Selenium‐Containing Heterocycles from Isoselenocyanates: Synthesis of 1H‐5‐Selena‐1,3,6‐triazaaceanthrylene Derivatives

The reaction of aryl isoselenocyanates 8 with methyl 3‐amino‐4‐chloro‐1‐ethylpyrrolo3,2‐c]quinoline‐2‐carboxylate ( 6 ) in boiling pyridine leads to tetracyclic selenaheterocycles of type 9 in high yield (Scheme 3). A reaction mechanism via an intermediate selenoureido derivative A and cyclization via nucleophilic substitution of Cl by Se is proposed (Schemes 3 and 5). The reaction of 6 with 4‐bromophenyl isothiocyanate yields the analogous thiaheterocycle 12 (Scheme 4). The molecular structures of 9c and 12 have been established by X‐ray crystallography.