Sonogashira Coupling of Aryl Halides Catalyzed by Palladium on Charcoal

Abstract

With the proper choice of solvent, palladium on charcoal acts as an efficient catalyst in the Sonogashira cross-coupling reaction of aryl bromides. The catalytically active species in the process is probably palladium, which leaches into the solution but returns onto the surface of the charcoal at the end of the reaction.

Cross‐Coupling Reactions to sp Carbon Atoms

“…This active catalytic system requires only a small amount of Pd leached into the solution to proceed (1.8% observed by atomic absorption measurements), which allows for recovery and reuse of the remaining Pd/C without significant loss of bound Pd metal. On recycling the Pd/C, cross-coupling indeed occurred, although the catalytic activity decreased with each successive use [96]. This effect has also been observed for a new form of palladium on charcoal, which has been prepared by dissolution of Pd(NO 3 ) 2 in water, addition of activated charcoal, and ultrasonication followed by drying [101].…”

Sandwich Immunoassay as a High‐Throughput Screening Method for Cross‐Coupling Reactions

“…Although the low cost, ease of handling, and high recovery are previously established advantages of heterogeneous catalysts, their use in the Sonogashira reaction is not well documented. [17] The catalyst library was prepared through the combination of a set of four homogeneous and eight solid-supported palladium sources as well as eight cocatalysts (copper, silver, or gold sources). These 96 catalytic reactions were run in a parallel manner, quenched by the addition of trifluoroacetic acid (TFA), diluted to the appropriate concentration with phosphate buffer, and assayed directly by a sandwich immunoassay (see Experimental Section).…”

Palladium‐Katalysatorsysteme für die Synthese von konjugierten Eninen durch Sonogashira‐Kupplungen und verwandte Alkinylierungen

“…Eine Reihe weiterer Strategien nutzt wasserhaltige Lö-sungsmittelgemische: Kreuzkupplungen mit Palladium/Aktivkohle oder Palladiumpulver als Katalysator, [102][103][104][105] Nickelund übergangsmetallfreie Katalysen, [106][107][108] trägergebundene Liganden und Komplexe [109][110][111] oder ligandenfreie Katalysen. [84] Diese Methoden werden in den entsprechenden Abschnitten besprochen.…”