Endocrocin and related naturally occurring anthraquinone pigments like cinnalutein could be synthesized regioselectively via a Marschalk type reaction, starting from the natural hydroxy anthraquinone emodin. Furthermore, the new tri-O-methyl protected emodin-2- carbaldehyde may serve as a promising synthon for new bathochromically shifted, higher generation photodynamically active hypericin derivatives.
