Polymer resin ruthenium

Solid-phase synthesis is of importance in combinatorial chemistry. As already mentioned RuH2(PPh3)4 catalyst can be used as an alternative to the conventional Lewis acid or base catalyst. When one uses polymer-supported cyanoacetate 37, which can be readily obtained from the commercially available polystyrene Wang resin and cyanoacetic acid, the ruthenium-catalyzed Knoevenagel and Michael reactions can be performed successively [27]. The effectiveness of this reaction is demonstrated by the sequential four-component reaction on solid phase as shown in Scheme 11 [27]. The ruthenium-catalyzed condensation of 37 with propanal and subsequent addition of diethyl malonate and methyl vinyl ketone in TH F at 50 °C gave the adduct 40 diastereoselectively in 40 % yield (de= 90 10). 

Polymer-supported synthesis of 1,3-dienes by efficient ruthenium-catalyzed in-termolecular enyne metathesis has been reported by Schiirer and Blechert [99]. The polystyrene resin, containing a propargyl ester moiety, was reacted with functionalized alkene in the presence of Cl2(PCy3)2Ru(=CHPh). The dienes obtained were cleaved from the polymer support using a paladium-catalyzed reaction with different nucleophiles (Eq. 57). 

More recently, chiral Ru-porphyrin polymers were used for catalytic asymmetric carbene transfer. A C2-symmetric group containing two norbomane moieties fused to the central vinyl substituted benzene ring of a porphyrin was chosen in order to induce the chirality. Then the chiral ruthenium vinylporphyrin 101 was involved into radical copolymerization with styrene and DVB or EGDMA to lead respectively to monolithic resins chiral 102 and 103 which were crushed (Scheme 48). 

Tentagel, described above, is in wide use today in solid phase syntheses. Polyethylene glycol has also been attached to various other polymers to form support resins. For instance, Frechet and coworkers [37] used cross-linked methacrylate esters of ethylene glycol oligomers in a suspension polymerization to synthesize hydroxyl group functionalized beads. These beads swell well in a variety of polar solvents. Another example is that of Grubbs attaching a ruthenium metathesis catalyst to polyethylene [38] ... 

Hetorogenized Catalysts.—Reaction of [Ru(NH3)60H] + with a Faujasite-type zeolite gives a supported Ru complex, which effects hydroformylation of ethylene the catalytic species may be ruthenium clusters that are trapped in the zeolite cages. The effect of reaction conditions upon the selectivity of the hydroformylation of methyl methacrylate with [RhH(CO)(PPh3)3] or its polymer-anchored analogue has been investigated and hydroformylation of hex-l-ene and cyclo-octa-1,5-diene has been carried out with cobalt, rhodium, and platinum-tin complexes anchored to an ion-exchange resin via quaternary amino-phosphines. ... 

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