Amitorines A and B, Nitrogenous Diterpene Metabolites of <i>Theonella swinhoei</i>: Isolation, Structure Elucidation, and Asymmetric Synthesis

Two new nitrogenous prenylbisabolanes never before found in Lithistid sponges have been isolated from <i>Theonella swinhoei</i>. These new diterpenes, named amitorine A (<b>1</b>) and amitorine B (<b>2</b>), containing a prenylbisabolane skeleton have been characterized by spectroscopic analyses, and the relative and absolute configurations of <b>1</b> and <b>2</b> were determined by asymmetric synthesis of both diastereomers via the common bicyclic lactone <b>6</b> intermediate