Abstract: The toxic meroterpenoid (-)-austalide B has been prepared in its natural form by chemical modification of the readily available optically active enedione 11. Following stereocontrolled Robinson annulation to give 13 and fully regiocontrolled gem-dimethylation of this intermediate, the highly functionalized tetracyclic ortho ester 22 was produced in four additional steps. At this point, it proved an easy matter to obtain 23 by Baeyer-Villiger ...
