The authors report the isolation of conomicidines A and B and isoconomicidines A and B from Tabernaemontana corymbosa as unresolvable diastereomeric mixtures. They identify these as the first known alkaloid–hydroxycinnamyl alcohol conjugates, each formed from ibogaine and a hydroxycinnamyl alcohol moiety, with structures and configurations assigned by spectroscopy including NOE experiments.
Abstract
Abstract 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.