A General Approach to Angucyclines: Synthesis of Hatomarubigin A, Rubiginone B2, Antibiotic X-1488E, 6-Hydroxytetrangulol, and Tetrangulol

Hatomarubigin A was prepared in 41% yield in a single procedure from acyl naphthoquinone 15 and 5-methylcyclohexane-1,3-dione (16). The net reaction consists of Michael addition to an acyl quinone followed by intramolecular aldol condensation. Hatomarubigin A then served as a common intermediate in syntheses of the angucyclinone antibiotics rubiginone B2, antibiotic X-1488E, 6-hydroxytetrangulol, and tetrangulol.