FibreCat palladium catalysts

The commercially available palladium catalyst FibreCat has also been applied to the Suzuki reaction [53]. The polymer-supported catalyst with microwave heating gave rise to cross-coupled product in good yield as exemplified in the transformation of 152 and 153 into arylpyridine 154. 

Some of the most remarkable achievements include microencapsulation in polystyrenes such as entrapped 0s04 for olefin hydroxylation (exploiting the interaction between n-electrons of benzene rings of the polystyrenes used as polymer backbones and the vacant orbitals of the catalysts) 5 polyurea-entrapped palladium (PdEnCat)6 for a multiplicity of C C forming reactions and the use of carboxylic acid-functionalized polymer (FibreCat).7 In general, however, metal leaching cannot be avoided. The PdEnCat catalyst, for instance, leaches some 4% of palladium per catalytic reaction run. 

The use of palladium attached to FibreCat catalysts in simple Heck and Suzuki reactions has already been described (1). This work has now been extended to cover a wider variety of FibreCat systems (Figure 1) in the more difficult Suzuki coupling of aryl chlorides (3,4). (NB FibreCat 1000-Dl, D2 and D3 are experimental samples, whereas 1000-D7, D8 and 1001 are all commercially... 

The use and the advantages of these catalysts are described in several papers especially for palladium-catalyzed coupling reactions [66,96,97]. Levels of selectivity have been compared with those achievable with conventional homogeneous catalysts in a variety of reactions. In general the FibreCat versions show comparable activities to the non-anchored versions. 

Further efficient polymeric palladium complexes containing Pd(OAc)2, Pd(dba), Pd(MeCN)Cl2, Pd(PhCN)Cl2 and (7i-allyl)PdCl anchored onto the polyethylene-bounded triphenylphosphine are called FibreCat catalysts [141] ... 

---