Studien zur Synthese einer Modellverbindung für Tolyporphin K

Since the isolation of Tolyporphin A from the pacific cyanobacterium Tolypothrix nodosa in 1992, ten further Tolyporphins named B to K have been identified. Whereas Tolyporphins A-J belong to the bacteriochlorin structural class, Tolyporphin K is the only chlorin among these natural products. These compounds deserve special interest because of their biological activity. Tolyporphins are multidrug resistance (MDR) reversal agents and show a potent photosensitizing activity against tumor cells.The aim of this work is the total synthesis of a model compound for Tolyporphin K. In our synthetic approach two routes (I and II) were envisaged based on four different building blocks A, B, C and D. The key difference between route I and II is the sequential order in which the monocyclic rings are linked together.The route I succesfully led to a tetracyclic compound, advanced precursor of Tolyporphin K.