Palladium-Catalyzed Cross-Coupling in Aqueous Media: Recent Progress and Current Applications

Abstract

Water has attracted significant attention as an alternative solvent for homogeneous metal-catalyzed reactions because it is a non-toxic, nonflammable solvent that can allow for simplified recovery of homogeneous catalysts. The use of water as a solvent in palladium-catalyzed cross-coupling reactions is of great academic and industrial interest. Palladium-catalyzed coupling reactions are powerful methods to make carbon-carbon and carbon-heteroatom bonds under mild conditions. Separation of the catalyst from the organic product can be very difficult; however, constraining the catalyst to the aqueous-phase of an aqueous-biphasic solvent system can potentially simplify catalyst recovery. This review will focus on recent developments in the design and application of aqueous-phase, palladium-catalyzed coupling reactions over the period from 2000, through late 2004. A variety of new hydrophilic ligand architectures have been introduced recently that provide significantly more active catalysts towards industrially relevant aryl bromides and chlorides. Stille CouplingRSiX3 L n Pd(Cat) Hiyama Coupling

Palladium Nanoparticles Supported on Polyaniline Nanofibers as a Semi‐Heterogeneous Catalyst in Water

“…In addition, water is an attractive "green" solvent and very inexpensive. [13][14][15][16] Another limitation of Suzuki coupling is that more economical aryl chlorides are less reactive than aryl bromides and iodides, and protocols for such reactions conducted in water are few. [17][18][19][20][21][22][23] Furthermore, Suzuki coupling catalyzed by other palladium nanoparticles [24,25] generally does not work with aryl chlorides.…”

Amination of Allylic Alcohols in Water at Room Temperature

“…These reactions occur in excellent yields, without inert atmosphere conditions, in water as the only medium, 13 and at room temperature. Further applications from our laboratory will be described in due course.…”

2‐Hydroxyethyl‐Substituted (NHC)Pd(II)PPh3 Complexes: Synthesis, Characterization, Crystal Structure and Its Application on Sonogashira Cross‐Coupling Reactions in Aqueous Media

“…NHCs have a natural advantage over phosphines because of their design as the water‐soluble catalyst, strong σ‐donor, weakly π‐acceptor, thermal and oxidative stability, electronic and sterically adjustability etc . The development of water‐soluble Pd complexes as highly effective catalysts for cross‐coupling reactions in aqueous medium has become an extensive research area in the latter half of the twentieth century . In particular, the development of the water‐soluble catalysts of Pd‐based NHC complexes has recently attracted considerable attention ,…”