A Convenient Synthesis of Fluorobenzaldehydes by KF/Ph4PBr/18-Crown-6 Reagent System
4-Fluorobenzaldehyde was easily synthesized from 4-chlorobenzaldehyde by potassium fluoride in the presence of tetraphenylphosphonium halide plus 18-crown-6 or poly(ethylene glycol) dimethyl ether. Several fluorobenzaldehyde derivatives were similarly prepared from the corresponding chloro-derivatives in good yields.