Search

A catalytic method to synthesize a broad array of cyclometalated (C^N)gold(III) complexes is reported here. An unprecedented Rh-to-Au

Photoredox and Ni catalysis are combined to produce diaryl ethers under mild conditions. A broad range of aryl halides and phenol derivatives are cross-coupled in the presence of a readily availabl...

The potential of merging photoredox and nickel catalysis to perform multicomponent alkene difunctionalizations under visible-light irradiation is demonstrated here. Secondary and tertiary alkyl groups, as well as sulfonyl moieties can be added to the terminal position of the double bond with simultaneous arylation of the internal carbon atom in a single step under mild reaction conditions. The process, devoid of stoichiometric additives, benefits from the use of bench-stable and easy-to-handle reagents, is operationally simple, and tolerates a wide variety of functional groups.

The mechanism of the gold-catalyzed oxidative cross-coupling of arenes and alkynes has been studied in detail combining stoichiometric experiments with putative reaction intermediates and DFT calculations., The mechanism of the gold-catalyzed oxidative cross-coupling of arenes and alkynes has been studied in detail combining stoichiometric experiments with putative reaction intermediates and DFT calculations. Our data suggest that ligand exchange between the alkyne, the Au(i)-catalyst and the hypervalent iodine reagent is responsible for the formation of both an Au(i)-acetylide complex and a more reactive “non-symmetric” I(iii) oxidant responsible for the crucial Au(i)/Au(iii) turnover. Further, the reactivity of the in situ generated Au(iii)-acetylide complex is governed by the nature of the anionic ligands transferred by the I(iii) oxidant: while halogen ligands remain unreactive, acetato ligands are efficiently displaced by the arene to yield the observed Csp2–Csp cross-coupling products through an irreversible reductive elimination step. Finally, the nature of competitive processes and catalyst deactivation pathways has also been unraveled. This detailed investigation provides insights not only on the specific features of the species involved in oxidative gold-catalyzed cross couplings but also highlights the importance of both ancillary and anionic ligands in the reactivity of the key Au(iii) intermediates.

A nickel-catalyzed asymmetric reductive hydroarylation of vinyl amides to produce enantioenriched α-arylbenzamides is reported. The use of a chiral bisimidazoline (BIm) ligand, in combination with diethoxymethylsilane and aryl halides, enables the regioselective introduction of aryl groups to the internal position of the olefin, forging a new stereogenic center α to the N atom. The use of neutral reagents and mild reaction conditions provides simple access to pharmacologically relevant motifs present in anticancer, SARS-CoV PLpro inhibitors, and KCNQ channel openers.

Pyridine-substituted alkylidenecyclopropanes (Py-ACPs) react with gold(III) salts under mild reaction conditions through an unprecedented, proximal ring-opening pathway, to generate highly appealing, catalytically active pyridine alkenyl [C^N]-gold(III) species. Mechanistic studies reveal that the activation of the C−C bond of the ACP takes place through an unusual concerted, σ-bond metathesis type-process., We thank the European Research Council (ERC Starting grant agreement no.307948, and Advanced Grant 340055), the Swiss National Science Foundation (SNF 200020_146853), the Legerlotz Stiftung the MINECO (SAF2016-76689-R, CTQ2017-84767-P), the Xunta de Galicia (2015-CP082, ED431C 2017/19, and Centro singular de investigación de Galicia accreditation 2019–2022, ED431G 2019/03) and the European Union (European Regional Development Fund— ERDF) for financial support and the STSM Grant to F. Verdugo from COST Action CA15106. We also thank Prof. Anthony Linden for the X-ray diffraction analysis of com- plexes 1a’ ’ (CCDC 1984877), 2a (CCDC 1984881), 2b (CCDC 1984883), 3c (CCDC 1984885), 3c’’’’ (CCDC 2004632) and 4a (CCDC 1984886).

A new family of cationic, bidentate (P^N)gold(III) fluoride complexes has been prepared and a detailed characterization of the gold‐fluoride bond has been carried out. Our results correlate with the observed reactivity of the fluoro ligand, which undergoes facile exchange with both cyano and acetylene nucleophiles. The resulting (P^N)arylgold(III)C(sp) complexes have enabled the first study of reductive elimination on (P^N)gold(III) systems, which demonstrated that C(sp2)−C(sp) bond formation occurs at higher rates than those reported for analogous phosphine‐based monodentate systems.

This paper describes an efficient aminoesterification of unactivated alkenes through Au(I)/Au(III) redox catalytic cycles using Selectfluor or hypervalent iodine(III) reagents.

The first stable gold(III) formate and experimental evidence for its β-hydride elimination are described. A catalytic dehydrogenation of formic acid together with mechanistic studies shed light on potential pathways operating in fundamental gold-catalyzed transformations.

An intermolecular, three-component reductive dicarbofunctionalization of alkenes is presented here. The combination of Ni catalysis with TDAE as final reductant enables the direct formation of Csp3–Csp3 and Csp3–Csp2 bonds across a variety of π-systems using two different electrophiles that are sequentially activated with exquisite selectivity under mild reaction conditions.

A redox-neutral, light-mediated functionalization of unactivated C(sp3 )-H bonds via iminyl radicals is presented here. A 1,5-H transfer followed by the functionalization of a C(sp2 )-H bond takes place in aqueous media producing a variety of elaborated fused ketones. Mechanistic investigations have revealed 1,5-H transfer as the reversible, rate-determining step in this transformation. Divergent scaffolds are also accessible via C(sp3 )-N bond formation upon a careful choice of the reaction additives.

An efficient synthesis of biaryls through a gold-catalyzed oxidative cross-coupling of arenes with strong electron-deprived aryl boronates is presented herein. Regio- and chemocontrol are achieved by the selective activation of these coupling partners by gold at different oxidation states. Under reaction conditions devoid of basic additives or directing groups, the role of acetato ligand as an internal base has been revealed as a key parameter for expanding the reaction scope in these transformations.

Olefins devoid of directing or activating groups have been dicarbofunctionalized here with two electrophilic carbon sources under reductive conditions. Simultaneous formation of one C(sp3)-C(sp3) and one C(sp3)-C(sp2) bond across a variety of unbiased π-systems proceeds with exquisite selectivity by the combination of a Ni catalyst with TDAE as sacrificial reductant. Control experiments and computational studies revealed the feasibility of a radical-based mechanism involving, formally, two interconnected Ni(I)/Ni(III) processes and demonstrated the different ability of Ni(I) species (Ni(I)I vs PhNi(I)) to reduce the C(sp3)-I bond. The role of the reductant was also investigated in depth, suggesting that a one-electron reduction of Ni(II) species to Ni(I) is thermodynamically favored. Further, the preferential activation of alkyl vs aryl halides by ArNi(I) complexes as well as the high affinity of ArNi(II) for secondary over tertiary C-centered radicals explains the lack of undesired homo- and direct coupling products (Ar-Ar, Ar-Alk) in these transformations.

Synergistic gold-palladium catalytic processes have been intensively sought during the past decade, because the combination of the carbophilic Lewis acidity of Au with the redox properties of Pd within a catalytic cycle is particularly appealing for the synthesis of novel functionalized compounds. We demonstrate here the feasibility of a Au-Pd bimetallic catalytic system based on the generation of competent Au and Pd species by anionic ligand exchange. This strategy enabled the preparation of a variety of substituted butenolides in a simple and efficient way.

Herein we present the first example of a three-component dicarbofunctionalization of olefins under reductive conditions. Our strategy takes advantage of nickel catalysis to add aryl and alkyl groups across the double bond with remarkable selectivity. The reaction shows broad functional group compatibility and more importantly, it proves to be general in terms of the alkenes that can be functionalized compared to previous dicarbofunctionalization methods. Initial control experiments reveal different activation modes for both electrophiles and the involvement of alkyl radicals throughout the reaction.

A Pd-catalyzed three component reaction involving terminal alkynes, boronic acids, and perfluoroalkyl iodides is presented here. Trisubstituted perfluoroalkenes can be obtained in a highly regio- and stereocontrolled manner by the simultaneous addition of both aryl and CnFm groups across the triple bond in a radical-mediated process. The reaction is operationally simple offering a broad scope and functional group tolerance.

Cleavage of unstrained C−C bonds under mild, redox-neutral conditions represents a challenging endeavor which is accomplished here in the context of a flexible, visible-light-mediated, γ-functionalization of amines. In situ generated C-centered radicals are harvested in the presence of Michael acceptors, thiols and alkyl halides to efficiently form new C(sp3)−C(sp3), C(sp3)−H and C(sp3)−Br bonds, respectively.

A Pd-catalyzed difunctionalization of internal alkynes combining boronic acids and perfluoroalkyl iodides under mild conditions is described here. Tetrasubstituted olefins containing perfluoroalkyl groups are synthesized in high yields in a regio- and stereoselective manner. Mechanistic studies have been carried out to shed light on the nature of the likely intermediates involved in these transformations.

The underlying reactivity of AuIII–F species with aryl boronic acids has been studied in detail taking advantage of four novel, stable difluoro-[(C^N)AuF2], arylmonofluoro-[(C^N)AuArF], and alkylmonofluoro-[(C^N)AuAlkF] gold(III) complexes, prepared and isolated in monomeric form. We provide the first experimental evidence for a direct AuIII–F/B transmetalation preceding the Csp2–Csp2 or Csp3–Csp2 bond formation.

This Review showcases the ability of bi- and tridentate ligands to stabilize gold in high oxidation states through the formation of mono- and biscyclometalated gold(III) complexes. In-depth studies on the synthesis, intrinsic reactivity, catalytic relevance, and photophysical properties of stabilized gold(III) species have been carried out, setting the stage for exciting developments in various research areas, such as catalysis, inorganic and bioinorganic chemistry, ligand design, and materials science.

We report the design, synthesis, and application of a (N^C^C)-ligand framework able to stabilize highly electron-deprived gold(III) species. This novel platform enabled the preparation of C(sp(2))-gold(III) fluorides for the first time in monomeric, easy-to-handle, bench-stable form by a Cl/F ligand-exchange reaction. Devoid of oxidative conditions or stoichiometric use of toxic Hg salts, this method was applied to the preparation of multiple [C(sp(2))-Au(III)-F] complexes, which were used as mechanistic probes for the study of the unique properties and intrinsic reactivity of Au-F bonds. The improved photophysical properties of [(N^C^C)Au(III)] complexes compared to classical pincer (C^N^C)-Au systems paves the way for the design of new late-transition-metal-based OLEDs.

Two highly stereoselective radical-mediated syntheses of densely functionalized indanes and dibenzocycloheptadienes from ortho-vinyl- and ortho-vinylaryl-substituted N-(arylsulfonyl)-acrylamides, respectively, are presented here. The chemoselective addition of in situ generated radicals (X(·)) onto the styrene moieties triggers an unprecedented reaction cascade, resulting in the formation of one new C-X bond and two new C-C bonds, a formal 1,4-aryl migration, and the extrusion of SO2 to generate an amidyl radical intermediate. This intermediate, upon H abstraction, leads to the observed 5- and 7-membered ring carbocyclic products, respectively, in a highly efficient manner.