Synthesis of Tetraarylphosphonium Salts from Triarylphosphines and Aryl Bromides Exploiting Light and Palladium

We herein report that an onium salt-forming reaction of triarylphosphines with aryl bromides is promoted by the sequential cooperation of light with palladium. The mild reaction conditions tolerate various functionalities such as amino and hydroxy groups, and thus, the present method offers a convenient and expedient access to variously substituted tetraarylphosphonium salts. An onium salt-forming reaction of triarylphosphines with aryl bromides is promoted by the sequential cooperation of light with palladium. The mild reaction conditions tolerate various functionalities such as amino and hydroxy groups, and thus, the present method offers a convenient and expedient access to variously-substituted tetraarylphosphonium salts.