The synthesis of dimethoxy[1]benzothieno[2,3‐ c ]quinolines

A series of dimethoxy[1]benzothieno[2,3‐ c ]quinolines have been prepared by photocyclization of the appropriate N ‐phenyl‐3‐chlorobenzo[ b ]thiophene‐2‐carboxamides. The lactams obtained were converted into the thiolactams and their S ‐methyl derivatives. The lactams were also converted into the corresponding chloro derivatives which were catalytically dechlorinated into the dimethoxy[1]benzothieno[2,3‐ c ]quinolines. The latter compounds were converted into the N ‐methyl quaternary salts.