Abstract
Palladium nanoparticles (Pd NPs) synthesized by the metal vapor synthesis technique were supported on poly(4-vinylpyridine) 2% cross-linked with divinylbenzene (Pd/PVPy). Transmission electron microscopy revealed the presence of small metal nanoparticles (dm = 2.9 nm) highly dispersed on the PVPy. The Pd/PVPy system showed high catalytic efficiency in Suzuki-Miyaura carbon–carbon coupling reactions of both non-activated and deactivated aromatic iodides and bromides with aryl boronic acids, carried out under an air atmosphere. The high turnover of the catalyst and the ability of the PVPy resin to retain active Pd species are highlighted. By comparing the catalytic performances of Pd/PVPy with those observed by using commercially available Pd-based supported catalysts, the reported system showed higher selectivity and lower Pd leaching.
Highlights
The palladium-catalyzed coupling of organoboron reagents with aryl halides, known as the Suzuki–Miyaura reaction [1,2,3] is one of the most convenient and powerful synthetic methods for the preparation of biaryl and alkene derivatives that are essential components of natural products, pharmaceuticals, agrochemicals, and polymers [4,5,6]
Homogeneous palladium catalysts are typically not reusable and the products are often contaminated by residual palladium and/or ligands, which in turn are difficult to separate from the products [3,21]
We described the preparation of Pd NPs by metal vapor synthesis (MVS)
Summary
The palladium-catalyzed coupling of organoboron reagents with aryl halides, known as the Suzuki–Miyaura reaction [1,2,3] is one of the most convenient and powerful synthetic methods for the preparation of biaryl and alkene derivatives that are essential components of natural products, pharmaceuticals, agrochemicals, and polymers [4,5,6]. Traditional reaction conditions for Suzuki–Miyaura couplings involve the use of homogeneous palladium catalysts containing phosphine ligands [1,8,9,10,11] or N-heterocyclic carbene ligands [12,13,14]. This reaction is the most intensively investigated among C−C couplings in the last decade [15,16,17]. These limitations of Catalysts 2020, 10, 330; doi:10.3390/catal10030330 www.mdpi.com/journal/catalysts
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