Total Synthesis of Phenanthroviridin Aglycon and Its Analog

We report the total synthesis of phenanthroviridin aglycon with interesting antibacterial and anticancer activities. A Pd‐catalyzed direct arylation of 5‐hydroxy‐1,4‐naphthoquinone with aryl iodides, which were prepared from 3,5‐dimethylphenol, gave aryl‐1,4‐naphthoquinones. Treatment of the resulting aryl‐1,4‐naphthoquinones with aqueous ammonia, followed by oxidative cyclization and deprotection, successfully yielded phenanthroviridin aglycon (1,8‐dihydroxy‐3‐methylbenzo[b]phenanthridine‐7,12‐dione) and its analog (1,11‐dihydroxy‐3‐methylbenzo[b]phenanthridine‐7,12‐dione). Phenanthroviridin aglycon, which has an ary‐1,4‐naphthoquinone skeleton, exhibits interesting antibacterial and anticancer activities. In this paper, we describe the total synthesis of phenanthroviridin aglycon and its analog utilizing the Pd‐catalyzed direct arylation of 5‐hydroxy‐1,4‐naphthoquinone with aryl iodide.