Small molecule transformation reactions, such as carbon–carbon cross-coupling reactions are a very important process in organic chemistry, the Pd-catalyzed Suzuki-Miyaura Coupling (SMC) reaction developed last century is one of the most efficient and wildly used ones in both laboratory and industry. Traditionally, in the homogeneous systems, where molecular Pd catalysts are usually used, the reaction is usually performed under heating and highly dependent on phosphine-based ligands to obtain satisfactory selectivity and conversion. Meanwhile, the procedure for preparing these particular ligands is rather complicated with a high cost. Moreover, the molecular Pd complexes are expensive and difficult to be recovered and reused in the homogeneous systems. Another serious problem is that the residual metal in the final product must also be addressed adequately. To overcome these problems, heterogeneous Pd catalysts have attracted much attention. Although significant efforts and progress have been made, the design and preparation of efficient heterogeneous catalysts are still challenging and essential from the economic and environmental points of view. As mentioned above, SACs provide new opportunities for the society of catalysis, building a bridge between homogeneous and heterogeneous catalysis.<br/>We have recently developed a new single atom Pd catalyst anchored on bi-metal oxides (ZnO-ZrO2). Pd-ZnO-ZrO2 can be fabricated in multi-grams scale using a facile in-situ coprecipitation method. The material decorated with atomically dispersed Pd on the surface of mesoporous bimetal oxide, which was confirmed by aberration-corrected high-angle annular dark-field scanning transmission electron microscopy. The single atom Pd catalyst, ppm level Pd, was used in Suzuki-Miyaura Coupling reaction under phosphine-free, open air and mild conditions. The catalytic system can tolerate various substrates to obtain moderate to very high reaction yields. Notably, the TON number was up to 65,124 for the reaction between bromobenzene and p-tolylboronic acid in a single run. The facile preparation and excellent performance of the new catalyst endow this catalytic system with great potential in practical applications.

Pd Single atom catalyst for small molecule transformations under practical conditions

2019 Fall National Meeting

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