Au-catalyzed allylation reactions have started to emerge over the past 15 years. However it is striking to note that none of these gold-catalyzed allylation reactions operate via π-allyl complexes, as is classically the case with Pd, Ru and Ir catalysts. Only very recently the first gold π-allyl complexes were prepared and unambiguously authenticated in two parallel studies by Tilset and Bourissou. Recently it was also demonstrated that P^N hemilabile ligands such as MeDalphos trigger the oxidative addition of C(sp2) and C(sp)–X bonds (X = I; Br) to gold under mild conditions. Additionally the P^N ligands support π-coordination and activation of alkenes (and alkynes) at Au(I), as substantiated by the isolation of a variety of π-complexes and their application to the C3-alkylation of indoles. In this work, our aim was to combine the ability of P^N ligands to facilitate oxidative addition and π-coordination at gold to achieve Au(I)/Au(III) catalytic allylation reactions involving π-allyl Au(III) complexes. We found that (MeDalphos)AuCl complexes efficiently catalyze the cross-coupling of indoles with allyl substrates (Scheme 1). The observed selectivity for the branched product suggested a π-allyl intermediate. Further mechanistic investigations by performing every elementary step individually allowed for the characterization of the π-allyl Au(III) intermediate. This transformation represents the first example of a gold-catalyzed allylation reaction operating via a Au(I)/Au(III) cycle and involving π-allyl complexes. As such, this work bridges the gap between gold and the transition metals prevailing in catalytic allylation, namely palladium, ruthenium and iridium which all operate classically via π-allyl complexes.

This talk will discuss a new observation made in the field of bimetallic catalysis: cooperative redox enhancement (CORE). Using alcohol/formyl oxidative dehydrogenation and oxygen reduction as model reactions, it is demonstrated that coupling two separate (but complimentary) processes can lead to significant catalytic rate enhancements. Over spatially separated Au and Pd, it is demonstrated that oxidative dehydrogenation predominantly proceeds on Au sites, while oxygen reduction proceeds on Pd sites. The conclusions derived are based on a combination of thermo- and electrochemical testing, and extensive characterisation was conducted to support the findings. The conclusions drawn have the potential to dramatically influence how researchers approach the design of multicomponent heterogeneous catalysts going forward.

Precise control of the strong metal-support interaction (SMSI) between Au and hydroxyapatite (HAP) enhanced the soft Lewis acidity of Au. Partial substitution of cations in HAP could deposit smaller Au clusters than non-substituted HAP, which further enhanced the cationic properties of Au. Even though Au was partly covered by HAP thin layers for the catalyst with SMSI, the enhanced cationic properties of Au by SMSI surpassed a disadvantage of the decrease in the number of exposed surface Au atoms, resulting in higher catalytic activity than the same catalyst without SMSI.

Gold catalysts have recently been commercialized as a replacement for the highly toxic mercuric chloride acetylene hydrochlorination catalyst. This study investigates the effect of varying levels of support oxidation on the activity of gold catalysts with a focus on producing catalysts which can operate at lower temperatures in existing reactors.

In this event, we would like to present our recent works focused on gold catalysis for the preparation of final high-added value compounds. The formation of propargylamines and 1,3-thiazinane will be discussed. Both species are important for their potential biological properties

In situ electrochemistry and Shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS) was applied to a few studies in monitoring the catalytic process of asymmetric hydrogenation of pro-chiral ketones and semi-hydrogenation of acetylenic bonds on Pt single crystal electrodes. This allows us to understand the structure-activity relationship so that highly efficient catalysts could be designed.