Activation of 1,1-difluoro-1-alkenes with a transition-metal complex: Palladium(II)-catalyzed Friedel-Crafts-type cyclization of 4,4-(difluorohomoallyl)arenes

Cationic palladium(II) ([Pd(MeCN)(4)](BF4)(2)) provides the first transition-metal-catalyzed method for electrophilic activation of electron-deficient 1,1-difluoro-1-alkenes, which allows their Friedel-Crafts-type cyclization with an intramolecular aryl group via a Wacker-type process. By using BF3 center dot OEt2, the cyclization was effected by a catalytic amount of the palladium without its reoxidation.