Of the five widely distributed structural pigments of the sea urchins (echinoids) one (spinochrome B) is a derivative of juglone, while four (spinochromes A, C, D, and E) are derivatives of naphthazarin. In addition to the two peri OH groups of naphthazarin these compounds bear one or more β-hydroxyls and/or an acetyl side chain. The synthesis of these four naphthazarin derivatives is described. The naphthalene skeleton was ...
