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