The biologically active conformation of ergot alkaloids

Summary Molecular mechanics and NMR studies of the D ring conformation of ergot alkaloids demonstrate that both D₁ and D₂ forms may exist in solution. The comparison of the geometric parameters defining the spatial relations between the aromatic moieties and the basic nitrogen of conformationally restricted dopamine analogs, and that of ergolene, shows the D₁ conformation to be the bioactive one.