Conomicidines A and B, Unusual Alkaloid–Hydroxycinnamyl Alcohol Conjugates from Tabernaemontana corymbosa

Conomicidines A and B ( 1a and 2a , resp.) together with the diastereomeric isoconomicidines A and B ( 1b and 2b , resp.) were isolated from Tabernaemontana corymbosa as unresolvable mixtures of the (1′ S ,2′ S )‐ and (1′ R ,2′ R )‐diastereoisomers ( i.e. , 1a and 1b ; 2a and 2b ). These novel natural products are constituted from the union of an iboga alkaloid, ibogaine, and hydroxycinnamyl alcohol moieties, and represent the first examples of such alkaloid–hydroxycinnamyl alcohol conjugates. The structures were determined by spectroscopic methods, including the extensive use of NOE experiments for the assignment of the configuration.