Rhodium catalysts containing polymer-bound

It has also been shown that Rh 80 C in the presence o-f N,N-dimethyl benzyl ami ne, using any one o-f the -following reducing gases H2/CO, H2 or C0/H20[99. The reaction is highly selective and can be also carried out with Amberlyst A-21 resin beads which contained polymer bound N,N-dimethylbenzyl amine moieties which, in turn, imobilized the rhodium cluster. In this latter case an air sensitive catalytic system... 

Linear polystyrene has also been used to support asymmetric hydrogenation catalysts containing chiral diphosphine rhodium(I) complexes (50). Asymmetric hydrogenations of itaconic acid were carried out, forming (R)-2-raethylbutanedioic acid with e.e. s ranging from 20-37%. None of the polymer-bound catalysts were more effective than (-)-DIOP-RhCl and the observed e.e. s were found to be dependent on the molecular weight of the polymer chain, its raicrostructure and solubility. 

Stille et al. have prepared a series of rhodium-bound catalysts containing optically-active diphosphine ligands by two different routes. In some cases, they first prepared monomers containing the diphosphine unit and then performed the polymerization.In other cases, the polymer was treated with excess diphenylphosphide to replace tosylate groups (Schemes 1 and 2). For example, the optically-active monomer 2-p-styryl-4,5-6/5[(tosyloxy)methyl]-l,3-dioxolane was polymerized with a variety of co-monomers to provide polymer-attached optically active ligands for... 

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