Alkylation of 5-hydroxyisoquinoline (I) with bromide (II) in DMF at 80 C afforded isoquinolinium salt (III). This was reduced to tetrahydroisoquinoline (IV) by catalytic hydrogenation in the presence of Pd/C. Finally, Mannich reaction with formaldehyde and perhydroazepine (V) in THF-water at r.t. provided the target compound.