Diphenylphosphorylated PEG (DPPPEG) as a new support for generation of nano-Pd(0) as catalyst for carbon-carbon bond formation via copper-free Sonogashira and homocoupling reactions of aryl halides in PEG

摘要

In this study, synthesis and application of diphenylphosphorylated PEG(200) (DPPPEG(200)) are described. Herein, we report a very simple procedure for the preparation of DPPPEG(200) as a stable solid through the reaction of PEG(200) with ClPPh2. This compound was used as a very suitable ligand for the in situ generation of nano-Pd(0) particles through its reaction with PdCl2 as a pre-catalyst. Isolation of this catalyst is very simple through addition of diethyl ether to the reaction mixture and centrifugations. Full characterization of the nano-Pd(0)/DPPPEG(200) was performed by XRD spectra, UV-Vis spectra, and also by TEM image. This nano-complex was used as an efficient catalyst for copper-free Sonogashira and homocoupling reactions of aryl halides. The sonogashira reaction of aryl halides was conducted at 80 degrees C in PEG. However, the homocoupling reaction was performed at 100 degrees C for aryl iodides and activated aryl bromides and at 130 degrees C for deactivated aryl bromides and aryl chlorides in PEG. The catalyst was recovered and recycled for four consecutive runs.