Abstract
Application of carbon disulfide and dimethyl sulfate to 1, 4-dioxo-1, 2, 3, 4-tetrahydro-isoquinoline (I) in ammonia water gave methyl 1, 4-dioxo-1, 2, 3, 4-tetrahydroisoquinoline-3-dithiocarboxylate (II) which was further methylated with methyl iodide to 3-bis(methylthio)methylene-1, 4-dioxo-1, 2, 3, 4-tetrahydroisoquinoline (III). Application of alkyl bromoacetate to II, in the presence of potassium carbonate gave 1-alkoxycarbonyl-3-alkoxy-carbonylmethylthio-5-oxo-4H, 5H-thieno[3, 4-c]isoquinolines (IXa, b). II was also derived to dimethyl 6, 11-dioxo-1-methylthio-3, 4, 6, 11-tetrahydro[1, 4]thiazino[4, 3-b]isoquinoline-3, 4-dicarboxylate (X) by the action of dimethyl acetylenedicarboxylate. Treatment of II or III with phosphorus pentasulfide gave 3, 3, 4, 5-tetrahydro-1, 2-dithiolo[4, 3-c]isoquinoline-3, 5-dithione (XI), which the reaction of III with various amines afforded the corresponding amino derivatives (XIII, XIV, and XV). The reaction of III and sodium cyanide gave 3-cyano(methylthio)methylene-1, 4-dioxo-1, 2, 3, 4-tetrahydroisoquinoline (XVII) which reacted with hydrazine hydrate to from 3, 6-dioxo-4-methylthio-2, 3, 5, 6-tetrahydropyri- dazino[4, 3-c]isoquinoline (XVIII).
