The diterpene alkaloids: the structure and stereochemistry of heteratisine

Chemical and spectroscopic studies have shown that heteratisine (C22H33NO5), a diterpene lactone alkaloid occurring as a monobenzoyl ester in the roots of Aconitum heterophyllum Wall, has stereostructure 1. Heteratisine thus bears a closer structural relationship to the highly toxic and polyoxygenated alkaloids of the lycoctonine-aconitine type than to its companion bases of A. heterophyllum, atisine, atidine and hetisine. An unusual cleavage reaction occurring when 19-oxodehydroheteratisine (28) is treated with strong base is described.