Selenium-containing Heterocycles from Isoselenocyanates: Synthesis of 2-Arylaminoselenazolo[5,4-b]pyridines

The reaction of 3-amino-2-chloropyridine (4) with aryl isoselenocyanates (2a-d) in refluxing 2-propanol gave the hydrochlorides of 2-arylaminoselenazolo[5,4-b]pyridines (7a-d) in good yield. The free bases (8a-d) were obtained after treatment with aqueous NaOH and recrystallization. A reaction mechanism via the intermediate selenourea derivatives (5) is most likely. The structure of the 2-phenylamino derivative (8a) has been established by X-Ray crystallography