NMR studies of phakellins and isophakellins

Phakellins 3 and 4 and isophakellins 5 and 6 are tetracyclic pyrrole-imidazole alkaloids. Their structure elucidation is herein reviewed using state-of-the-art NMR methods. Special emphasis has been given to the application of ADEQUATE NMR Pulse sequence. Furthermore, N-15 NMR chemical shifts, proton T-1 relaxation times, and (1)J(CH) coupling constants were determined.