Synthesis and demethylation of new 5,6,7,8-tetrahydro-4,9-dimethoxy-1H-benz[f]indole

The title compound 17 was prepared in good yield starting from 5,6,7,8-tetrahydro-l-naphthol ( 9 ) by an advantageous synthesis route consisting of eight steps, as indicated in Scheme 2. Demethylation by reflux heating with anhydrous aluminium chloride in dry benzene furnished 4,9-dihydroxy- and 4,9-dioxo-5,6,7,8-tetrahydro-1H-benzf]indoles (compounds 18 and 19 , respectively). All new products were identified on the basis of spectral and analytical data.