Synthesis of Bis(phosphane) Palladium and Rhodium Complexes on a Polyethylene Oxide Grafted Polystyrene Matrix (TentaGel) and the Catalytic Behavior of the Rhodium Complexes

A new polymer-attached rhodium catalyst on a polyethylene oxide-grafted styrene matrix (TentaGel) is described. The corresponding anchor molecules were prepared by starting from different Boc-protected chiral pyrrolidinebis(ph0sphane)Pd complexes. The crystal structure of [3R,4R)-N-(4-carboxybutanoyl) -3,4 -bis (diphenylphosphany1)pyrrolidine-P, P’] diiodopalladium ( lc ) was determined. The formation of an amide bond between TentaGel and anchor molecules resulted in polymer-bound Pd bisphosphane complexes. Decomplexation of the Pd with cyanide and reaction of the free polymeric ligand with [Rh(COD),]BF, led to the active hydrogenation catalyst. The influence of different solvents on the swelling volume and the catalytic behavior was tested. The polymer-bound rhodium complex [(3R,4R)-N-( 1,5-dioxo-5TentaGel-amino-pentyl) -3,4-bis (diphenylphosphany1)pyrrolidineP,P‘] (1,5-cyclooctadiene)rhodim tetrafluoroborate (7) has about the same catalytic activity and enantioselectivity as the homogeneous complex [(3R,4R)-N-(fert-butoxycarbonyl)-3,4-bis( diphenylphosphany1)pyrrolidine-P, P’] ( 1,5 -cyc1ooctadiene)rhodium tetrafluoroborate (9) in the same solvent mixture. It is possible to reuse 7 once, then it abruptly loses activity. This behavior remains to be clarified.