Alkyldisulfanium Salts: Isolable, Electrophilic Sulfur Reagents Competent for Polyene Cyclizations.

Tools that can effect electrophilic sulfur-promoted cation-π cyclizations are generally lacking, especially using alkylsulfide-based reagents. Herein we report that combining three different 1,2-dithioethers with Cl and SbCl generates isolable alkyldisulfanium salts that can effect such reactions. These new reagents can install -SMe, -SEt, and -SCHCHCF in modest, moderate, or good yield on diverse frameworks, including polyenes that terminate with electron-deficient groups. We also show that reagents such as dimethyl(methylthio)sulfonium tetrafluoroborate (DMTSF) can accomplish similar chemistry.