Directed C−H Activation and Tandem Cross‐Coupling Reactions Using Palladium Nanocatalysts with Controlled Oxidation

Abstract

Controlled oxidation of palladium nanoparticles provided high-valent Pd oxo-clusters which efficiently promote directed C-H halogenation reactions. In addition, palladium nanoparticles can undergo changes in oxidation states to provide both high-valent Pd and low-valent Pd species within one system, and thus a tandem reaction of C-H halogenation and cross-coupling (C-N, C-C, and C-S bond formation) was successfully established.

In situ XAS study of the local structure and oxidation state evolution of palladium in a reduced graphene oxide supported Pd(ii) carbene complex during an undirected C–H acetoxylation reaction

“…Kim and co-workers have shown the co-existence of Pd(0), PdIJII) and PdIJIV) species by oxidizing Pd nanoparticles at controlled conditions where PdIJIV) formed polymeric species with enhanced stability. 13 Although such PdIJIV) signals are not observed in the EXAFS of our material, it can be attributed to its low content.…”

“…Also, the oxidation state evolution during directed catalysis with Pd nanoparticles has been studied. 13 However, there are few, if any, experimental studies on the nature and particularly oxidation state of the Pd catalytic species during undirected C-H activation. Many of the traditional techniques used for characterization of catalysts are either difficult to conduct under reaction conditions, such as X-ray photoelectron spectroscopy (XPS), or unable to probe the catalytic centres directly, such as Fourier-transform infrared (FTIR) spectroscopy.…”

Palladium and Copper: Advantageous Nanocatalysts for Multi-Step Transformations

“…In addition, stabilized PdNPs were successfully recycled for at least five runs without loss of activity. [131]. Scheme 31.…”

“…As discussed above, heterocycles are building blocks commonly found in natural and biologically active compounds as well as in commercialized drugs (Scheme 32). [131]. Scheme 31.…”

Metal Nanoparticles as Sustainable Tools for C–N Bond Formation via C–H Activation

“…Although homogeneous metal complexes are highly efficient in C–H activation reactions [ 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 ], their difficult reusability and the inevitable waste produced from their separation from reaction products constitutes an important limitation for their actual use. To overcome these issues and improve the sustainability of C–H functionalization reactions, the design and use of heterogeneous catalysis is a valid yet challenging option [ 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 ].…”