The α, α′-annelation of the enamine of 1,3-dihydro-2-phenalenone with methyl α-(bromomethyl)acrylate affords an aromatic bicyclic framework, methyl 8,9,10,11-tetrahydro-7,11-methano-12-keto-7H-cycloocta(de)-naphthalene-9-endo-carboxylate having the ester function positioned over the aromatic ring. The 9-exo-methyl-12, 12-dimethoxy ketal carboxylate anion derivative reacts with excess Br 2 in aqueous solution affording the bromo lactone epoxide derived through capture of the intermediate of electorphilic attack on the naphthalene ring, 12, 12-dimethoxy-2, 3-endo-epoxy-11a-endo-hydroxy-1-exo, 4-dibromo-7, 11-methano-9-methyl-11a, 1, 2, 3, 4, 8, 9, 10, 11-octahydro-7 H-cycloocta [de] naphthalene-9-endo-carboxylic acid δ lactone.