Synthesis of 1-Thio-Substituted Isoquinoline Derivatives by Tandem Cyclization of Isothiocyanates

A copper-catalyzed tandem arylation–cyclization process to access 1-(arylthio)isoquinolines from isothiocyanates and diaryliodonium salts is described. It is the first general method to construct the potentially useful 1-(arylthio)isoquinoline derivatives. Moreover, 1-(methylthio)isoquinoline derivatives were also achieved successfully with MeOTf instead of diaryliodonium salts under metal-free conditions. Mechanistic studies reveal that these two processes proceed in different routes. This method has been successfully applied to the synthesis of quinazolinone alkaloid rutaecarpine.