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.