Total syntheses of diosindigo B, mamegakinone, biramentaceone, and rotundiquinone
Abstract
4-Methoxy-7-methylnaphthalene-1,5-diol, prepared via a new selective acetylation procedure, is oxidised by lead(IV) oxide to diosindigo B (Ia) which on further oxidation with nitric acid affords biramentaceone (IIa); related reactions produce mamegakinone (IIb) and rotundiquinone (IIc).