Leadbeater et. al. reported the first example of transition-metal free Suzuki coupling reactions in 2003. The group later discovered that the Na2CO3 used for the reaction contained palladium contamination. The group subsequently published an updated procedure for the reaction to include parts-per-billion levels of palladium as a catalyst. In 2021 Xu et al. claimed that bis(otolyl)amine organocatalysts However, several groups independently reinvestigated their claims and found that the amine catalysts were contaminated with palladium complexes that were entrained during the chromatographic purification of the amine. The paper was retracted by the authors in 2021.