High Fluorine Content Bis(fluoro‐Ponytailed) Bipyridine Palladium Complexes as Catalyst for Mizoroki‐Heck Reactions under Fluorous Biphasic Catalysis Conditions

Two highly fluorinated bipyridine derivatives, (4,4′‐bis(R_fCH₂OCH₂)‐2,2′‐bpy) {R_f = n‐C₁₀F₂₁ ( 1a ), n‐C₁₀F₂₃ ( 1b )}, have been synthesized starting from 4,4′‐bis(BrCH₂)‐2,2′‐bpy and the corresponding fluorinated alkoxides. The fluorine contents of ligands 1a‐b are 62.3% and 63.3%, respectively, both being white solids, virtually insoluble in CH₂Cl₂ or DMF and highly fluorophilic with a partition ratio between DMF and n‐C₈F₁₈ less than 1:1000. The reaction of ligands 1a‐b with [Pd(CH₃CN)₂Cl₂] results in novel Pd complexes [PdCl₂(4,4′‐bis‐(R_fCH₂OCH₂)‐2,2′‐bpy)] where R_f = n‐C₁₀F₂₁ ( 2a ), n‐C₁₀F₂₃ ( 2b ), respectively. The Pd complexes 2a‐b are pale yellow solids, soluble only in fluorinated solvents. The Pd complexes 2a‐b have been satisfactorily tested for Mizoroki‐Heck arylation under fluorous biphasic catalysis conditions in that the Pd complexes 2a‐b are easily recovered and maintain good catalytic activity after 8 consecutive cycles (> 90% yield). The TGA studies indicate that the Pd complexes 2a‐b are thermally stable up to 300 °C.