Oriented Au nanoplatelets on graphene promote Suzuki-Miyaura coupling with higher efficiency and different reactivity pattern than supported palladium

[EN] Facet 111 oriented Au nanoplatelets (20-40 nm wide, 3-4 nm height) grafted on graphene ((Au) over bar /fl-G) are about three orders of magnitude more efficient than Pd nanoparticles supported on graphene to promote Suzuki-Miyaura coupling. In contrast to Pd catalysis, it is shown here that the product yields in Suzuki-Miyaura coupling catalyzed by Au nanoparticles follow the order chlorobenzene > bromobenzene > iodobenzene. Kinetic studies show that this reactivity order is the result of the poisoning effect of halides for Au that is much higher for I- than Br- and much higher than for Cl-, due to adsorption. This strong iodide adsorption leading to Au catalyst deactivation was predicted by DFT calculations of Au clusters. (Au) over bar /fl-G are about one order of magnitude more efficient than small Au nanoparticles (4-6 nm) obtained by the polyol method supported on graphene. Our results can have impact in organic synthesis, showing the advantage of (Au) over bar /fl-G as catalyst for Suzuki-Miyaura couplings.ADM thanks University Grants Commission (UGC), New Delhi for the award of Assistant Professorship under its Faculty Recharge Programme. ADM also thanks Department of Science and Technology, India, for the financial support through Extra Mural Research funding (SB/FT/CS-166/2013) and the Generalidad Valenciana for financial aid supporting his stay at Valencia through the Prometeo programme. Financial support by the Spanish Ministry of Economy and Competitiveness (CTQ-2012-32315 and Severo Ochoa) and Generalidad Valenciana (Prometeo 2012-014) is gratefully acknowledged. The research leading to these results has received partial funding from the European Community's Seventh Framework Programme (FP7/2007-2013) under grant agreement no. 228862.Candu, N.; Dhakshinamoorthy, A.; Apostol, N.; Teodorescu, C.; Corma Canós, A.; García Gómez, H.; Parvulescu, VI. (2017). Oriented Au nanoplatelets on graphene promote Suzuki-Miyaura coupling with higher efficiency and different reactivity pattern than supported palladium. Journal of Catalysis. 352:59-66. https://doi.org/10.1016/j.jcat.2017.04.034S596635

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Negishi Coupling of Secondary Alkylzinc Halides with Aryl Bromides and Chlorides

An efficient palladium-catalyzed process has been developed for Negishi coupling of secondary alkylzinc halides with a wide range of aryl bromides and activated aryl chlorides. A palladium catalyst composed of a new biaryldialkylphosphine ligand, CPhos, effectively promotes the rate of the reductive elimination step relative to the rate of the undesired β-hydride elimination. The broad substrate scope and excellent ratio of the desired secondary to the undesired primary coupling product make this method a powerful and reliable tool for C(sp[superscript 3])−C(sp[superscript 2]) bond formation.National Institutes of Health (U.S.) (GM 46059)National Institutes of Health (U.S.) (GM 1S10RR13886-01