STRUCTURE OF THE ADDUCT OF ALANTOLACTONE WITH (Z)-L-CYS-ALA-OME - H-1AND C-13 ASSIGNMENT OF THE ALANTOLACTONE MOIETY BY NMR AT 14 T

Analysis of the H-1-H-1 NOE effects observed for 3-dihydroalantolacton -13-yl)-L-cysteinyl-L-alanine methyl ester in (CD3)(2)SO at 14 T showe d that the 7- and 11-protons are in cis positions. The distances betwe en 7-, 8- and 11-protons of the adduct were derived by a semi-quantita tive approach based on analysis of NOESY cross peaks and a computed mo lecular model. The simulated H-1 spectrum of the alantolactone moiety is in excellent agreement with the experimental data, The complete ass ignments of the C-13 signals of alantolactone, its peptide adduct and four dipeptide precursors are based on one- and two-dimensional H-1-C- 13 NMR techniques.