Synthesis of tenuilobine, a bis-polyamine alkaloid from Oncinotis tenuiloba, and its transamidation to isotenuilobine

From the leaves of Oncinotis tenuiloba STAPF, a novel polyamine alkaloid, tenuilobine (9), was isolated. This paper presents the synthesis of 9, as well as the base-catalyzed Zip reaction of 9, leading to the transamidation product isotenuilobine (10). The structure of 10 was further confirmed by 2D-NMR correlation spectroscopy. For analytical purposes, the bis-polyamines 9 and 10 were converted into their pentaacetyl derivatives 12 and 11, respectively, which were readily separable by reverse-phase HPLC.