Development of dendrimer-bound palladium complexes via electrostatic interaction

摘要

Poly (propylene imine) (PPI) dendrimers were alkylated using decanoyl chloride to give Gn-C 10 dendrimers (n=3,4,5). Treatment of [PdCl(C_3H_5)]_2 with 4-(diphenyl-phosphino) benzoic acid and Gn-C 10 afforded the dendrimer-encapsulated Pd complexes, which could catalyze the Mizoroki-Heck reaction of iodobenzene and n-butylacrylate in toluene. However, the reaction did not proceed in the absence of Gn-C 10 under the present conditions. The reaction rates increased with increasing the generation of the dendrimers. Use of the 5 th generation dendrimer gave the high stability of the Pd complex even in a low P/Pd ratio of 1. The above phenomena of the catalytic activity and stability are attributed to the high density of inner amino groups within the dendrimers which provide the polar nanoenvironment around Pd species and coordinate to the Pd complex. Additionally, the dendrimers encapsulating the Pd complexes act as unique nanoreactors for allylic amination and hydrogenation of dienes.