Synthesis of the naphthalene portion of the rubromycins

reaction: see text]. A synthesis of a reduced version of the naphthazarin found in the rubromycin class of natural products is reported. The naphthalene ring system is formed via a D?tz reaction with a symmetrical alkyne. Differentiation between the C1' and C3' groups of the D?tz adduct is achieved by selective oxidation since the two methylene groups possess different oxidation potentials.