page_title: PEPPSI
section_title: Properties and applications
hierarchical_section_title: PEPPSI / Properties and applications
caption_attribution_description: English: Sonogashira reaction catalyzed with iPEPPSI complex.
context_page_description: PEPPSI is an abbreviation for pyridine-enhanced precatalyst preparation stabilization and initiation. It refers to a group of palladium catalysts developed around 2005 by Prof. Michael G. Organ and co-workers at York University, which can accelerate various aminations and cross-coupling reactions. In comparison to many alternative palladium catalysts, PEPPSI-type complexes are stable to air and moisture and are relatively easy to synthesize and handle.
context_section_description: PEPPSI can catalyze various palladium cross-coupling reactions including Negishi coupling, Suzuki coupling, Sonogashira coupling, Kumada coupling, and the Buchwald–Hartwig amination as well as the Heck reaction. In Negishi coupling, PEPPSI promotes reaction of alkyl halides, aryl halides or alkyl sulfonates with alkylzinc halides, and the important advantage of PEPPSI over alternative catalysts is that the reaction can be carried out in a general chemical laboratory, without a glove box. PEPPSI contains palladium in the +2 oxidation state and is thus a "precatalyst", that is the metal must be reduced to the active Pd(0) form in order to enter the cross-coupling catalytic cycle. This is usually achieved in situ in the presence of active transmetalating agents such as organo-magnesium, -zinc, -tin, or -boron reagents. Once activated, the NHC-Pd(0) species becomes rather air-sensitive.
  An efficient, cationic palladium catalyst of iPEPPSI (internal PEPPSI) type was demonstrated to efficiently catalyse the copper-free Sonogashira reaction in water as the only solvent, under aerobic conditions, in the absence of copper, amines, phosphines and other additives.
caption: Sonogashira coupling under green reaction conditions using iPEPPSI.[9]
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