Finely dispersed palladium on silk‐fibroin as an efficient and ligand‐free catalyst for Heck cross‐coupling reaction

Abstract

A palladium-fibroin complex (Pd/Fib.) was prepared by the addition of sonicated fibroin fiber in water to palladium acetate solution. Pd (OAc) 2 was absorbed by fibroin and reduced with NaBH 4 at room temperature to the Pd(0) nanoparticles. Powder-X-ray diffraction, scanning electron microscopyenergy-dispersive X-ray spectroscopy, Fourier transform-infrared, CHN elemental analysis and inductively coupled plasma-atomic emission spectroscopy were carried out to characterize the Pd/Fib. catalyst. Catalytic activity of this finely dispersed palladium was examined in the Heck coupling reaction.The catalytic coupling of aryl halides (-Cl, -Br, -I) and olefins led to the formation of the corresponding coupled products in moderate to high yields under air atmosphere. A variety of substrates, including electron-rich and electronpoor aryl halides, were converted smoothly to the targeted products in simple procedure. Heterogeneous supported Pd catalyst can be recycled and reused several times.

Palladium Supported on Bioinspired Materials as Catalysts for C–C Coupling Reactions

“…Mizoroki-Heck coupling reactions of aryl iodides with terminal alkenes promoted by Pd-fibroin (Pd/Fib.) complex, reported in 2019 by Mirzaei and co-workers [144].…”

“…An easy methodology for the synthesis of an efficient Pd-fibroin (Pd/Fib.) complex was reported by Mirzaei et al [144]. Palladium acetate was sonicated in water with the degummed protein and then reduced with NaBH 4 at room temperature to provide Pd (0) nanoparticles.…”

Chemical Modification of Silk Proteins via Palladium‐Mediated Suzuki−Miyaura Reactions

“…[24][25][26][27] Interestingly, silk fibroin has been used in Suzuki-Miyaura, Heck, and Ullmann cross-coupling reactions, but in these instances, the protein served only as a support for the Pd catalyst and was not the target for cross-coupling. [28][29][30] To the best of our knowledge, no work has been published for the functionalization of silk fibroin via Pd-catalyzed cross-coupling reactions.…”