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.