First total synthesis of the 7,6′-coupled antifungal naphthylisoquinoline alkaloid dioncophylline B

The first total synthesis of the antimalarial alkaloid dioncophylline B (2) from Triphyophyllum peltatum (Dioncophyllaceae), and thus the first preparation of a 7,6′-coupled naphthylisoquinoline, is described. Key steps within this synthesis are the ortho-functionalization of the MOM-protected naphthalene and isoquinoline moieties 14 and 7 by directed ortho-metalation, with subsequent stannylation of the naphthalene part and bromination of the isoquinoline portion, and the regioselective intermolecular Stille coupling reaction of these building blocks. The presented synthesis opens the way for the preparation of further 7-coupled compounds of this class of alkaloids.