Synthesis of polymer-supported rhodium(I)-1,3-bis(diphenylphosphino)propane moieties and their use in the heterogeneous hydrogenation of quinoline and benzylideneacetone

A p-styrenyl substituent attached to the ligand framework allows the diphosphine moiety -(C6H4)CH2-OCH2C(CH3)(CH2PPh2)2 to be introduced as a pendant group in cross-linked styrene/divinylbenzene matrixes via free-radical copolymerization. In conjunction with rhodium(I), the POLYDIPHOS material forms an effective heterogeneous catalyst for the hydrogenation of benzylideneacetone to benzylacetone and of quinoline to a mixture of 1,2,3,4-tetrahydroquinoline, 5,6,7,8-tetrahydroquinoline, and decahydroquinoline. The homogeneous behavior of related 1,3-bis(diphenylphosphino)- propane rhodium complexes is different in both activity and selectivity.