The synthesis of monomethoxy[1]benzothieno[2,3-c]quinolines

A series of monomethoxy[1]benzothieno[2,3-c]quinolines 24-28 were prepared by photocylization of the appropriate 3-chloro-N-phenylbenzo[b]thiophene-2-carboxamides 9–13 to [1]benzothieno[2,3-c]quinolin-6(5H)-ones 14-18 followed by chlorination to 6-chloro[1]benzothieno[2,3-c]quinolines 19-23 then dechlorination resulting in the title compounds except for 25 which was achieved by direct reduction of 15. Reaction of 24-28 with methyl iodide provided the corresponding N-methyl quaternary salts 29-33. Also, conversion of 4-meth-oxy[1]benzothieno[2,3-c]quinolin-6(5H)-one 16 to 4-methoxy-6-methylthio[1]benzothieno[2,3-c]quinoline 35 and 4,6-dimethoxy[1]benzothieno[2,3-c]quinoline 36 is described.