Cationic Au<sup>III</sup> versus Au<sup>I</sup>: Catalyst‐Controlled Divergent Reactivity of Alkyne‐Tethered Lactams

Alcaide, Benito; Almendros, Pedro; Cembellín, Sara; Fernández, Israel; Campo, Teresa Martínez del

doi:10.1002/chem.201700234

Cited by 14 publications

(12 citation statements)

References 37 publications

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“…Another striking case was reported by Alcaide et al, who investigated the reactivity of alkyne-tethered lactams 316 in the presence of well-defined Au(I) and Au(III) catalysts. 531 Here, while (IPr)Au(I) salts afforded mixture of 7-and 8-membered carbocyclization products 317 and 318, the biphenyldiyl chelate (C^C)Au(IPr)Cl 133 led to the exclusive formation of a bridged oxa-azabicyclo[4.2.1]nonenone 319 (Scheme 135). Mechanistic studies revealed that the Au(III) catalyst formed selectively 317 as an intermediate and catalyzed a further rearrangement to the bridged product 319.…”

Section: Lewis Acid Catalysis By Gold(iii)mentioning

confidence: 99%

Recent Advances in Gold(III) Chemistry: Structure, Bonding, Reactivity, and Role in Homogeneous Catalysis

2020

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Over the last decade the organometallic chemistry of gold(III) has seen remarkable advances. This includes the synthesis of the first examples of several compound classes that have long been hypothesized as being part of catalytic cycles, such as gold(III) alkene, alkyne, CO and hydride complexes, and important catalysis-relevant reaction steps have at last been demonstrated for gold, such as migratory insertion and β-H elimination reactions. Also, reaction pathways that were already known, such as the generation of gold(III) intermediates by oxidative addition and their reductive elimination, are much better understood. A deeper understanding of fundamental organometallic reactivity of gold(III) has also revealed unexpected mechanistic avenues, which can open when the barriers for reactions that for other metals would be regarded as "standard" are too high. This review summarizes and evaluates these developments, together with applications of gold(III) in synthesis and catalysis, with emphasis on the mechanistic insight gained in these investigations.

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Section: Lewis Acid Catalysis By Gold(iii)mentioning

confidence: 99%

Recent Advances in Gold(III) Chemistry: Structure, Bonding, Reactivity, and Role in Homogeneous Catalysis

2020

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“…Available methodologies including the catalyst-controlled reactivity of (indolyl)alkyne-tethered lactams 169 173 Cyclization precursors consisting of enantiopure alkynyloxazolidine-tethered 2-azetidones 167 were transformed into annulated β-lactams 168 chemoselectively under mild conditions employing gold catalysis, Scheme 45. Nonterminal alkynes delivered the desired bicyclic compounds without deleterious effects on the sensitive four-membered lactam ring.…”

Section: Vinylidenecyclopropanes As Nucleophilementioning

confidence: 99%

Construction of Medium-Sized Rings by Gold Catalysis

2020

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Compounds having cyclic molecular frameworks are highly regarded for their abundance and diverse utilities. In particular, medium-sized carbocycles and heterocycles exist in a broad spectrum of natural products, bioactive therapeutics, and medicinally significant synthetic molecules. Metal-mediated methods have been developed for the preparation of compounds containing a medium-sized ring (MSR) through cyclization of different classes of substrates and acyclic precursors. This review focuses on the methodologies for construction of MSRs via gold catalysis. Given the challenges in enabling the assembly of different ring sizes, we present here accounts on Au-mediated cyclization giving notable 7-membered and medium-sized (8–11-membered ring) structures. Emphasis on the pathway and mode of cyclization and the selection of precursors ranging from structurally biased compounds were outlined. Reactivity patterns and the choice of efficient Au catalysts for controlling reaction performance and selectivity in addition to mechanistic attributes are examined.

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“…As shown in Scheme 101, allenyl-β-lactams 627 were found to undergo a gold(I)-catalyzed fragmentation reaction toward strained caged structures 628 in moderate to good yields but as a single diastereomer. 161 The authors pointed out that some of the lower yields were likely due to decomposition of the sensitive 162 Through a combination of deuterium-labeling studies and DFT calculations, a detailed mechanism for the transformation was proposed. The reaction proceeds through a 7-exo-carboauration of gold-coordinated 637 to give vinyl-gold species 638, a formal hydroarylation reaction.…”

Section: Gold-catalyzed Reactions Of Aryl Vinyl and Alkyl Aziridinesmentioning

confidence: 99%

“…Alcaide, Almendros, and co-workers have investigated the gold-catalyzed reactivity of a range of β-lactams bearing alkynyl- and allenyl-tethers. − In many of these reactions, the β-lactam ring is incidental to the gold catalyzed reactivity, therefore only the examples where the ring itself participates in a gold-catalyzed reaction will be discussed in detail here.…”

Section: Gold-catalyzed Reactions Of Strained N-containing Heterocyclesmentioning

confidence: 99%

“…Alcaide and Almendros also investigated the gold-catalyzed reactivity of alkyne-tethered β-lactams 634 , which in the presence of the stable gold(III)-catalyst precursor 635 gave bridged oxa-azabicyclo[4.2.1]nonenone 636 (Scheme ). Through a combination of deuterium-labeling studies and DFT calculations, a detailed mechanism for the transformation was proposed. The reaction proceeds through a 7- exo -carboauration of gold-coordinated 637 to give vinyl-gold species 638 , a formal hydroarylation reaction.…”

Section: Gold-catalyzed Reactions Of Strained N-containing Heterocyclesmentioning

confidence: 99%

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Gold-Catalyzed Conversion of Highly Strained Compounds

et al. 2020

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The past decade has witnessed the golden age of homogeneous gold-catalyzed reactions, especially those that involve the transformation of highly strained molecules into complex molecular architectures. Gold catalysts, with unique electronic properties and catalytic abilities, have elevated versatile reaction modes through π-interaction induced activation. On the basis of increasing research interest in this topic, together with the significant development of various ligands, including phosphine ligands and azacyclic or noncyclic carbene ligands, the understanding of the catalytic function of gold catalysts has become much deeper and more comprehensive. Different reaction needs thus could be adapted by a novel gold catalyst with a diversified ligand selection. Furthermore, the whole evolution of the gold catalysis on synthetic methodologies has realized and expanded its application into natural product synthesis as well as the potentiality of drug discovery, which endows this ancient metal with a magnificent renaissance. The reactivity of strained small ring molecules with high tension has always been an important research topic in organic chemistry. When the highly strained small ring is linked with a π-electron rich moiety or contains a heteroatom, the gold activation of the π-system or coordination with the heteroatom can initiate a cascade reaction, usually followed by ring opening or expansion. These processes can result in the rapid construction of complex and distinct molecular structures, many of which feature in biologically important molecules. In this review, we will mainly summarize the advances on diverse reaction types and molecular constructions accomplished by homogeneous gold catalysis using highly strained substrates, including methylenecyclopropanes (MCPs), vinylidenecyclopropanes (VDCPs), cyclopropenes as well as aziridine- and epoxide-containing molecules, focusing on the last 10 years. For functionalized alkynyl cyclopropanes, several early inspiring and elegant examples will be described in this review for systematically understanding these transformations.

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Cationic Au^III versus Au^I: Catalyst‐Controlled Divergent Reactivity of Alkyne‐Tethered Lactams

Abstract: Switchable reactivity through cationic gold‐based catalyst control built on the oxidation state, namely cationic AuIII versus AuI, has been achieved in the direct functionalization of 2‐azetidinone‐tethered alkynyl indoles.

Cited by 14 publications

References 37 publications

Recent Advances in Gold(III) Chemistry: Structure, Bonding, Reactivity, and Role in Homogeneous Catalysis

Recent Advances in Gold(III) Chemistry: Structure, Bonding, Reactivity, and Role in Homogeneous Catalysis

Construction of Medium-Sized Rings by Gold Catalysis

Gold-Catalyzed Conversion of Highly Strained Compounds

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Cationic AuIII versus AuI: Catalyst‐Controlled Divergent Reactivity of Alkyne‐Tethered Lactams

Abstract: Switchable reactivity through cationic gold‐based catalyst control built on the oxidation state, namely cationic AuIII versus AuI, has been achieved in the direct functionalization of 2‐azetidinone‐tethered alkynyl indoles.

Cited by 14 publications

References 37 publications

Recent Advances in Gold(III) Chemistry: Structure, Bonding, Reactivity, and Role in Homogeneous Catalysis

Recent Advances in Gold(III) Chemistry: Structure, Bonding, Reactivity, and Role in Homogeneous Catalysis

Construction of Medium-Sized Rings by Gold Catalysis

Gold-Catalyzed Conversion of Highly Strained Compounds

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Product

Resources

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Cationic Au^III versus Au^I: Catalyst‐Controlled Divergent Reactivity of Alkyne‐Tethered Lactams