13-yl)-~-cysteinyl-~-alanimnee thyl ester in (CD3),S0 at 14 T showed that the 7- and ll-protons are in cis positions. The distances between 7-, 8- and ll-protons of the adduct were derived by a semi-quantitative approach based on analysis of NOESY cross peaks and a computed molecular model. The simulated 'H spectrum of the alantolactone moiety is in excellent agreement with the experimental data. The complete assignments of the "C signals of alantolactone, its peptide adduct and four dipeptide precursors are based on one- and two-dimeusional 'H-% NMR techniques.