Permanganate oxidation of 12-chloro-5, 6, 7, 7a-tetrahydro-2, 3, 9, 10-tetramethoxy-7-methylindeno [2, 1-α] [3] benzazepine (5) in the presence of piperidine gave the diketospirobenzylisoquinoline (11) and the lactone (15), the latter of which was converted into erythro-and threo-phthalideisoquinoline (16 and 17). 2, 3-Dihydro-7, 8-dimethoxy-5-(2, 3-dimethoxybenzoyl)-3-methyl-1H-3-benzazepine (4) was prepared from N-β-(3, 4-dimethoxyphenethyl)-2, 3-dimethoxyphenylacetamide (26) in four steps.