Treatment of 3,4-tetramethylene-6-amino-5-cyano-thiopyran-2(1H)thione (1) with alkali followed by acidification with HCl afforded 1,2,5,6,7,8-hexahydro-4-cyano-3(2H)-oxoisoquinoline-1-thiol (2). When compound (1) was reacted with excess alkyl halides the corresponding O- and S-alkylated isoquinolines (3) were obtained. Also, -chloroacetic acid and β-bromopropionic acid reacted with compound (2) to produce thiazolo and thiazinoisoquinoiines (4) and (5). Furthermore, the reaction of (2) with one mole of phenacylbromide produced-S-phenacyl derivatives (6), which cyclized to give the corresponding thiazoloisoquinoline (7). However two moles of phenacyl bromides gave the corresponding S- and O-phenacyl derivatives (8). The later compounds were cyclized to give furoisoquinoline derivative (9).