Gold(I)‐Catalyzed Synthesis of Indenes and Cyclopentadienes: Access to (±)‐Laurokamurene B and the Skeletons of the Cycloaurenones and Dysiherbols

Yin, Xiang; Mato, Mauro; Echavarren, Antonio M.

doi:10.1002/ange.201708947

Cited by 31 publications

(14 citation statements)

References 78 publications

(32 reference statements)

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“…Mechanism of tethered substrate. We began our mechanistic incursions with the mechanism of Aucatalyzed cyclization of tethered acetal 2-alkynylaldehyde (1a) to form 2-(4-methoxyphenyl)spiro[indene-1,2'- [1,3]dioxolane] (2a) ( Figure 2). The reaction overall composes of five important steps; Au insertion, 1,5-shift, cyclization, 1,2-shift and elimination.…”

Section: Resultsmentioning

confidence: 99%

“…Indenones represent common motifs of carbocycles with a prime of importance in many structurally complex bioactive compounds or natural products. 1 Several synthetic methods of indenone have been shown to give moderate selectivities and yields using gold catalysis, 2,3 iodine-mediated strategy, 4 and organolithium reagents. 5 Therefore, advancing a catalytically efficient approach has motivated and attracted many synthetic groups by which a metal-catalyzed cyclization was a premier rout being targeted.…”

Section: Introductionmentioning

confidence: 99%

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Revealing Mechanism and Origin of Reactivity of Au(I)-Catalyzed Functionalized Indenone Formation of Cyclic and Acyclic Acetals of Alkynylaldehydes

Hussein

Ali²

2020

Preprint

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<p><a>Density functional theory exploited with the (SMD)-B3LYP-D3/def2-TZVP//B3LYP/6-31G(d),LANL2DZ level of theory is presented to offer mechanistic insights and explications of experimentally intriguing observations in the Au(I)-catalyzed cyclization of cyclic and acyclic acetals of alkynylaldehydes that lead to indenone formation. The reactivity of catalytic cycles with and without methoxy migration is computationally defined when alkyne terminus is phenylated in addition to the unreactive cycle when alkyne terminus is not phenylated. The reaction mechanism of indenone formation proceeds first with coordination of Au(I) to alkyne to initiate the reaction with 1,5-H shift as a rate-determining step and the fastest 1,5-H shift is achieved when one phenyl ring carries electron-donating group and the other one is substituted with electron-withdrawing group. The absence of tethered acetal unit considerably outpaces any 1,5-H shift and instead activates 1,5-methoxy migration, giving methoxy-migrated indenone, with the step of 1,2-OMe shift is a rate-limiting step during reaction pathway. Following 1,5-H shift the cyclization and 1,2-H shift are kinetically and thermodynamically feasible, which are followed by elimination to persist the iterative cycle, but the reactivity of both steps is highly affected by the existence of phenyl group on alkyne terminus. The unreactivity of alkyne terminus being not beared a phenyl ring is due to that the cyclization is thermodynamically disfavorable, subsequently deactivating the 1,2-H shift kinetically and thermodynamically. </a></p>

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Revealing Mechanism and Origin of Reactivity of Au(I)-Catalyzed Functionalized Indenone Formation of Cyclic and Acyclic Acetals of Alkynylaldehydes

Hussein

Ali²

2020

Preprint

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“…Cyclopropanation of olefins with a variety of carbene precursors, including diazo compounds, 1, n -enynes, yne-enones, propargyl esters, cyclopropenes, 1,3,5-cycloheptatrienes, and alkynes via oxidation/nitrene transfer processes, is the main focus in this area 36 . Gold-catalyzed [4 + 1]- 37 and [3 + 2]-cycloadditions 38 , 39 have been disclosed by Echavarren with 1,3,5-cycloheptatriene as the carbene precursor. Meanwhile, the gold-catalyzed formal [4 + 2]-cyclization of enynes with tethered alkene via cyclopropyl metal carbene intermediate has been studied by the same group 40 .…”

Section: Introductionmentioning

confidence: 99%

Gold(I)-catalyzed intramolecular cyclization/intermolecular cycloaddition cascade as a fast track to polycarbocycles and mechanistic insights

et al. 2021

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Metal carbene is an active synthetic intermediate, which has shown versatile applications in synthetic chemistry. Although a variety of catalytic methods have been disclosed for the generation of carbene species from different precursors, there is an increasing demand for the development of efficient and practical approaches for the in-situ formation of metal carbene intermediates with structural diversity and unrevealed reactivity. Herein we report a gold-catalyzed cascade protocol for the assembly of polycarbocyclic frameworks in high yields under mild reaction conditions. Mechanistic studies indicate that the unique β-aryl gold-carbene species, generated via gold-promoted 6-endo-dig diazo-yne cyclization, is the key intermediate in this reaction, followed by a [4 + 2]-cycloaddition with external alkenes. In comparison to the well-documented metal carbene cycloadditions, this carbene intermediate serves as a 4-C synthon in a cycloaddition reaction. A variety of elusive π-conjugated polycyclic hydrocarbons (CPHs) with multiple substituents are readily accessible from the initially generated products by a mild oxidation procedure.

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“…Cyclopropanation of ole ns with a variety of carbene precursors, including diazo compounds, 1,n-enynes, yne-enones, propargyl esters, cyclopropenes, 1,3,5-cycloheptatrienes, and alkynes via oxidation/nitrene transfer processes, is the main focus in this area 35 . Gold-catalyzed [4+1]- 36 and [3+2]cycloadditions 37,38 have been disclosed by Echavarren with 1,3,5-cycloheptatriene as the carbene precursor. Meanwhile, the gold-catalyzed formal [4+2]-cyclization of enynes with tethered alkene via cyclopropyl metal carbene intermediate has been studied by the same group 39 .…”

Section: Introductionmentioning

confidence: 99%

Gold(I)-Catalyzed Intramolecular Cyclization/Intermolecular Cycloaddition Cascade: Fast Track to Polycarbocycles and Mechanistic Insights

Zhang¹,

Hong²,

Pei³

et al. 2020

Preprint

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Herein we report a gold-catalyzed cascade protocol for the assembly of polycarbocyclic frameworks in high yields under mild reaction conditions. Mechanistic studies indicate that the unique β-aryl gold-carbene species, generated via gold-promoted 6-endo-dig diazo-yne cyclization, is the key intermediate in this reaction, followed by a [4 + 2]-cycloaddition with external alkenes. In comparison to the well-documented metal carbene cycloadditions, this is the first example of the carbene intermediate to serve as a 4-C synthon in a cycloaddition reaction. A variety of elusive π-conjugated polycyclic hydrocarbons (CPHs) with multiple substituents are readily accessible from the initially generated products by a mild oxidation procedure.

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Gold(I)‐Catalyzed Synthesis of Indenes and Cyclopentadienes: Access to (±)‐Laurokamurene B and the Skeletons of the Cycloaurenones and Dysiherbols

Cited by 31 publications

References 78 publications

Revealing Mechanism and Origin of Reactivity of Au(I)-Catalyzed Functionalized Indenone Formation of Cyclic and Acyclic Acetals of Alkynylaldehydes

Revealing Mechanism and Origin of Reactivity of Au(I)-Catalyzed Functionalized Indenone Formation of Cyclic and Acyclic Acetals of Alkynylaldehydes

Gold(I)-catalyzed intramolecular cyclization/intermolecular cycloaddition cascade as a fast track to polycarbocycles and mechanistic insights

Gold(I)-Catalyzed Intramolecular Cyclization/Intermolecular Cycloaddition Cascade: Fast Track to Polycarbocycles and Mechanistic Insights

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