Syntheses of Phosphonium Salts from Phosphines and Carbenium: Efficient CO2 Fixation and Phase‐Transfer Catalysts

A new library of phosphonium salts has been synthesized from the reaction of tris‐(2,6‐dimethoxyphenyl)carbenium with different phosphines. The resultant phosphoninum salts work as efficient phase‐transfer catalysts for the alkylation of 1,3‐dicarbonyl compounds. One compound, a bifunctional phosphonium salt prepared from tris‐(2,6‐dimethoxyphenyl)carbenium and an aminophosphine, was also found to be an efficient catalyst for CO2 fixation reactions with epoxides under mild conditions.