Matrine-type quinolizidine alkaloids (QAs) exhibit complex 1H NMR spectra due to overlapping signals from their CH2 and CH groups, which were crucial for elucidating their structures. Eu(FOD)3 was employed to resolve these overlaps and achieve complete NMR assignments using sophocarpine as a model. Optimal conditions were established by evaluating solvent, molar ratio, and field strength, successfully rendering all protons distinguishable and accurately assignable. This study demonstrates that shift reagents remain valuable for resolving resonance overlap in structurally related QAs.
Fu et al. (Fri,) studied this question.