Light-Induced Mechanistic Divergence in Gold(I) Catalysis: Revisiting the Reactivity of Diazonium Salts

Straightforward Access to Isoindoles and 1,2-Dihydrophthalazines Enabled by a Gold-Catalyzed Three-Component Reaction

We describe herein a gold-catalyzed three-component reaction of o-alkynylbenzaldehydes, aryldiazonium salts, and trimethoxybenzene. This process enables the one-pot formation of valuable isoindoles and 1,2-dihydrophathalazines. The regioselectivity of the reaction is dictated by the nature of the aryldiazonium salt. Noticeably, the reaction is performed at room temperature under mild conditions and tolerates a variety of functional groups on both the o-alkynylbenzaldehyde and the aryldiazonium salt. Experimental mechanistic studies suggest that it is catalyzed by arylAu(III) species.

Computational Insights into the Photoinduced Dimeric Gold-Catalyzed Divergent Dechloroalkylation of gem-Dichloroalkanes with Alkenes

The employment of dinuclear Au(I) catalysts in photomediated modern organic transformations has attracted significant attention over the past decade, which commonly demonstrates unique catalytic performance compared with the corresponding mononuclear gold complexes. Nevertheless, detailed mechanisms of dinuclear gold catalysis remain ambiguous, and further mechanistic understanding is highly desirable. Herein, computational studies were carried out to gain mechanistic insights into the photoinduced dinuclear gold-catalyzed divergent dechloroalkylation of gem-dichloroalkanes. Computational results suggest that a proton transfer from the additive, Hantzsch ester (HE), to the base, guanidine, could lead to an ionic pair complex, which is ready to undergo excitation under blue light irradiation to result in the corresponding triplet excited state. Then, the excited complex might undergo oxidative quenching with the dinuclear gold photocatalyst [AuI-AuI]2+, via a single-electron-transfer (SET) step to afford an unusual [Au1/2-Au1/2]+ dinuclear species. The corresponding mononuclear gold catalyst, [AuI]+, however, is not ready to enable the analogous step to give a [Au0] species, which might account for the unique characteristics of dinuclear gold catalysis. Subsequently, the formed [Au1/2-Au1/2]+ intermediate could trigger a Cl-atom transfer from dichloromethane in an inner-sphere manner to furnish a critical chloromethyl radical. Next, the resulting chloromethyl radical could attack the alkenyl moiety of substrates to generate the corresponding alkyl radicals. Then, three possible mechanistic pathways were explored to rationalize the substrate-dependent divergent transformations in this protocol. The main factors responsible for the diversified transformations were discussed.

Multi-substituted trifluoromethyl alkene construction via gold-catalyzed fluoroarylation of gem-difluoroallenes

An unprecedented fluoroarylation of 1,1-difluoroallenes with a cost-effective nucleophilic fluoride reagent and aryldiazonium salts is reported. This visible light promoted gold-catalyzed reaction allows a stereo- and regioselective incorporation of both the fluorine atom and aryl group, enabling a straightforward construction of multi-substituted trifluoromethyl alkenes. Under the mild reaction conditions, a nice tolerance of diverse functional groups is achieved. The high regioselectivity for fluorine-incorporation is rationalized by considering the thermodynamic driving force of trifluoromethyl group formation, whereas the counterintuitive stereoselectivity that aryl is installed on the side of the bulkier γ-substituent is interpreted by alleviating the increasing 1,3-allylic interaction in the gold-coordinated allene intermediate en route to the product.

Gold(I)-Catalyzed Substitution-Controlled Syntheses of Spiro[indoline-3,3'-pyrrolidine] and Spiro[indoline-3,3'-piperidine] Derivatives

Spiro[indoline-3,3'-pyrrolidine] and spiro[indoline-3,3'-piperidine] derivatives were synthesized in a substitution-controlled manner under the catalysis of cationic gold(I) species in the presence of Hantzsch ester (HEH). The optimal reaction condition was determined by screening, and the functional group tolerances of these two pathways were examined by readily synthetic substrates. The endo and exo selectivities of these cyclizations were elucidated by density functional theory calculations, and a plausible mechanism for these transformations was proposed.

Site-Selective Arylation of Carboxamides from Unprotected Peptides

The amidated peptides are an important class of biologically active compounds due to their unique biological properties and wide applications as potential peptide drugs and biomarkers. Despite the abundance of free amide motifs (Asn, Gln, and C-terminal amide) in native peptides, late-stage modification of the amide unit in naturally occurring peptides remains very rare because of the intrinsically weak nucleophilicity of amides and the interference of multiple competing nucleophilic residues, which generally lead to undesired side reactions. Herein, chemoselective arylation of amides in unprotected polypeptides has been developed under an air atmosphere to afford the N-aryl amide peptides bearing various functional motifs. Its success relies on the combination of gold catalysis and silver salt to differentiate the relative inert amide among a collection of reactive nucleophilic amino acid residues (e.g., -NH₂, -OH, and -COOH), favoring the C-N bond coupling toward amides over other more nucleophilic groups. Experimental and DFT studies reveal a crucial role of the silver cation, which serves as a transient coordination mask of the more reactive reaction sites, overcoming the inherently low reactivity of amides. The excellent biocompatibility of this strategy has been applied to functionalize a wide range of peptide drugs and complex peptides. The application could be further extended to peptide labeling and peptide stapling.

Gold-catalyzed multicomponent reactions

Multicomponent reactions (MCRs) have emerged as an important branch in organic synthesis for the creation of complex molecular structures. This review is focused on gold-catalyzed MCRs with a special emphasis on the recent developments.

Surface and Interface Coordination Chemistry Learned from Model Heterogeneous Metal Nanocatalysts: From Atomically Dispersed Catalysts to Atomically Precise Clusters

The surface and interface coordination structures of heterogeneous metal catalysts are crucial to their catalytic performance. However, the complicated surface and interface structures of heterogeneous catalysts make it challenging to identify the molecular-level structure of their active sites and thus precisely control their performance. To address this challenge, atomically dispersed metal catalysts (ADMCs) and ligand-protected atomically precise metal clusters (APMCs) have been emerging as two important classes of model heterogeneous catalysts in recent years, helping to build bridge between homogeneous and heterogeneous catalysis. This review illustrates how the surface and interface coordination chemistry of these two types of model catalysts determines the catalytic performance from multiple dimensions. The section of ADMCs starts with the local coordination structure of metal sites at the metal-support interface, and then focuses on the effects of coordinating atoms, including their basicity and hardness/softness. Studies are also summarized to discuss the cooperativity achieved by dual metal sites and remote effects. In the section of APMCs, the roles of surface ligands and supports in determining the catalytic activity, selectivity, and stability of APMCs are illustrated. Finally, some personal perspectives on the further development of surface coordination and interface chemistry for model heterogeneous metal catalysts are presented.

Gold-Catalyzed Enynal and Enynol Coupling by Selectively Steering Two Transient Vinyl-Gold Intermediates

The vinyl-gold bond is easily accessible but less exploited in homogeneous gold catalysis, which possesses weak nucleophilicity and would be likely to undergo protodemetalation. Herein, a gold-catalyzed enynal and enynol coupling by selectively steering two transient vinyl-gold intermediates is realized under mild conditions. It exhibits high atom economy and good tolerance of functional groups with the added benefit of operational simplicity. The control experiments indicated that the in situ formed vinyl-gold accounts for the reactivity.

N-Heterocyclic Carbene-Stabilized Gold Nanoclusters with Organometallic Motifs for Promoting Catalysis

The complexity of heterogeneous metal catalysts makes it challenging to gain insights into their catalytic mechanisms. Thus, there exists a huge gap between heterogeneous catalysis and organometallic catalysis. With the success in the preparation of highly robust atomically precise metal nanocluster catalysts (i.e., [Au₁₆(NHC-1)₅(PA)₃Br₂]³⁺ and [Au₁₇(NHC-1)₄(PA)₄Br₄]⁺, where NHC-1 is a bidentate NHC ligand, and PA is phenylacetylide) with surface organometallic motifs anchored on the metallic core, we demonstrate in this work how the metallic core works synergistically with the surface organometallic motifs to enhance the catalysis. More importantly, the discovery allows the development of highly stable and recyclable heterogeneous metal catalysts to achieve efficient hydroamination of alkynes with an extremely low catalyst dosage (0.002 mol %), helping bridge the gap between heterogeneous and homogeneous metal catalysis. The surface modification of metal nanocatalysts with organometallic motifs provides a new design principle of metal catalysts with enhanced catalysis.

Reactant-induced photoactivation of in situ generated organogold intermediates leading to alkynylated indoles via Csp2-Csp cross-coupling

Photosensitization of organogold intermediates is an emerging field in catalysis. In this context, an access to 2,3-disubstituted indoles from o-alkynyl aniline and iodoalkyne derivatives via a gold-catalyzed sequence under visible-light irradiation and in the absence of an exogenous photocatalyst was uncovered. A wide scope of the process is observed. Of note, 2-iodo-ynamides can be used as electrophiles in this cross-coupling reaction. The resulting N-alkynyl indoles lend themselves to post-functionalization affording valuable scaffolds, notably benzo[a]carbazoles. Mechanistic studies converge on the fact that a potassium sulfonyl amide generates emissive aggregates in the reaction medium. Static quenching of these aggregates by a vinylgold(I) intermediate yields to an excited state of the latter, which can react with an electrophile via oxidative addition and reductive elimination to forge the key C-C bond. This reactant-induced photoactivation of an organogold intermediate opens rich perspectives in the field of cross-coupling reactions.

Visible Light-Induced Transition Metal Catalysis

In recent years, visible light-induced transition metal catalysis has emerged as a new paradigm in organic photocatalysis, which has led to the discovery of unprecedented transformations as well as the improvement of known reactions. In this subfield of photocatalysis, a transition metal complex serves a double duty by harvesting photon energy and then enabling bond forming/breaking events mostly via a single catalytic cycle, thus contrasting the established dual photocatalysis in which an exogenous photosensitizer is employed. In addition, this approach often synergistically combines catalyst-substrate interaction with photoinduced process, a feature that is uncommon in conventional photoredox chemistry. This Review describes the early development and recent advances of this emerging field.

Key role of a π–π complex in diaryl cross-coupling between aryldiazonium salts and arylboronic acids using photosensitizer-free gold/photoredox catalysis

In a new mechanism for photosensitizer-free visible-light-mediated gold-catalyzed cross-coupling, the π–π complex between aryldiazonium salts and arylboronic acids acts as a photoinitiator.

Merging Gold/Copper Catalysis and Copper/Photoredox Catalysis: An Approach to Alkyl Oxazoles from N-Propargylamides

Here, we report a mild and highly efficient approach to alkyl oxazoles through merging gold/copper catalysis and copper/photoredox catalysis. Various alkyl oxazoles are synthesized from N-propargylamides with alkyl halides in good to excellent yields with wide functional-group compatibility under blue-light irradiation. Significantly, a copper catalyst plays a dual role in this transformation: as a powerful cocatalyst to accelerate protodeauration of vinyl gold intermediates and improve photoredox catalysis.

Gold catalyzed efficient preparation of dihydrobenzofuran from 1,3-enyne and phenol

A gold catalyzed formal intermolecular [2+3] cyclo-coupling of 1,3-enynes with phenols was developed to prepare dihydrobenzofuran derivatives with the addition of 2,6-dichloropyridine N-oxide, in which, a highly ortho-selective phenol S_EAr functionalization was achieved by using 1,3-enynes as α-oxo vinyl gold carbenoid surrogates.

Metallaphotoredox: The Merger of Photoredox and Transition Metal Catalysis

The merger of photoredox catalysis with transition metal catalysis, termed metallaphotoredox catalysis, has become a mainstay in synthetic methodology over the past decade. Metallaphotoredox catalysis has combined the unparalleled capacity of transition metal catalysis for bond formation with the broad utility of photoinduced electron- and energy-transfer processes. Photocatalytic substrate activation has allowed the engagement of simple starting materials in metal-mediated bond-forming processes. Moreover, electron or energy transfer directly with key organometallic intermediates has provided novel activation modes entirely complementary to traditional catalytic platforms. This Review details and contextualizes the advancements in molecule construction brought forth by metallaphotocatalysis.

Switchable Divergent Synthesis in Gold-Catalyzed Difunctionalizations of o-Alkynylbenzenesulfonamides with Aryldiazonium Salts

Gold-catalyzed difunctionalizations of o-alkynylbenzenesulfonamides with aryldiazonium salts are reported herein. Upon irradiation with the blue LEDs, benzosultam products were formed via aminoarylation accompanied by the release of N₂. Without irradiation, aryldiazonium salts were engaged as efficient electrophiles, facilitating electrophilic deaurations of the vinyl-Au(I) intermediates, followed by tautomerization to give the N-aryl-substituted α-imino (E)-hydrazones. The regioselectivities of 6-endo-dig and 5-exo-dig cyclizations were excellent.

Using Light to Modify the Selectivity of Transition Metal Catalysed Transformations

Light has a remarkable and often unique ability to promote chemical reactions. In combination with transition metal catalysis, it offers exciting opportunities to modify catalyst function in a non-invasive manner, most frequently being reported to switch on or accelerate reactions that do not occur in the dark. However, the ability to completely change reactivity or selectivity between two different reaction outcomes is considerably less common. In this Minireview we bring together examples of this concept and highlight their mechanistically distinct approaches. Our overview demonstrates how these non-natural, photo-switchable systems provide key fundamental mechanistic insights, enhancing our understanding and stimulating development of new catalytic activity, and how this might lead to tangible applications, impacting fields such as polymer chemistry.

Gold-Catalyzed One-Pot Synthesis of Polyfluoroalkylated Oxazoles from N-Propargylamides Under Visible-Light Irradiation

A gold-catalyzed synthesis of polyfluoroalkylated oxazoles from N-propargylamides under visible-light irradiation has been developed. These reactions display excellent compatibility of radicals and gold catalysts under visible-light irradiation. Mechanistic experiments indicate that polyfluoroalkyl iodides play a dual role in enhanced compatibility of radicals and gold catalysts through assisted protodeauration of vinyl gold and reactivated the gold catalyst. In addition, PPh₃ AuNTf₂ not only activates N-propargylamide to generate vinyl gold intermediate, but also greatly promotes homolysis of polyfluoroalkyl iodides under blue light irradiation.

The interplay of carbophilic activation and Au(I)/Au(III) catalysis: an emerging technique for 1,2-difunctionalization of C-C multiple bonds

Gold complexes have emerged as the catalysts of choice for various functionalization reactions of C-C multiple bonds due to their inherent carbophilic nature. In a parallel space, efforts to realize less accessible cross-coupling reactivity have led to the development of various strategies that facilitate the arduous Au(i)/Au(iii) redox cycle. The interplay of the two important reactivity modes encountered in gold catalysis, namely carbophilic activation and Au(i)/Au(iii) catalysis, has allowed the development of a novel mechanistic paradigm that sponsors 1,2-difunctionalization reactions of various C-C multiple bonds. Interestingly, the reactivity as well as selectivity obtained through this interplay could be complementary to that obtained by the use of various other transition metals that mainly involved the classical oxidative addition/migratory insertion pathways. The present review shall comprehensively cover all the 1,2-difunctionalization reactions of C-C multiple bonds that have been realized by the interplay of the two important reactivity modes and categorized on the basis of the method that has been employed to foster the Au(i)/Au(iii) redox cycle.

Base-Free Cross-Couplings of Aryl Diazonium Salts in Methanol: PdII -Alkoxy as Reactivity-Controlling Intermediate

Pd-catalyzed cross-coupling reactions of aryl diazonium salts are generally assumed to proceed via cationic Pd^II intermediates which in turn would be highly reactive in the subsequent transmetalation step. Contrary to this belief, we herein report our observation and rationalization of opposing reactivities of ArN₂ ⁺ in Suzuki (=effective) and Stille (=ineffective) cross-couplings in MeOH. Our systematic experimental and computational studies on the roles of transmetalating agent, solvent, base and the likely involvement of in situ formed diazoether derivatives challenge the currently accepted mechanism. Our data suggest that the observed solvent dichotomy is primarily due to Pd^II -methoxy intermediates being formed, which are unreactive with arylstannanes, but highly reactive with arylboronic acids, complementing the Suzuki "Pd-oxy" mechanism with the direct demonstration of transmetalation of a Pd^II -alkoxy complex. Lewis acids were found to circumvent this reactivity divergence, promoting efficient couplings regardless of the employed conditions or coupling partners.

Alkyne Trifunctionalization via Divergent Gold Catalysis: Combining π-Acid Activation, Vinyl-Gold Addition, and Redox Catalysis

Here we report the first example of alkyne trifunctionalization through simultaneous construction of C-C, C-O, and C-N bonds via gold catalysis. With the assistance of a γ-keto directing group, sequential gold-catalyzed alkyne hydration, vinyl-gold nucleophilic addition, and gold(III) reductive elimination were achieved in one pot. Diazonium salts were identified as both electrophiles (N source) and oxidants (C source). Vinyl-gold(III) intermediates were revealed as effective nucleophiles toward diazonium, facilitating nucleophilic addition and reductive elimination with high efficiency. The rather comprehensive reaction sequence was achieved with excellent yields (up to 95%) and broad scope (>50 examples) under mild conditions (room temperature or 40 °C).

Supramolecular Gold Stripping from Activated Carbon Using α-Cyclodextrin

We report the molecular recognition of the Au(CN)₂^- anion, a crucial intermediate in today's gold mining industry, by α-cyclodextrin. Three X-ray single-crystal superstructures-KAu(CN)₂⊂α-cyclodextrin, KAu(CN)₂⊂(α-cyclodextrin)₂, and KAg(CN)₂⊂(α-cyclodextrin)₂-demonstrate that the binding cavity of α-cyclodextrin is a good fit for metal-coordination complexes, such as Au(CN)₂^- and Ag(CN)₂^- with linear geometries, while the K⁺ ions fulfill the role of linking α-cyclodextrin tori together as a result of [K⁺···O] ion-dipole interactions. A 1:1 binding stoichiometry between Au(CN)₂^- and α-cyclodextrin in aqueous solution, revealed by ¹H NMR titrations, has produced binding constants in the order of 10⁴ M^-1. Isothermal calorimetry titrations indicate that this molecular recognition is driven by a favorable enthalpy change overcoming a small entropic penalty. The adduct formation of KAu(CN)₂⊂α-cyclodextrin in aqueous solution is sustained by multiple [C-H···π] and [C-H···anion] interactions in addition to hydrophobic effects. The molecular recognition has also been investigated by DFT calculations, which suggest that the 2:1 binding stoichiometry between α-cyclodextrin and Au(CN)₂^- is favored in the presence of ethanol. We have demonstrated that this molecular recognition process between α-cyclodextrin and KAu(CN)₂ can be applied to the stripping of gold from the surface of activated carbon at room temperature. Moreover, this stripping process is selective for Au(CN)₂^- in the presence of Ag(CN)₂^-, which has a lower binding affinity toward α-cyclodextrin. This molecular recognition process could, in principle, be integrated into commercial gold-mining protocols and lead to significantly reduced costs, energy consumption, and environmental impact.

Homogeneous Gold Redox Chemistry: Organometallics, Catalysis, and Beyond

Gold redox chemistry holds the promise of unique reactivities and selectivities that are different to other transition metals. Recent studies have utilized strain release, ligand design, and photochemistry to promote the otherwise sluggish oxidative addition to Au(I) complexes. More details on the reductive elimination from Au(III) complexes have also been revealed. These discoveries have facilitated the development of gold redox catalysis and will continue to offer mechanistic insight and inspiration for other transition metals. This review highlights how research in organometallic chemistry has led to gold redox catalysis, as well as applications in materials science, bioconjugation, and radiochemical synthesis.

Stereoselective Formation of Facial Tris-Cyclometalated PtIV Complexes: Dual Phosphorescence from Heteroleptic Derivatives

A stereoselective synthetic route to homo- and heteroleptic facial tris-cyclometalated Pt^IV complexes is reported, involving the oxidative addition of 2-(2-pyridyl)- or 2-(1-isoquinolinyl)benzenediazonium salts to cis-[Pt(C^N)₂ ] precursors, with C^N=cyclometalated 2-(p-tolyl)pyridine (tpy), 2-phenylquinoline (pq), 2-(2-thienyl)pyridine or 1-phenylisoquinoline (piq), to produce labile diazenide intermediates that undergo photochemical or thermal elimination of N₂ . The method allows the preparation of derivatives bearing cyclometalated ligands of low π-π* transition energies. The new complexes exhibit phosphorescence in fluid solution at room temperature arising from triplet ligand-centered (³ LC) excited states, which, in the cases of the heteroleptic derivatives, involve the ligand with the lowest π-π* gap. The heteroleptic piq derivatives exhibit fluorescence and dual phosphorescence from different ligand-centered excited states in rigid media, demonstrating the potential of cyclometalated Pt^IV complexes as multi-emissive materials.

Synthesis of Carbazoles and Related Heterocycles from Sulfilimines by Intramolecular C-H Aminations

While direct nitrene insertions into C-H bonds have become an important tool for building C-N bonds in modern organic chemistry, the generation of nitrene intermediates always requires transition metals, high temperatures, ultraviolet or laser light. We report a mild synthesis of carbazoles and related building blocks through a visible light-induced intramolecular C-H amination reaction. A striking advantage of this new method is the use of more reactive aryl sulfilimines instead of the corresponding hazardous azides. Different catalysts and divergent light sources were tested. The reaction scope is broad and the product yield is generally high. An efficient gram-scale synthesis of Clausine C demonstrates the applicability and scalability of this new method.

Gold Redox Catalysis with a Selenium Cation as a Mild Oxidant

Gold-catalyzed alkyne and allene diselenations were developed. Excellent regioselectivity (trans) and good to excellent yields were achieved (up to 98 % with 2 % catalyst loading) with a wide range of substrates. Mechanistic investigation revealed the formation of a vinyl gold(I) intermediate followed by an intermolecular selenium cation migration, suggesting that a gold(I/III) redox process was successfully implemented under mild conditions.

Synthesis of Fulvene Vinyl Ethers by Gold Catalysis

Gold-catalyzed cyclization of 1,5-diynes with ketones as reagents and solvent provides diversely substituted vinyl ethers under mild conditions. The regioselectivity of such gold-catalyzed cyclizations is usually controlled by the scaffold of the diyne. Herein, we report the first solvent-controlled switching of regioselectivity from a 6-endo-dig- to 5-endo-dig-cyclization in these transformations, providing fulvene derivatives. With respect to the functional-group tolerance, aryl fluorides, chlorides, bromides, and ethers are tolerated. Furthermore, the mechanism and selectivity are put to scrutiny by experimental studies and a thermodynamic analysis of the product. Additionally, 6-(vinyloxy)fulvenes are a hitherto unknown class of compounds. Their reactivity is briefly evaluated, to give insights into their potential applications.

Mild and Efficient Synthesis of Diverse Organo-AuI -L Complexes in Green Solvents

An exceptionally mild and efficient method was developed for the preparation of (hetero)aryl-Au^I -L complexes using ethanol or water as the reaction medium at room temperature and Ar-B(triol)K boronates as the transmetalation partner. The reaction does not need an exogeneous base or other additives, and quantitative yields can be achieved through a simple filtration as the only required purification method, which obviates considerable waste associated with alternative workup methods. A broad reaction scope was demonstrated with respect to both the L and (hetero)aryl ligands on product Au complexes. Despite the polar reaction medium, large polycyclic aromatic hydrocarbon units can be incorporated on the Au complexes in very good to excellent yields. The approach was demonstrated for the chemoselective manipulation of orthogonally protected aryl boronates to afford a new class of N-heterocyclic carbene-Au-aryl complexes. A mechanistic rationale was proposed.

Mercury-Free Synthesis of Pincer [C^N^C]AuIII Complexes by an Oxidative Addition/CH Activation Cascade

Starting from the commercially available dimethyl sulfide-gold(I) chloride complex (DMSAuCl) and diazonium salts in the presence of 2,6-di-tert-butyl-4-methylpyridine as base, symmetric and unsymmetric [C^N^C]Au^III Cl complexes were synthesized in a selective, photosensitizer-free, photochemical reaction using blue LED light. This new protocol provides the first mercury-free synthesis of these types of pincer-complexes in moderate-to-excellent yields, starting from a readily available gold(I) precursor. Owing to the extraordinary properties of the target compounds, like excellent luminescence and high anticancer activities, the synthesis of such complexes is a highly active field of research, which might make its way to an industrial application. Owing to the disadvantages of the known protocols, especially the toxicity and the selectivity issues in the case of unsymmetric complexes, avoiding the use of mercury, should further accelerate this ongoing development.

Gold-catalyzed domino cyclization enabling construction of diverse fused azaspiro tetracyclic scaffolds: a cascade catalysis mechanism due to a substrate and counterion

The detailed mechanism and origins of gold-catalyzed domino cyclization to diverse fused azaspiro tetracyclic scaffolds by cooperative dual catalysis and cascade catalysis are systematically studied.

A highly stable, Au/Ru heterobimetallic photoredox catalyst with a [2.2]paracyclophane backbone

We report the synthesis and catalytic application of a highly stable distance-defined Au/Ru heterobimetallic complex. [2.2]Paracyclophane serves as a backbone, holding the two metal centers in a spatial orientation and metal-metal fixed distance. The Au/Ru heterobimetallic complex is highly stable, easily accessible and exhibits promising catalytic activity in a visible-light mediated dual Au/Ru Meyer-Schuster rearrangement.