Photoredox Catalytic Pentafluorosulfanylative Domino Cyclization Of Alpha-Substituted Alkenes To Oxaheterocycles By Using Sf6

Virtually inert sulfur hexafluoride becomes a precious pentafluorosulfanylation agent, if properly activated by photoredox catalysis, to access alpha-fluoro and alpha-alkoxy SF5-compounds. This advanced protocol converts SF6 in the presence of alkynols as bifunctional C-C- and C-O-bond forming reagents directly into pentafluorosulfanylated oxygen-containing heterocycles in a single step from alpha-substituted alkenes. The proposed mechanism is supported by theoretical calculations and gives insights not only in the pentafluorosulfanylation step but also into formation of the carbon-carbon bond and is in full agreement with Baldwin's cyclization rules. The key step is a radical type 5-, 6- respectively 7-exo-dig-cyclization. The synthesized oxaheterocycles cannot be simply prepared by other synthetic methods, show a high level of structural complexity and significantly expand the scope of pentafluorosulfanylated building blocks valuable for medicinal and material chemistry.