Electrophotocatalytic Thiocyanation and Sulfonylation Cyclization of Unactivated Alkenes

We report an electrophotocatalytic process that enables the thiocyanation and sulfonylation/cyclization of alkenes. It is applicable to a wide range of unactivated alkenes, using the inexpensive photocatalyst 2,4,6-triphenylpyrylium tetrafluoroborate (TPPT) to produce a diverse array of heterocycles containing sulfonyl and thiocyano groups with good functional group tolerance. The protocol operates under mild, chemical oxidant- and transition-metal-free, with a broad scope of substrates. Preliminary mechanistic studies suggest that the reaction involves a combination of electrolysis and the reductive quenching photocatalytic cycle of TPPT.