The photodynamic pigment stentorin (1), isolated from the protozoan Stentor coeruleus, is one of the longest known natural products having a perylenequinone skeleton. As a related family of this pigment, hypericin (2) and blepharismins (3) are also known. Due to their characteristic structure and interesting biological activity including anti-HIV activity, these compounds have attracted a considerable attention from organic as well as synthetic chemists. In our own efforts directed toward the total synthesis of stentorin, we have developed new synthetic methods: 1. A new practical method for the regioselective nucleophilic aromatic alkylation of p-methoxy-substituted benzoic esters with Grignard reagents, 2. An efficient construction of an anthraquinone key intermediate based on the coupling between 5 and 6, followed by intramolecular Friedel-Crafts acylation and oxidation, and 3. Construction of perylene derivative 19 via the oxidative coupling of anthracene 18 using FeCl_3. The final step for the conversion of 19 to 1 is now underway.
