Polyionic Amberlite resin formate (ARF), derived from commercially available Amberlite resin chloride by simple rinsing with aqueous formic acid, could be soaked with palladium(0) from palladium salts, the formate counteranion being the reducing source. The resulting Amberlite resin formate supported with palladium(0), ARF-Pd, showed excellent catalytic activity in Heck, Suzuki-Miyaura, and Sonogashira couplings with a range of substrates. The catalyst may be recovered easily and quantitatively without leaching and recycled; it was tested for five runs without any significant loss of activity.Transition-metal-catalyzed organic reactions constitute the central part of contemporary organic synthesis. In particular, palladium-catalyzed C-C bond-forming processes are foremost in the arena of organic process development. 1 The Heck, Suzuki-Miyaura, and Sonogashira reactions are excellent tools for C-C coupling reactions between aryl halides or triflates and suitable partners. 1d Over the last decade, commendable research has been performed and significant developments have been made and practical methodologies have been established. Widespread uses of palladium-catalyzed coupling reactions are found in modern organic synthesis, because the resulting coupled products often find good applications in the preparation of materials, 2 pharmaceuticals, 3 and other bioactive compounds. 4Since the common facet of these C-C coupling reactions is the palladium, which acts as the catalyst, numerous attempts have been made to employ it as either a soluble homogeneous 5 or an immobilized heterogeneous catalyst. 6 Soluble homogeneous palladium catalysts are found to have significant activity in various coupling reactions, but there are drawbacks, such as less active or inactive colloidal species, the catalyst is unrecoverable, the possibility of product contamination, and cost, that are often encountered in the course of such reactions. 7 Consequently, several approaches have been explored utilizing various immobilization techniques on solid or colloidal supports, 8 with the aim of efficient recovery and reuse of the active catalysts. The major thrust for achieving success in designing and developing polymer-supported metal catalysts broadly include: improved stability within the polymer matrix, increased selectivity for reactions, enhanced regioselectivity, phosphine-free, reusable for several runs, and superior asymmetric induction due to sitespecific chiral catalysts. In the past few years, several attempts have been made to surmount the problems pertaining to high reaction temperatures, separation of pure products, and recovery and reuse of palladium complexes by the use of heterogeneous palladium systems. Palladium-on-carbon, 9a carbon nanotubes, 9b and palladium on different metal oxides, 9 silica gel and modified silica gel, 10 fluorous silica, 10e,f zeolites, 11 molecular sieves, 12 hydrotalcite, 13 and sepiolites 14 were found to be suitable catalysts for some reactions. Several groups have examined the use of polymer/dend...
