Palladium-catalyzed cross-coupling reactions are used in many organic syntheses and the development of new catalytic systems is always on-going. Development of an efficient catalytic system requires costly and time-consuming trial and error for the optimization of numerous variables, including catalyst, ligand, base, additive, solvent, stoichiometry, and temperature.

Sunwoo Lee and co-workers, Chonnam National University, Republic of Korea, have employed high-throughput screening assays, originally developed to streamline the pharmaceutical discovery process, to speed up catalyst optimization. The colormetric assays use gold nanoparticles to sense the iodide ions released on completion of the cross-coupling of aryl iodides. This gives a non-substrate-specific way to determine the extent of the reaction and significantly reduces the time to identify promising leads.

• A Colorimetric High-Throughput Screening Method for Palladium-Catalyzed Coupling Reactions of Aryl Iodides Using a Gold Nanoparticle-Based Iodide-Selective Probe
  E. Jung, S. Kim, Y. Kim, S. H. Seo, S. S. Lee, M. S. Han, S. Lee,
  Angew. Chem. Int. Ed. 2011.
  DOI: 10.1002/anie.201100378