Syntheses of Arylphosphonium Salts from Cyclotrimerization of Terminal Aryl Alknyes by a Ruthenium Pentadienyl Complex and Revisiting the Catalytic Dimerization

The synthesis of polyaryl phosphonium salts by cyclotrimerization of aryl alkynes is induced by a stoichiometric amount of the ruthenium η5-pentadienyl complex (η5-C5H7)­(PPh3)2RuCl (1). With only 1 mol % quantity, complex 1 efficiently catalyzed the dimerization of aryl alkynes at room temperature to afford the corresponding (Z)-1,4-diarylbut-1-en-3-yne derivatives as the major products.