Conoliferine and isoconoliferine, structurally novel alkaloid-lignan conjugates from Tabernaemontana corymbosa

Conoliferine and isoconoliferine were isolated from Tabernaemontana corymbosa as an unresolvable mixture of (1′S, 2′S)- and (1′R, 2′R)-diastereomers. These novel natural products are constituted from the union of an iboga alkaloid, ibogaine, and a lignan moiety, and represent the first instance of such an alkaloid-lignan conjugate. The structure was determined by spectroscopic methods, including the extensive use of NOE experiments for assignment of stereochemistry.