Thiofunctionalization of Electron-Rich Heteroarenes Through Magnesiation and Trapping with Octasulfur

Herein we report a site-selective and thiol-free thiofunctionalization of electron-rich heteroarenes. After a selective ortho-magnesiation, the use of S-8 followed by an electrophile allows direct access to S-alkyl or -aryl derivatives. In situ oxidation provides the corresponding sulfoxide and sulfone derivatives. Applying this protocol, Cerlapirdine was prepared in 4 steps with 28% overall yield.