Non‐Canonical Reactivity of Gold Carbene with Alkyne: An Overview of the Mechanistic Premise

European Journal of Organic Chemistry, Journal Year: 2021, Volume and Issue: 2021(9), P. 1321 - 1330

Published: Jan. 16, 2021

Abstract The unique nature of gold carbene and its synchronous counterpart gold‐stabilized carbocation, is mainly responsible for the non‐canonical reactivity profile that it demonstrates in comparison to any other transition metal carbene. Being an important subset this class, reactions with alkyne sponsor products far more diverse than cyclopropenation as canonically expected case carbenes. These gold‐catalyzed have largely been proposed follow either a [1,n]‐carbene transfer process or alternate pathway involving direct interception β‐gold vinyl cation nucleophile at cationic carbon. Despite clear distinction structure, bonding energy cation; they found exhibit identical reactivities like cyclopropenation, C(sp 2 )–H insertion, etc. making extremely difficult “experimentally” investigate validate mechanistic pathway. It because lack conclusive experimental evidence, addition limited number detailed computational studies, multiple pathways simultaneously rationalize product formation. As effort shed light on mechanisms these reactions, herein, documentation focus their premise has presented.

Language: Английский

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Enantioselective Indole Insertion Reactions of α-Carbonyl Sulfoxonium Ylides

Organic Letters, Journal Year: 2021, Volume and Issue: 23(24), P. 9446 - 9450

Published: Dec. 2, 2021

The first example of organocatalytic enantioselective C–H insertion reactions indoles and sulfoxonium ylides is reported. Under the influence phosphoric acid catalysis, levels enantiocontrol in range 20–93% ee moderate yields (up to 50%) were achieved for 29 examples formal free α-carbonyl ylides. No nitrogen protection on indole necessary.

Language: Английский

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Efficient Synthesis of Diaryl Quaternary Centers by Rh(II)/Xantphos Catalyzed Relay C−H Functionalization and Allylic Alkylation

Chemistry - A European Journal, Journal Year: 2022, Volume and Issue: 29(3)

Published: Oct. 14, 2022

A three-component reaction of N, N-disubstituted aniline, α-diazo ester, and an allylic electrophile has been realized by [Rh(II)]2 /Xantphos catalysis, providing a direct access to various aniline derivatives bearing diaryl quaternary centers in good yields. The synthetic utility this protocol was demonstrated facile derivatization the products for preparation biologically relevant molecules structural scaffolds, which offers high potential increasing molecular diversity. Mechanistic studies identified α, α-diarylacetate species as active intermediate, thereby revealing presence C(sp2 )-H functionalization derivatives/allylic alkylation cascade attractive catalytic transformation.

Language: Английский

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Asymmetric Arylation of Diazoesters with Anisoles Enabled by Cooperative Gold and Phosphoric Acid Catalysis

Organic Letters, Journal Year: 2022, Volume and Issue: 24(15), P. 2809 - 2814

Published: April 8, 2022

An enantioselective insertion of a carbene into the Csp2-H bond anisole derivatives has been accomplished using an achiral gold complex and chiral phosphoric acid as catalytic system, providing novel protocol for synthesis α,α-diaryl acetates. Density functional theory calculations reveal reactivity origin enantioselectivity this reaction.

Language: Английский

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Mechanism and stereoselectivity in metal and enzyme catalyzed carbene insertion into X–H and C(sp²)–H bonds

Chemical Society Reviews, Journal Year: 2024, Volume and Issue: 53(22), P. 11004 - 11044

Published: Jan. 1, 2024

This review provides a mechanistic overview of asymmetric Fe, Cu, Pd, Rh, Au and heme-based enzymes catalyzed carbene insertion reactions to construct C–X (X = O, N, S, etc. ) C–C bonds, focusing on the stereochemical models.

Language: Английский

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Multi C−H Functionalization Reactions of Carbazole Heterocycles via Gold‐Catalyzed Carbene Transfer Reactions

Chemistry - A European Journal, Journal Year: 2020, Volume and Issue: 27(8), P. 2628 - 2632

Published: Dec. 5, 2020

Abstract Herein we describe a multiple C−H functionalization reaction of carbazole heterocycles with diazoalkanes. We show that gold catalysts play distinct role in enabling to introduce up six carbene fragments onto molecules containing units or link into single molecule. A one‐pot stepwise approach enables the introduction two different allow orthogonal deprotection and straightforward derivatization.

Language: Английский

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Gold-Catalyzed Sigmatropic Rearrangement Reactions via Carbene Transfer Reactions

The Journal of Organic Chemistry, Journal Year: 2020, Volume and Issue: 85(18), P. 11882 - 11891

Published: Aug. 24, 2020

Sigmatropic rearrangements are an important fundamental toolbox in organic synthesis to access complex molecular fragments. Yet, the rearrangement reactions of onium ylides via gold catalyzed carbene transfer relatively unexplored. Herein, we describe a gold-catalyzed sigmatropic sulfonium and selenium (39 examples, up 99% yield). Furthermore, report on limitations aryl allyl anilines, which deliver exclusively C–H functionalized products.

Language: Английский

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Does an Enol Pathway Preclude High Stereoselectivity in Iron-Catalyzed Indole C–H Functionalization via Carbene Insertion?

The Journal of Organic Chemistry, Journal Year: 2022, Volume and Issue: 87(12), P. 7919 - 7933

Published: June 2, 2022

C–H functionalization of indoles via Fe carbenoids presents an attractive strategy to obtain biologically important structural motifs. However, obtaining good stereoselectivity with has been a significant challenge. It is unclear whether the low selectivity due radical pathway or ionic mechanism involving metal-free species. We therefore present density functional theory (DFT) study indole alkylation diazoacetates catalyzed by Fe(ClO4)TMEDA/spirobisoxazoline and myoglobin. explore three mechanistic pathways: nucleophilic, radical, oxocarbenium routes. The nucleophilic most feasible formation enol species that tautomerizes furnish alkylated indole. While this routinely proposed, stereochemical model conspicuously absent until now. show conventionally invoked not responsible for enantiomeric excess. intermediate can stay coordinated catalyst different binding sites placing in proximity chiral environment affecting stereoselective proton transfer. Both strength are crucial high selectivity. Our provides much needed insights modest–low selectivities systems could help expediting discovery efficient catalytic system. These underpinnings also be applicable other metal (Rh, Pd, Cu, etc.)-catalyzed X–H insertion reactions.

Language: Английский

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Catalyst Free Chemoselective Carbene Insertion Into COO─H Bond Over ─OH of Salicylic Acid

ChemistrySelect, Journal Year: 2025, Volume and Issue: 10(5)

Published: Jan. 31, 2025

Abstract The α‐ salicylate esters are found in natural products and play a vital role biological processes. Understanding their structures functions can provide insights into biochemical pathways potential therapeutic targets. Herein, we have developed strategy without the use of metal catalysts or additives for chemoselective carbene insertion COO─H bond over ─OH salicylic acid. Salicylic acids were reacted with diazo compounds to yield α‐salicylate at 150 °C. Having realized importance esters, generalized our various as well thiosalicylic acids. All reactions produced expected good excellent yields. It has been observed that acid manner while mixture products. plausible mechanism reaction supported by DFT calculations origin chemoselectivity help local Fukui functions. synthesized isolated characterized sophisticated analytical spectroscopic techniques including single crystal X‐ray analysis.

Language: Английский

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Metal-Associated Enols as Key Intermediates in Controlling Enantioselectivity in Carbene Insertion Reactions

Synlett, Journal Year: 2025, Volume and Issue: unknown

Published: March 11, 2025

Abstract Transition-metal-catalysed asymmetric carbene insertion reactions into various X–H bonds typically suffer from poor stereoselectivity. It has been proposed that the presence of metal-free intermediates leads to erosion selectivity. In current account, we discuss our recent efforts understand mechanism and stereochemical model Rh- Fe-catalysed indole phenol. Our detailed DFT calculations show all transformations adopt a common involving an enol intermediate, further tautomerisation which is key stereodetermining step. To account for enantioinduction, propose novel metal-associated species can be solving challenges in reactions. The geometry metal–enol complex interaction between chiral metal prochiral play important roles driving reaction toward particular stereoisomer. 1 Introduction 2 Rh-Catalysed Carbene Insertion Indole 3 Fe-Catalysed C–H Functionalisation 4 O–H 5 Conclusion

Language: Английский

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