Synthesis of Stentorin.

Abstract

The two isomeric structures (2) and (3) proposed for the photodynamic pigment stentorin have both been synthesized for the first time, thereby allowing unambiguous identification of the natural material as (2). Synthesis of these highly condensed aromatic systems involved controlled oxidative couplings of the new anthrones (7) and (8), each synthesized by regiocontrolled cycloaddition.