Optimization and Scale-Up of a Suzuki−Miyaura Coupling Reaction: Development of an Efficient Palladium Removal Technique

A ligand−solvent−base screen was performed on a Suzuki−Miyaura coupling reaction, and the screening data, followed by a set of focused experiments, helped to optimize reaction conditions. Further work was carried out that centered on reducing the level of residual palladium in the isolated product. Treatment of the reaction mixture with toluene and 20% aqueous NaHSO3 at elevated temperature lowered the palladium content from ∼8000 ppm to 100 ppm or less. The Suzuki−Miyaura coupling and palladium removal process were demonstrated on 20-L scale, are highly efficient and cost-effective, and require short cycle times.